python/mozbuild/mozbuild/frontend/emitter.py
author Nathan Froyd <froydnj@gmail.com>
Mon, 09 Jul 2018 18:35:49 -0400
changeset 425538 eb28d28e00717947f59a5db318563fffff80885f
parent 425537 e96225163a763f78c0b7857bfdbb3b999e3ef97b
child 426649 b30d58d58f69812c16751870a2c19c8652b7604b
permissions -rw-r--r--
Bug 1444171 - Add pgo-generate-only source functionality; r=glandium For clang-cl, we want to add code to libxul that only exists during the PGO generation phase, so we can collect data. The most expedient way to do that is to enable certain files in SOURCES to be marked as to only be compiled during the PGO generation step.

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

from __future__ import absolute_import, unicode_literals

import itertools
import logging
import os
import traceback
import sys
import time

from collections import defaultdict, OrderedDict
from mach.mixin.logging import LoggingMixin
from mozbuild.util import (
    memoize,
    OrderedDefaultDict,
)

import mozpack.path as mozpath
import mozinfo
import pytoml

from .data import (
    BaseRustProgram,
    BaseSources,
    ChromeManifestEntry,
    ComputedFlags,
    ConfigFileSubstitution,
    Defines,
    DirectoryTraversal,
    Exports,
    FinalTargetFiles,
    FinalTargetPreprocessedFiles,
    GeneratedFile,
    GeneratedSources,
    GnProjectData,
    ExternalStaticLibrary,
    ExternalSharedLibrary,
    HostDefines,
    HostGeneratedSources,
    HostLibrary,
    HostProgram,
    HostRustProgram,
    HostSharedLibrary,
    HostSimpleProgram,
    HostSources,
    InstallationTarget,
    IPDLCollection,
    JARManifest,
    Library,
    Linkable,
    LocalInclude,
    LocalizedFiles,
    LocalizedPreprocessedFiles,
    ObjdirFiles,
    ObjdirPreprocessedFiles,
    PerSourceFlag,
    PgoGenerateOnlySources,
    WebIDLCollection,
    Program,
    RustLibrary,
    HostRustLibrary,
    RustProgram,
    RustTests,
    SharedLibrary,
    SimpleProgram,
    Sources,
    StaticLibrary,
    TestHarnessFiles,
    TestManifest,
    UnifiedSources,
    VariablePassthru,
    XPIDLFile,
)
from mozpack.chrome.manifest import (
    Manifest,
)

from .reader import SandboxValidationError

from ..testing import (
    TEST_MANIFESTS,
    REFTEST_FLAVORS,
    WEB_PLATFORM_TESTS_FLAVORS,
    SupportFilesConverter,
)

from .context import (
    Context,
    SourcePath,
    ObjDirPath,
    Path,
    SubContext,
    TemplateContext,
)

from mozbuild.base import ExecutionSummary


class TreeMetadataEmitter(LoggingMixin):
    """Converts the executed mozbuild files into data structures.

    This is a bridge between reader.py and data.py. It takes what was read by
    reader.BuildReader and converts it into the classes defined in the data
    module.
    """

    def __init__(self, config):
        self.populate_logger()

        self.config = config

        mozinfo.find_and_update_from_json(config.topobjdir)

        # Python 2.6 doesn't allow unicode keys to be used for keyword
        # arguments. This gross hack works around the problem until we
        # rid ourselves of 2.6.
        self.info = {}
        for k, v in mozinfo.info.items():
            if isinstance(k, unicode):
                k = k.encode('ascii')
            self.info[k] = v

        self._libs = OrderedDefaultDict(list)
        self._binaries = OrderedDict()
        self._compile_dirs = set()
        self._host_compile_dirs = set()
        self._rust_compile_dirs = set()
        self._asm_compile_dirs = set()
        self._compile_flags = dict()
        self._compile_as_flags = dict()
        self._linkage = []
        self._static_linking_shared = set()
        self._crate_verified_local = set()
        self._crate_directories = dict()
        self._idls = defaultdict(set)

        # Keep track of external paths (third party build systems), starting
        # from what we run a subconfigure in. We'll eliminate some directories
        # as we traverse them with moz.build (e.g. js/src).
        subconfigures = os.path.join(self.config.topobjdir, 'subconfigures')
        paths = []
        if os.path.exists(subconfigures):
            paths = open(subconfigures).read().splitlines()
        self._external_paths = set(mozpath.normsep(d) for d in paths)

        self._emitter_time = 0.0
        self._object_count = 0
        self._test_files_converter = SupportFilesConverter()

    def summary(self):
        return ExecutionSummary(
            'Processed into {object_count:d} build config descriptors in '
            '{execution_time:.2f}s',
            execution_time=self._emitter_time,
            object_count=self._object_count)

    def emit(self, output, emitfn=None):
        """Convert the BuildReader output into data structures.

        The return value from BuildReader.read_topsrcdir() (a generator) is
        typically fed into this function.
        """
        contexts = {}
        emitfn = emitfn or self.emit_from_context

        def emit_objs(objs):
            for o in objs:
                self._object_count += 1
                yield o

        for out in output:
            # Nothing in sub-contexts is currently of interest to us. Filter
            # them all out.
            if isinstance(out, SubContext):
                continue

            if isinstance(out, Context):
                # Keep all contexts around, we will need them later.
                contexts[out.objdir] = out

                start = time.time()
                # We need to expand the generator for the timings to work.
                objs = list(emitfn(out))
                self._emitter_time += time.time() - start

                for o in emit_objs(objs): yield o

            else:
                raise Exception('Unhandled output type: %s' % type(out))

        # Don't emit Linkable objects when COMPILE_ENVIRONMENT is not set
        if self.config.substs.get('COMPILE_ENVIRONMENT'):
            start = time.time()
            objs = list(self._emit_libs_derived(contexts))
            self._emitter_time += time.time() - start

            for o in emit_objs(objs): yield o

    def _emit_libs_derived(self, contexts):

        # First aggregate idl sources.
        webidl_attrs = [
            ('GENERATED_EVENTS_WEBIDL_FILES', lambda c: c.generated_events_sources),
            ('GENERATED_WEBIDL_FILES', lambda c: c.generated_sources),
            ('PREPROCESSED_TEST_WEBIDL_FILES', lambda c: c.preprocessed_test_sources),
            ('PREPROCESSED_WEBIDL_FILES', lambda c: c.preprocessed_sources),
            ('TEST_WEBIDL_FILES', lambda c: c.test_sources),
            ('WEBIDL_FILES', lambda c: c.sources),
            ('WEBIDL_EXAMPLE_INTERFACES', lambda c: c.example_interfaces),
        ]
        ipdl_attrs = [
            ('IPDL_SOURCES', lambda c: c.sources),
            ('PREPROCESSED_IPDL_SOURCES', lambda c: c.preprocessed_sources),
        ]

        idl_sources = {}
        for root, cls, attrs in ((self.config.substs.get('WEBIDL_ROOT'),
                                  WebIDLCollection, webidl_attrs),
                                 (self.config.substs.get('IPDL_ROOT'),
                                  IPDLCollection, ipdl_attrs)):
            if root:
                collection = cls(contexts[root])
                for var, src_getter in attrs:
                    src_getter(collection).update(self._idls[var])

                idl_sources[root] = collection.all_source_files()
                if isinstance(collection, WebIDLCollection):
                    # Test webidl sources are added here as a somewhat special
                    # case.
                    idl_sources[mozpath.join(root, 'test')] = [s for s in collection.all_test_cpp_basenames()]

                yield collection


        # Next do FINAL_LIBRARY linkage.
        for lib in (l for libs in self._libs.values() for l in libs):
            if not isinstance(lib, (StaticLibrary, RustLibrary)) or not lib.link_into:
                continue
            if lib.link_into not in self._libs:
                raise SandboxValidationError(
                    'FINAL_LIBRARY ("%s") does not match any LIBRARY_NAME'
                    % lib.link_into, contexts[lib.objdir])
            candidates = self._libs[lib.link_into]

            # When there are multiple candidates, but all are in the same
            # directory and have a different type, we want all of them to
            # have the library linked. The typical usecase is when building
            # both a static and a shared library in a directory, and having
            # that as a FINAL_LIBRARY.
            if len(set(type(l) for l in candidates)) == len(candidates) and \
                   len(set(l.objdir for l in candidates)) == 1:
                for c in candidates:
                    c.link_library(lib)
            else:
                raise SandboxValidationError(
                    'FINAL_LIBRARY ("%s") matches a LIBRARY_NAME defined in '
                    'multiple places:\n    %s' % (lib.link_into,
                    '\n    '.join(l.objdir for l in candidates)),
                    contexts[lib.objdir])

        # ...and USE_LIBS linkage.
        for context, obj, variable in self._linkage:
            self._link_libraries(context, obj, variable, idl_sources)

        def recurse_refs(lib):
            for o in lib.refs:
                yield o
                if isinstance(o, StaticLibrary):
                    for q in recurse_refs(o):
                        yield q

        # Check that all static libraries refering shared libraries in
        # USE_LIBS are linked into a shared library or program.
        for lib in self._static_linking_shared:
            if all(isinstance(o, StaticLibrary) for o in recurse_refs(lib)):
                shared_libs = sorted(l.basename for l in lib.linked_libraries
                    if isinstance(l, SharedLibrary))
                raise SandboxValidationError(
                    'The static "%s" library is not used in a shared library '
                    'or a program, but USE_LIBS contains the following shared '
                    'library names:\n    %s\n\nMaybe you can remove the '
                    'static "%s" library?' % (lib.basename,
                    '\n    '.join(shared_libs), lib.basename),
                    contexts[lib.objdir])

        # Propagate LIBRARY_DEFINES to all child libraries recursively.
        def propagate_defines(outerlib, defines):
            outerlib.lib_defines.update(defines)
            for lib in outerlib.linked_libraries:
                # Propagate defines only along FINAL_LIBRARY paths, not USE_LIBS
                # paths.
                if (isinstance(lib, StaticLibrary) and
                        lib.link_into == outerlib.basename):
                    propagate_defines(lib, defines)

        for lib in (l for libs in self._libs.values() for l in libs):
            if isinstance(lib, Library):
                propagate_defines(lib, lib.lib_defines)
            yield lib


        for lib in (l for libs in self._libs.values() for l in libs):
            lib_defines = list(lib.lib_defines.get_defines())
            if lib_defines:
                objdir_flags = self._compile_flags[lib.objdir]
                objdir_flags.resolve_flags('LIBRARY_DEFINES', lib_defines)

                objdir_flags = self._compile_as_flags.get(lib.objdir)
                if objdir_flags:
                    objdir_flags.resolve_flags('LIBRARY_DEFINES', lib_defines)

        for flags_obj in self._compile_flags.values():
            yield flags_obj

        for flags_obj in self._compile_as_flags.values():
            yield flags_obj

        for obj in self._binaries.values():
            yield obj


    LIBRARY_NAME_VAR = {
        'host': 'HOST_LIBRARY_NAME',
        'target': 'LIBRARY_NAME',
    }

    LIBSTDCXX_VAR = {
        'host': 'MOZ_LIBSTDCXX_HOST_VERSION',
        'target': 'MOZ_LIBSTDCXX_TARGET_VERSION',
    }

    STDCXXCOMPAT_NAME = {
        'host': 'host_stdc++compat',
        'target': 'stdc++compat',
    }

    def _link_libraries(self, context, obj, variable, extra_sources):
        """Add linkage declarations to a given object."""
        assert isinstance(obj, Linkable)

        if context.objdir in extra_sources:
            # All "extra sources" are .cpp for the moment, and happen to come
            # first in order.
            obj.sources['.cpp'] = extra_sources[context.objdir] + obj.sources['.cpp']

        for path in context.get(variable, []):
            self._link_library(context, obj, variable, path)

        # Link system libraries from OS_LIBS/HOST_OS_LIBS.
        for lib in context.get(variable.replace('USE', 'OS'), []):
            obj.link_system_library(lib)

        # We have to wait for all the self._link_library calls above to have
        # happened for obj.cxx_link to be final.
        # FIXME: Theoretically, HostSharedLibrary shouldn't be here (bug
        # 1474022).
        if not isinstance(obj, (StaticLibrary, HostLibrary, HostSharedLibrary,
                                BaseRustProgram)) and obj.cxx_link:
            if context.config.substs.get(self.LIBSTDCXX_VAR[obj.KIND]):
                self._link_library(context, obj, variable,
                                   self.STDCXXCOMPAT_NAME[obj.KIND])
            if obj.KIND == 'target':
                for lib in context.config.substs.get('STLPORT_LIBS', []):
                    obj.link_system_library(lib)

    def _link_library(self, context, obj, variable, path):
        force_static = path.startswith('static:') and obj.KIND == 'target'
        if force_static:
            path = path[7:]
        name = mozpath.basename(path)
        dir = mozpath.dirname(path)
        candidates = [l for l in self._libs[name] if l.KIND == obj.KIND]
        if dir:
            if dir.startswith('/'):
                dir = mozpath.normpath(
                    mozpath.join(obj.topobjdir, dir[1:]))
            else:
                dir = mozpath.normpath(
                    mozpath.join(obj.objdir, dir))
            dir = mozpath.relpath(dir, obj.topobjdir)
            candidates = [l for l in candidates if l.relobjdir == dir]
            if not candidates:
                # If the given directory is under one of the external
                # (third party) paths, use a fake library reference to
                # there.
                for d in self._external_paths:
                    if dir.startswith('%s/' % d):
                        candidates = [self._get_external_library(dir, name,
                            force_static)]
                        break

            if not candidates:
                raise SandboxValidationError(
                    '%s contains "%s", but there is no "%s" %s in %s.'
                    % (variable, path, name,
                    self.LIBRARY_NAME_VAR[obj.KIND], dir), context)

        if len(candidates) > 1:
            # If there's more than one remaining candidate, it could be
            # that there are instances for the same library, in static and
            # shared form.
            libs = {}
            for l in candidates:
                key = mozpath.join(l.relobjdir, l.basename)
                if force_static:
                    if isinstance(l, StaticLibrary):
                        libs[key] = l
                else:
                    if key in libs and isinstance(l, SharedLibrary):
                        libs[key] = l
                    if key not in libs:
                        libs[key] = l
            candidates = libs.values()
            if force_static and not candidates:
                if dir:
                    raise SandboxValidationError(
                        '%s contains "static:%s", but there is no static '
                        '"%s" %s in %s.' % (variable, path, name,
                        self.LIBRARY_NAME_VAR[obj.KIND], dir), context)
                raise SandboxValidationError(
                    '%s contains "static:%s", but there is no static "%s" '
                    '%s in the tree' % (variable, name, name,
                    self.LIBRARY_NAME_VAR[obj.KIND]), context)

        if not candidates:
            raise SandboxValidationError(
                '%s contains "%s", which does not match any %s in the tree.'
                % (variable, path, self.LIBRARY_NAME_VAR[obj.KIND]),
                context)

        elif len(candidates) > 1:
            paths = (mozpath.join(l.relsrcdir, 'moz.build')
                for l in candidates)
            raise SandboxValidationError(
                '%s contains "%s", which matches a %s defined in multiple '
                'places:\n    %s' % (variable, path,
                self.LIBRARY_NAME_VAR[obj.KIND],
                '\n    '.join(paths)), context)

        elif force_static and not isinstance(candidates[0], StaticLibrary):
            raise SandboxValidationError(
                '%s contains "static:%s", but there is only a shared "%s" '
                'in %s. You may want to add FORCE_STATIC_LIB=True in '
                '%s/moz.build, or remove "static:".' % (variable, path,
                name, candidates[0].relobjdir, candidates[0].relobjdir),
                context)

        elif isinstance(obj, StaticLibrary) and isinstance(candidates[0],
                SharedLibrary):
            self._static_linking_shared.add(obj)
        obj.link_library(candidates[0])

    @memoize
    def _get_external_library(self, dir, name, force_static):
        # Create ExternalStaticLibrary or ExternalSharedLibrary object with a
        # context more or less truthful about where the external library is.
        context = Context(config=self.config)
        context.add_source(mozpath.join(self.config.topsrcdir, dir, 'dummy'))
        if force_static:
            return ExternalStaticLibrary(context, name)
        else:
            return ExternalSharedLibrary(context, name)

    def _parse_cargo_file(self, context):
        """Parse the Cargo.toml file in context and return a Python object
        representation of it.  Raise a SandboxValidationError if the Cargo.toml
        file does not exist.  Return a tuple of (config, cargo_file)."""
        cargo_file = mozpath.join(context.srcdir, 'Cargo.toml')
        if not os.path.exists(cargo_file):
            raise SandboxValidationError(
                'No Cargo.toml file found in %s' % cargo_file, context)
        with open(cargo_file, 'r') as f:
            return pytoml.load(f), cargo_file

    def _verify_deps(self, context, crate_dir, crate_name, dependencies, description='Dependency'):
        """Verify that a crate's dependencies all specify local paths."""
        for dep_crate_name, values in dependencies.iteritems():
            # A simple version number.
            if isinstance(values, (str, unicode)):
                raise SandboxValidationError(
                    '%s %s of crate %s does not list a path' % (description, dep_crate_name, crate_name),
                    context)

            dep_path = values.get('path', None)
            if not dep_path:
                raise SandboxValidationError(
                    '%s %s of crate %s does not list a path' % (description, dep_crate_name, crate_name),
                    context)

            # Try to catch the case where somebody listed a
            # local path for development.
            if os.path.isabs(dep_path):
                raise SandboxValidationError(
                    '%s %s of crate %s has a non-relative path' % (description, dep_crate_name, crate_name),
                    context)

            if not os.path.exists(mozpath.join(context.config.topsrcdir, crate_dir, dep_path)):
                raise SandboxValidationError(
                    '%s %s of crate %s refers to a non-existent path' % (description, dep_crate_name, crate_name),
                    context)

    def _rust_library(self, context, libname, static_args, cls=RustLibrary):
        # We need to note any Rust library for linking purposes.
        config, cargo_file = self._parse_cargo_file(context)
        crate_name = config['package']['name']

        if crate_name != libname:
            raise SandboxValidationError(
                'library %s does not match Cargo.toml-defined package %s' % (libname, crate_name),
                context)

        # Check that the [lib.crate-type] field is correct
        lib_section = config.get('lib', None)
        if not lib_section:
            raise SandboxValidationError(
                'Cargo.toml for %s has no [lib] section' % libname,
                context)

        crate_type = lib_section.get('crate-type', None)
        if not crate_type:
            raise SandboxValidationError(
                'Can\'t determine a crate-type for %s from Cargo.toml' % libname,
                context)

        crate_type = crate_type[0]
        if crate_type != 'staticlib':
            raise SandboxValidationError(
                'crate-type %s is not permitted for %s' % (crate_type, libname),
                context)

        cargo_target_dir = context.get('RUST_LIBRARY_TARGET_DIR', '.')

        dependencies = set(config.get('dependencies', {}).iterkeys())

        features = context.get(cls.FEATURES_VAR, [])
        unique_features = set(features)
        if len(features) != len(unique_features):
            raise SandboxValidationError(
                'features for %s should not contain duplicates: %s' % (libname, features),
                context)

        return cls(context, libname, cargo_file, crate_type, dependencies,
                   features, cargo_target_dir, **static_args)


    def _handle_gn_dirs(self, context):
        for target_dir in context.get('GN_DIRS', []):
            context['DIRS'] += [target_dir]
            gn_dir = context['GN_DIRS'][target_dir]
            for v in ('variables',):
                if not getattr(gn_dir, 'variables'):
                    raise SandboxValidationError('Missing value for '
                                                 'GN_DIRS["%s"].%s' % (target_dir, v), context)

            non_unified_sources = set()
            for s in gn_dir.non_unified_sources:
                source = SourcePath(context, s)
                if not os.path.exists(source.full_path):
                    raise SandboxValidationError('Cannot find %s.' % source,
                                                 context)
                non_unified_sources.add(mozpath.join(context.relsrcdir, s))

            yield GnProjectData(context, target_dir, gn_dir, non_unified_sources)


    def _handle_linkables(self, context, passthru, generated_files):
        linkables = []
        host_linkables = []
        def add_program(prog, var):
            if var.startswith('HOST_'):
                host_linkables.append(prog)
            else:
                linkables.append(prog)

        def check_unique_binary(program, kind):
            if program in self._binaries:
                raise SandboxValidationError(
                    'Cannot use "%s" as %s name, '
                    'because it is already used in %s' % (program, kind,
                    self._binaries[program].relsrcdir), context)
        for kind, cls in [('PROGRAM', Program), ('HOST_PROGRAM', HostProgram)]:
            program = context.get(kind)
            if program:
                check_unique_binary(program, kind)
                self._binaries[program] = cls(context, program)
                self._linkage.append((context, self._binaries[program],
                    kind.replace('PROGRAM', 'USE_LIBS')))
                add_program(self._binaries[program], kind)

        all_rust_programs = []
        for kind, cls in [('RUST_PROGRAMS', RustProgram),
                          ('HOST_RUST_PROGRAMS', HostRustProgram)]:
            programs = context[kind]
            if not programs:
                continue

            if kind == 'RUST_PROGRAMS':
                self._rust_compile_dirs.add(context.objdir)
            all_rust_programs.append((programs, kind, cls))

        # Verify Rust program definitions.
        if all_rust_programs:
            config, cargo_file = self._parse_cargo_file(context);
            bin_section = config.get('bin', None)
            if not bin_section:
                raise SandboxValidationError(
                    'Cargo.toml in %s has no [bin] section' % context.srcdir,
                    context)

            defined_binaries = {b['name'] for b in bin_section}

            for programs, kind, cls in all_rust_programs:
                for program in programs:
                    if program not in defined_binaries:
                        raise SandboxValidationError(
                            'Cannot find Cargo.toml definition for %s' % program,
                            context)

                    check_unique_binary(program, kind)
                    self._binaries[program] = cls(context, program, cargo_file)

        for kind, cls in [
                ('SIMPLE_PROGRAMS', SimpleProgram),
                ('CPP_UNIT_TESTS', SimpleProgram),
                ('HOST_SIMPLE_PROGRAMS', HostSimpleProgram)]:
            for program in context[kind]:
                if program in self._binaries:
                    raise SandboxValidationError(
                        'Cannot use "%s" in %s, '
                        'because it is already used in %s' % (program, kind,
                        self._binaries[program].relsrcdir), context)
                self._binaries[program] = cls(context, program,
                    is_unit_test=kind == 'CPP_UNIT_TESTS')
                self._linkage.append((context, self._binaries[program],
                    'HOST_USE_LIBS' if kind == 'HOST_SIMPLE_PROGRAMS'
                    else 'USE_LIBS'))
                add_program(self._binaries[program], kind)

        host_libname = context.get('HOST_LIBRARY_NAME')
        libname = context.get('LIBRARY_NAME')

        if host_libname:
            if host_libname == libname:
                raise SandboxValidationError('LIBRARY_NAME and '
                    'HOST_LIBRARY_NAME must have a different value', context)

            is_rust_library = context.get('IS_RUST_LIBRARY')
            if is_rust_library:
                lib = self._rust_library(context, host_libname, {}, cls=HostRustLibrary)
            elif context.get('FORCE_SHARED_LIB'):
                lib = HostSharedLibrary(context, host_libname)
            else:
                lib = HostLibrary(context, host_libname)
            self._libs[host_libname].append(lib)
            self._linkage.append((context, lib, 'HOST_USE_LIBS'))
            host_linkables.append(lib)

        final_lib = context.get('FINAL_LIBRARY')
        if not libname and final_lib:
            # If no LIBRARY_NAME is given, create one.
            libname = context.relsrcdir.replace('/', '_')

        static_lib = context.get('FORCE_STATIC_LIB')
        shared_lib = context.get('FORCE_SHARED_LIB')

        static_name = context.get('STATIC_LIBRARY_NAME')
        shared_name = context.get('SHARED_LIBRARY_NAME')

        is_framework = context.get('IS_FRAMEWORK')

        soname = context.get('SONAME')

        lib_defines = context.get('LIBRARY_DEFINES')

        shared_args = {}
        static_args = {}

        if final_lib:
            if static_lib:
                raise SandboxValidationError(
                    'FINAL_LIBRARY implies FORCE_STATIC_LIB. '
                    'Please remove the latter.', context)
            if shared_lib:
                raise SandboxValidationError(
                    'FINAL_LIBRARY conflicts with FORCE_SHARED_LIB. '
                    'Please remove one.', context)
            if is_framework:
                raise SandboxValidationError(
                    'FINAL_LIBRARY conflicts with IS_FRAMEWORK. '
                    'Please remove one.', context)
            static_args['link_into'] = final_lib
            static_lib = True

        if libname:
            if is_framework:
                if soname:
                    raise SandboxValidationError(
                        'IS_FRAMEWORK conflicts with SONAME. '
                        'Please remove one.', context)
                shared_lib = True
                shared_args['variant'] = SharedLibrary.FRAMEWORK

            if not static_lib and not shared_lib:
                static_lib = True

            if static_name:
                if not static_lib:
                    raise SandboxValidationError(
                        'STATIC_LIBRARY_NAME requires FORCE_STATIC_LIB',
                        context)
                static_args['real_name'] = static_name

            if shared_name:
                if not shared_lib:
                    raise SandboxValidationError(
                        'SHARED_LIBRARY_NAME requires FORCE_SHARED_LIB',
                        context)
                shared_args['real_name'] = shared_name

            if soname:
                if not shared_lib:
                    raise SandboxValidationError(
                        'SONAME requires FORCE_SHARED_LIB', context)
                shared_args['soname'] = soname

            if context.get('NO_EXPAND_LIBS'):
                if not static_lib:
                    raise SandboxValidationError(
                        'NO_EXPAND_LIBS can only be set for static libraries.',
                        context)
                static_args['no_expand_lib'] = True

            if shared_lib and static_lib:
                if not static_name and not shared_name:
                    raise SandboxValidationError(
                        'Both FORCE_STATIC_LIB and FORCE_SHARED_LIB are True, '
                        'but neither STATIC_LIBRARY_NAME or '
                        'SHARED_LIBRARY_NAME is set. At least one is required.',
                        context)
                if static_name and not shared_name and static_name == libname:
                    raise SandboxValidationError(
                        'Both FORCE_STATIC_LIB and FORCE_SHARED_LIB are True, '
                        'but STATIC_LIBRARY_NAME is the same as LIBRARY_NAME, '
                        'and SHARED_LIBRARY_NAME is unset. Please either '
                        'change STATIC_LIBRARY_NAME or LIBRARY_NAME, or set '
                        'SHARED_LIBRARY_NAME.', context)
                if shared_name and not static_name and shared_name == libname:
                    raise SandboxValidationError(
                        'Both FORCE_STATIC_LIB and FORCE_SHARED_LIB are True, '
                        'but SHARED_LIBRARY_NAME is the same as LIBRARY_NAME, '
                        'and STATIC_LIBRARY_NAME is unset. Please either '
                        'change SHARED_LIBRARY_NAME or LIBRARY_NAME, or set '
                        'STATIC_LIBRARY_NAME.', context)
                if shared_name and static_name and shared_name == static_name:
                    raise SandboxValidationError(
                        'Both FORCE_STATIC_LIB and FORCE_SHARED_LIB are True, '
                        'but SHARED_LIBRARY_NAME is the same as '
                        'STATIC_LIBRARY_NAME. Please change one of them.',
                        context)

            symbols_file = context.get('SYMBOLS_FILE')
            if symbols_file:
                if not shared_lib:
                    raise SandboxValidationError(
                        'SYMBOLS_FILE can only be used with a SHARED_LIBRARY.',
                        context)
                if context.get('DEFFILE'):
                    raise SandboxValidationError(
                        'SYMBOLS_FILE cannot be used along DEFFILE.',
                        context)
                if isinstance(symbols_file, SourcePath):
                    if not os.path.exists(symbols_file.full_path):
                        raise SandboxValidationError(
                            'Path specified in SYMBOLS_FILE does not exist: %s '
                            '(resolved to %s)' % (symbols_file,
                            symbols_file.full_path), context)
                    shared_args['symbols_file'] = True
                else:
                    if symbols_file.target_basename not in generated_files:
                        raise SandboxValidationError(
                            ('Objdir file specified in SYMBOLS_FILE not in ' +
                             'GENERATED_FILES: %s') % (symbols_file,), context)
                    shared_args['symbols_file'] = symbols_file.target_basename

            if shared_lib:
                lib = SharedLibrary(context, libname, **shared_args)
                self._libs[libname].append(lib)
                self._linkage.append((context, lib, 'USE_LIBS'))
                linkables.append(lib)
                if not lib.installed:
                    generated_files.add(lib.lib_name)
                if symbols_file and isinstance(symbols_file, SourcePath):
                    script = mozpath.join(
                        mozpath.dirname(mozpath.dirname(__file__)),
                        'action', 'generate_symbols_file.py')
                    defines = ()
                    if lib.defines:
                        defines = lib.defines.get_defines()
                    yield GeneratedFile(context, script,
                        'generate_symbols_file', lib.symbols_file,
                        [symbols_file], defines)
            if static_lib:
                is_rust_library = context.get('IS_RUST_LIBRARY')
                if is_rust_library:
                    lib = self._rust_library(context, libname, static_args)
                else:
                    lib = StaticLibrary(context, libname, **static_args)
                self._libs[libname].append(lib)
                self._linkage.append((context, lib, 'USE_LIBS'))
                linkables.append(lib)

            if lib_defines:
                if not libname:
                    raise SandboxValidationError('LIBRARY_DEFINES needs a '
                        'LIBRARY_NAME to take effect', context)
                lib.lib_defines.update(lib_defines)

        # Only emit sources if we have linkables defined in the same context.
        # Note the linkables are not emitted in this function, but much later,
        # after aggregation (because of e.g. USE_LIBS processing).
        if not (linkables or host_linkables):
            return

        # Avoid emitting compile flags for directories only containing rust
        # libraries. Emitted compile flags are only relevant to C/C++ sources
        # for the time being, however ldflags must be emitted for the benefit
        # of cargo.
        if not all(isinstance(l, (RustLibrary)) for l in linkables):
            self._compile_dirs.add(context.objdir)
        elif linkables:
            self._rust_compile_dirs.add(context.objdir)

        if host_linkables and not all(isinstance(l, HostRustLibrary) for l in host_linkables):
            self._host_compile_dirs.add(context.objdir)
            # TODO: objdirs with only host things in them shouldn't need target
            # flags, but there's at least one Makefile.in (in
            # build/unix/elfhack) that relies on the value of LDFLAGS being
            # passed to one-off rules.
            self._compile_dirs.add(context.objdir)

        sources = defaultdict(list)
        gen_sources = defaultdict(list)
        pgo_generate_only = set()
        all_flags = {}
        for symbol in ('SOURCES', 'HOST_SOURCES', 'UNIFIED_SOURCES'):
            srcs = sources[symbol]
            gen_srcs = gen_sources[symbol]
            context_srcs = context.get(symbol, [])
            for f in context_srcs:
                full_path = f.full_path
                if isinstance(f, SourcePath):
                    srcs.append(full_path)
                else:
                    assert isinstance(f, Path)
                    gen_srcs.append(full_path)
                if symbol == 'SOURCES':
                    flags = context_srcs[f]
                    if flags:
                        all_flags[full_path] = flags
                    # Files for the generation phase of PGO are unusual, so
                    # it's not unreasonable to require them to be special.
                    if flags.pgo_generate_only:
                        if not isinstance(f, Path):
                            raise SandboxValidationError('pgo_generate_only file'
                                'must not be a generated file: %s' % f, context)
                        if mozpath.splitext(f)[1] != '.cpp':
                            raise SandboxValidationError('pgo_generate_only file'
                                'must be a .cpp file: %s' % f, context)
                        if flags.no_pgo:
                            raise SandboxValidationError('pgo_generate_only files'
                                'cannot be marked no_pgo: %s' % f, context)
                        pgo_generate_only.add(f)

                if isinstance(f, SourcePath) and not os.path.exists(full_path):
                    raise SandboxValidationError('File listed in %s does not '
                        'exist: \'%s\'' % (symbol, full_path), context)

        # UNIFIED_SOURCES only take SourcePaths, so there should be no
        # generated source in here
        assert not gen_sources['UNIFIED_SOURCES']

        no_pgo = context.get('NO_PGO')
        no_pgo_sources = [f for f, flags in all_flags.iteritems()
                          if flags.no_pgo]
        pgo_gen_only_sources = set(f for f, flags in all_flags.iteritems()
                                   if flags.pgo_generate_only)
        if no_pgo:
            if no_pgo_sources:
                raise SandboxValidationError('NO_PGO and SOURCES[...].no_pgo '
                    'cannot be set at the same time', context)
            passthru.variables['NO_PROFILE_GUIDED_OPTIMIZE'] = no_pgo
        if no_pgo_sources:
            passthru.variables['NO_PROFILE_GUIDED_OPTIMIZE'] = no_pgo_sources

        # A map from "canonical suffixes" for a particular source file
        # language to the range of suffixes associated with that language.
        #
        # We deliberately don't list the canonical suffix in the suffix list
        # in the definition; we'll add it in programmatically after defining
        # things.
        suffix_map = {
            '.s': set(['.asm']),
            '.c': set(),
            '.m': set(),
            '.mm': set(),
            '.cpp': set(['.cc', '.cxx']),
            '.S': set(),
        }

        # The inverse of the above, mapping suffixes to their canonical suffix.
        canonicalized_suffix_map = {}
        for suffix, alternatives in suffix_map.iteritems():
            alternatives.add(suffix)
            for a in alternatives:
                canonicalized_suffix_map[a] = suffix

        def canonical_suffix_for_file(f):
            return canonicalized_suffix_map[mozpath.splitext(f)[1]]

        # A map from moz.build variables to the canonical suffixes of file
        # kinds that can be listed therein.
        all_suffixes = list(suffix_map.keys())
        varmap = dict(
            SOURCES=(Sources, GeneratedSources, all_suffixes),
            HOST_SOURCES=(HostSources, HostGeneratedSources, ['.c', '.mm', '.cpp']),
            UNIFIED_SOURCES=(UnifiedSources, None, ['.c', '.mm', '.cpp']),
        )
        # Track whether there are any C++ source files.
        # Technically this won't do the right thing for SIMPLE_PROGRAMS in
        # a directory with mixed C and C++ source, but it's not that important.
        cxx_sources = defaultdict(bool)

        # Source files to track for linkables associated with this context.
        ctxt_sources = defaultdict(lambda: defaultdict(list))

        for variable, (klass, gen_klass, suffixes) in varmap.items():
            allowed_suffixes = set().union(*[suffix_map[s] for s in suffixes])

            # First ensure that we haven't been given filetypes that we don't
            # recognize.
            for f in itertools.chain(sources[variable], gen_sources[variable]):
                ext = mozpath.splitext(f)[1]
                if ext not in allowed_suffixes:
                    raise SandboxValidationError(
                        '%s has an unknown file type.' % f, context)

            for srcs, cls in ((sources[variable], klass),
                              (gen_sources[variable], gen_klass)):
                if variable == 'SOURCES' and pgo_gen_only_sources:
                    srcs = [s for s in srcs if s not in pgo_gen_only_sources]
                # Now sort the files to let groupby work.
                sorted_files = sorted(srcs, key=canonical_suffix_for_file)
                for canonical_suffix, files in itertools.groupby(
                        sorted_files, canonical_suffix_for_file):
                    if canonical_suffix in ('.cpp', '.mm'):
                        cxx_sources[variable] = True
                    elif canonical_suffix in ('.s', '.S'):
                        self._asm_compile_dirs.add(context.objdir)
                    arglist = [context, list(files), canonical_suffix]
                    if variable.startswith('UNIFIED_'):
                        arglist.append(context.get('FILES_PER_UNIFIED_FILE', 16))
                    obj = cls(*arglist)
                    srcs = obj.files
                    if isinstance(obj, UnifiedSources) and obj.have_unified_mapping:
                        srcs = dict(obj.unified_source_mapping).keys()
                    ctxt_sources[variable][canonical_suffix] += sorted(srcs)
                    yield obj

        if ctxt_sources:
            for linkable in linkables:
                for target_var in ('SOURCES', 'UNIFIED_SOURCES'):
                    for suffix, srcs in ctxt_sources[target_var].items():
                        linkable.sources[suffix] += srcs
                if pgo_gen_only_sources:
                    linkable.pgo_gen_only_sources = pgo_gen_only_sources
                if no_pgo_sources:
                    linkable.no_pgo_sources = no_pgo_sources
                elif no_pgo:
                    linkable.no_pgo = True
            for host_linkable in host_linkables:
                for suffix, srcs in ctxt_sources['HOST_SOURCES'].items():
                    host_linkable.sources[suffix] += srcs

        for f, flags in all_flags.iteritems():
            if flags.flags:
                ext = mozpath.splitext(f)[1]
                yield PerSourceFlag(context, f, flags.flags)

        if pgo_generate_only:
            yield PgoGenerateOnlySources(context, pgo_generate_only)

        # If there are any C++ sources, set all the linkables defined here
        # to require the C++ linker.
        for vars, linkable_items in ((('SOURCES', 'UNIFIED_SOURCES'), linkables),
                                     (('HOST_SOURCES',), host_linkables)):
            for var in vars:
                if cxx_sources[var]:
                    for l in linkable_items:
                        l.cxx_link = True
                    break


    def emit_from_context(self, context):
        """Convert a Context to tree metadata objects.

        This is a generator of mozbuild.frontend.data.ContextDerived instances.
        """

        # We only want to emit an InstallationTarget if one of the consulted
        # variables is defined. Later on, we look up FINAL_TARGET, which has
        # the side-effect of populating it. So, we need to do this lookup
        # early.
        if any(k in context for k in ('FINAL_TARGET', 'XPI_NAME', 'DIST_SUBDIR')):
            yield InstallationTarget(context)

        for obj in self._handle_gn_dirs(context):
            yield obj

        # We always emit a directory traversal descriptor. This is needed by
        # the recursive make backend.
        for o in self._emit_directory_traversal_from_context(context): yield o

        for obj in self._process_xpidl(context):
            yield obj

        computed_flags = ComputedFlags(context, context['COMPILE_FLAGS'])
        computed_link_flags = ComputedFlags(context, context['LINK_FLAGS'])
        computed_host_flags = ComputedFlags(context, context['HOST_COMPILE_FLAGS'])
        computed_as_flags = ComputedFlags(context, context['ASM_FLAGS'])

        # Proxy some variables as-is until we have richer classes to represent
        # them. We should aim to keep this set small because it violates the
        # desired abstraction of the build definition away from makefiles.
        passthru = VariablePassthru(context)
        varlist = [
            'EXTRA_DSO_LDOPTS',
            'RCFILE',
            'RESFILE',
            'RCINCLUDE',
            'DEFFILE',
            'WIN32_EXE_LDFLAGS',
            'USE_EXTENSION_MANIFEST',
            'NO_JS_MANIFEST',
            'HAS_MISC_RULE',
        ]
        for v in varlist:
            if v in context and context[v]:
                passthru.variables[v] = context[v]

        if context.config.substs.get('OS_TARGET') == 'WINNT' and \
                context['DELAYLOAD_DLLS']:
            context['LDFLAGS'].extend([('-DELAYLOAD:%s' % dll)
                for dll in context['DELAYLOAD_DLLS']])
            context['OS_LIBS'].append('delayimp')

        for v in ['CMFLAGS', 'CMMFLAGS']:
            if v in context and context[v]:
                passthru.variables['MOZBUILD_' + v] = context[v]

        for v in ['CXXFLAGS', 'CFLAGS']:
            if v in context and context[v]:
                computed_flags.resolve_flags('MOZBUILD_%s' % v, context[v])

        for v in ['HOST_CXXFLAGS', 'HOST_CFLAGS']:
            if v in context and context[v]:
                computed_host_flags.resolve_flags('MOZBUILD_%s' % v, context[v])

        if 'LDFLAGS' in context and context['LDFLAGS']:
            computed_link_flags.resolve_flags('MOZBUILD', context['LDFLAGS'])

        deffile = context['DEFFILE']
        if deffile and context.config.substs.get('OS_ARCH') == 'WINNT':
            if context.config.substs.get('GNU_CC'):
                computed_link_flags.resolve_flags('DEFFILE', [deffile])
            else:
                computed_link_flags.resolve_flags('DEFFILE',
                                                  ['-DEF:' + deffile])

        dist_install = context['DIST_INSTALL']
        if dist_install is True:
            passthru.variables['DIST_INSTALL'] = True
        elif dist_install is False:
            passthru.variables['NO_DIST_INSTALL'] = True

        # Ideally, this should be done in templates, but this is difficult at
        # the moment because USE_STATIC_LIBS can be set after a template
        # returns. Eventually, with context-based templates, it will be
        # possible.
        if (context.config.substs.get('OS_ARCH') == 'WINNT' and
                not context.config.substs.get('GNU_CC')):
            use_static_lib = (context.get('USE_STATIC_LIBS') and
                              not context.config.substs.get('MOZ_ASAN'))
            rtl_flag = '-MT' if use_static_lib else '-MD'
            if (context.config.substs.get('MOZ_DEBUG') and
                    not context.config.substs.get('MOZ_NO_DEBUG_RTL')):
                rtl_flag += 'd'
            computed_flags.resolve_flags('RTL', [rtl_flag])
            # For PGO clang-cl builds, we generate order files in the
            # profile generate phase that are subsequently used to link the
            # final library.  We need to provide flags to the compiler to
            # have it instrument functions for generating the data for the
            # order file.  We'd normally put flags like these in
            # PROFILE_GEN_CFLAGS or the like, but we need to only use the
            # flags in contexts where we're compiling code for xul.
            code_for_xul = context.get('FINAL_LIBRARY', 'notxul') == 'xul'
            if context.config.substs.get('CLANG_CL') and code_for_xul:
                computed_flags.resolve_flags('PROFILE_GEN_DYN_CFLAGS',
                                             ['-Xclang',
                                              '-finstrument-functions-after-inlining'])
            if not context.config.substs.get('CROSS_COMPILE'):
                computed_host_flags.resolve_flags('RTL', [rtl_flag])

        generated_files = set()
        localized_generated_files = set()
        for obj in self._process_generated_files(context):
            for f in obj.outputs:
                generated_files.add(f)
                if obj.localized:
                    localized_generated_files.add(f)
            yield obj

        for path in context['CONFIGURE_SUBST_FILES']:
            sub = self._create_substitution(ConfigFileSubstitution, context,
                path)
            generated_files.add(str(sub.relpath))
            yield sub

        for defines_var, cls, backend_flags in (('DEFINES', Defines, (computed_flags, computed_as_flags)),
                                                ('HOST_DEFINES', HostDefines, (computed_host_flags,))):
            defines = context.get(defines_var)
            if defines:
                defines_obj = cls(context, defines)
                if isinstance(defines_obj, Defines):
                    # DEFINES have consumers outside the compile command line,
                    # HOST_DEFINES do not.
                    yield defines_obj
            else:
                # If we don't have explicitly set defines we need to make sure
                # initialized values if present end up in computed flags.
                defines_obj = cls(context, context[defines_var])

            defines_from_obj = list(defines_obj.get_defines())
            if defines_from_obj:
                for flags in backend_flags:
                    flags.resolve_flags(defines_var, defines_from_obj)

        idl_vars = (
            'GENERATED_EVENTS_WEBIDL_FILES',
            'GENERATED_WEBIDL_FILES',
            'PREPROCESSED_TEST_WEBIDL_FILES',
            'PREPROCESSED_WEBIDL_FILES',
            'TEST_WEBIDL_FILES',
            'WEBIDL_FILES',
            'IPDL_SOURCES',
            'PREPROCESSED_IPDL_SOURCES',
        )
        for context_var in idl_vars:
            for name in context.get(context_var, []):
                self._idls[context_var].add(mozpath.join(context.srcdir, name))
        # WEBIDL_EXAMPLE_INTERFACES do not correspond to files.
        for name in context.get('WEBIDL_EXAMPLE_INTERFACES', []):
            self._idls['WEBIDL_EXAMPLE_INTERFACES'].add(name)

        local_includes = []
        for local_include in context.get('LOCAL_INCLUDES', []):
            full_path = local_include.full_path
            if (not isinstance(local_include, ObjDirPath) and
                    not os.path.exists(full_path)):
                raise SandboxValidationError('Path specified in LOCAL_INCLUDES '
                    'does not exist: %s (resolved to %s)' % (local_include,
                    full_path), context)
            if (full_path == context.config.topsrcdir or
                    full_path == context.config.topobjdir):
                raise SandboxValidationError('Path specified in LOCAL_INCLUDES '
                    '(%s) resolves to the topsrcdir or topobjdir (%s), which is '
                    'not allowed' % (local_include, full_path), context)
            include_obj = LocalInclude(context, local_include)
            local_includes.append(include_obj.path.full_path)
            yield include_obj

        computed_flags.resolve_flags('LOCAL_INCLUDES', ['-I%s' % p for p in local_includes])
        computed_as_flags.resolve_flags('LOCAL_INCLUDES', ['-I%s' % p for p in local_includes])
        computed_host_flags.resolve_flags('LOCAL_INCLUDES', ['-I%s' % p for p in local_includes])

        for obj in self._handle_linkables(context, passthru, generated_files):
            yield obj

        generated_files.update(['%s%s' % (k, self.config.substs.get('BIN_SUFFIX', '')) for k in self._binaries.keys()])

        components = []
        for var, cls in (
            ('EXPORTS', Exports),
            ('FINAL_TARGET_FILES', FinalTargetFiles),
            ('FINAL_TARGET_PP_FILES', FinalTargetPreprocessedFiles),
            ('LOCALIZED_FILES', LocalizedFiles),
            ('LOCALIZED_PP_FILES', LocalizedPreprocessedFiles),
            ('OBJDIR_FILES', ObjdirFiles),
            ('OBJDIR_PP_FILES', ObjdirPreprocessedFiles),
            ('TEST_HARNESS_FILES', TestHarnessFiles),
        ):
            all_files = context.get(var)
            if not all_files:
                continue
            if dist_install is False and var != 'TEST_HARNESS_FILES':
                raise SandboxValidationError(
                    '%s cannot be used with DIST_INSTALL = False' % var,
                    context)
            has_prefs = False
            has_resources = False
            for base, files in all_files.walk():
                if var == 'TEST_HARNESS_FILES' and not base:
                    raise SandboxValidationError(
                        'Cannot install files to the root of TEST_HARNESS_FILES', context)
                if base == 'components':
                    components.extend(files)
                if base == 'defaults/pref':
                    has_prefs = True
                if mozpath.split(base)[0] == 'res':
                    has_resources = True
                for f in files:
                    if (var in ('FINAL_TARGET_PP_FILES',
                                'OBJDIR_PP_FILES',
                                'LOCALIZED_PP_FILES') and
                        not isinstance(f, SourcePath)):
                        raise SandboxValidationError(
                                ('Only source directory paths allowed in ' +
                                 '%s: %s')
                                % (var, f,), context)
                    if var.startswith('LOCALIZED_'):
                        if isinstance(f, SourcePath):
                            if f.startswith('en-US/'):
                                pass
                            elif 'locales/en-US/' in f:
                                pass
                            else:
                                raise SandboxValidationError(
                                        '%s paths must start with `en-US/` or '
                                        'contain `locales/en-US/`: %s'
                                        % (var, f,), context)

                    if not isinstance(f, ObjDirPath):
                        path = f.full_path
                        if '*' not in path and not os.path.exists(path):
                            raise SandboxValidationError(
                                'File listed in %s does not exist: %s'
                                % (var, path), context)
                    else:
                        # TODO: Bug 1254682 - The '/' check is to allow
                        # installing files generated from other directories,
                        # which is done occasionally for tests. However, it
                        # means we don't fail early if the file isn't actually
                        # created by the other moz.build file.
                        if f.target_basename not in generated_files and '/' not in f:
                            raise SandboxValidationError(
                                ('Objdir file listed in %s not in ' +
                                 'GENERATED_FILES: %s') % (var, f), context)

                        if var.startswith('LOCALIZED_'):
                            # Further require that LOCALIZED_FILES are from
                            # LOCALIZED_GENERATED_FILES.
                            if f.target_basename not in localized_generated_files:
                                raise SandboxValidationError(
                                    ('Objdir file listed in %s not in ' +
                                     'LOCALIZED_GENERATED_FILES: %s') % (var, f), context)
                        else:
                            # Additionally, don't allow LOCALIZED_GENERATED_FILES to be used
                            # in anything *but* LOCALIZED_FILES.
                            if f.target_basename in localized_generated_files:
                                raise SandboxValidationError(
                                    ('Outputs of LOCALIZED_GENERATED_FILES cannot be used in %s: ' +
                                     '%s') % (var, f), context)

            # Addons (when XPI_NAME is defined) and Applications (when
            # DIST_SUBDIR is defined) use a different preferences directory
            # (default/preferences) from the one the GRE uses (defaults/pref).
            # Hence, we move the files from the latter to the former in that
            # case.
            if has_prefs and (context.get('XPI_NAME') or
                              context.get('DIST_SUBDIR')):
                all_files.defaults.preferences += all_files.defaults.pref
                del all_files.defaults._children['pref']

            if has_resources and (context.get('DIST_SUBDIR') or
                                  context.get('XPI_NAME')):
                raise SandboxValidationError(
                    'RESOURCES_FILES cannot be used with DIST_SUBDIR or '
                    'XPI_NAME.', context)

            yield cls(context, all_files)

        # Check for manifest declarations in EXTRA_{PP_,}COMPONENTS.
        if any(e.endswith('.js') for e in components) and \
                not any(e.endswith('.manifest') for e in components) and \
                not context.get('NO_JS_MANIFEST', False):
            raise SandboxValidationError('A .js component was specified in EXTRA_COMPONENTS '
                                         'or EXTRA_PP_COMPONENTS without a matching '
                                         '.manifest file.  See '
                                         'https://developer.mozilla.org/en/XPCOM/XPCOM_changes_in_Gecko_2.0 .',
                                         context);

        for c in components:
            if c.endswith('.manifest'):
                yield ChromeManifestEntry(context, 'chrome.manifest',
                                          Manifest('components',
                                                   mozpath.basename(c)))

        if self.config.substs.get('MOZ_RUST_TESTS', None):
            rust_tests = context.get('RUST_TESTS', [])
            if rust_tests:
                # TODO: more sophisticated checking of the declared name vs.
                # contents of the Cargo.toml file.
                features = context.get('RUST_TEST_FEATURES', [])

                yield RustTests(context, rust_tests, features)

        for obj in self._process_test_manifests(context):
            yield obj

        for obj in self._process_jar_manifests(context):
            yield obj

        computed_as_flags.resolve_flags('MOZBUILD',
                                        context.get('ASFLAGS'))

        if context.get('USE_YASM') is True:
            yasm = context.config.substs.get('YASM')
            if not yasm:
                raise SandboxValidationError('yasm is not available', context)
            passthru.variables['AS'] = yasm
            passthru.variables['AS_DASH_C_FLAG'] = ''
            computed_as_flags.resolve_flags('OS',
                                            context.config.substs.get('YASM_ASFLAGS', []))


        if passthru.variables:
            yield passthru

        if context.objdir in self._compile_dirs:
            self._compile_flags[context.objdir] = computed_flags
            yield computed_link_flags
        elif context.objdir in self._rust_compile_dirs:
            yield computed_link_flags

        if context.objdir in self._asm_compile_dirs:
            self._compile_as_flags[context.objdir] = computed_as_flags

        if context.objdir in self._host_compile_dirs:
            yield computed_host_flags


    def _create_substitution(self, cls, context, path):
        sub = cls(context)
        sub.input_path = '%s.in' % path.full_path
        sub.output_path = path.translated
        sub.relpath = path

        return sub

    def _process_xpidl(self, context):
        # XPIDL source files get processed and turned into .h and .xpt files.
        # If there are multiple XPIDL files in a directory, they get linked
        # together into a final .xpt, which has the name defined by
        # XPIDL_MODULE.
        xpidl_module = context['XPIDL_MODULE']

        if context['XPIDL_SOURCES'] and not xpidl_module:
            raise SandboxValidationError('XPIDL_MODULE must be defined if '
                'XPIDL_SOURCES is defined.', context)

        if xpidl_module and not context['XPIDL_SOURCES']:
            raise SandboxValidationError('XPIDL_MODULE cannot be defined '
                'unless there are XPIDL_SOURCES', context)

        if context['XPIDL_SOURCES'] and context['DIST_INSTALL'] is False:
            self.log(logging.WARN, 'mozbuild_warning', dict(
                path=context.main_path),
                '{path}: DIST_INSTALL = False has no effect on XPIDL_SOURCES.')

        for idl in context['XPIDL_SOURCES']:
            yield XPIDLFile(context, mozpath.join(context.srcdir, idl),
                xpidl_module)

    def _process_generated_files(self, context):
        for path in context['CONFIGURE_DEFINE_FILES']:
            script = mozpath.join(mozpath.dirname(mozpath.dirname(__file__)),
                                  'action', 'process_define_files.py')
            yield GeneratedFile(context, script, 'process_define_file',
                                unicode(path),
                                [Path(context, path + '.in')])

        generated_files = context.get('GENERATED_FILES') or []
        localized_generated_files = context.get('LOCALIZED_GENERATED_FILES') or []
        if not (generated_files or localized_generated_files):
            return

        for (localized, gen) in ((False, generated_files), (True, localized_generated_files)):
            for f in gen:
                flags = gen[f]
                outputs = f
                inputs = []
                if flags.script:
                    method = "main"
                    script = SourcePath(context, flags.script).full_path

                    # Deal with cases like "C:\\path\\to\\script.py:function".
                    if '.py:' in script:
                        script, method = script.rsplit('.py:', 1)
                        script += '.py'

                    if not os.path.exists(script):
                        raise SandboxValidationError(
                            'Script for generating %s does not exist: %s'
                            % (f, script), context)
                    if os.path.splitext(script)[1] != '.py':
                        raise SandboxValidationError(
                            'Script for generating %s does not end in .py: %s'
                            % (f, script), context)
                else:
                    script = None
                    method = None

                for i in flags.inputs:
                    p = Path(context, i)
                    if (isinstance(p, SourcePath) and
                            not os.path.exists(p.full_path)):
                        raise SandboxValidationError(
                            'Input for generating %s does not exist: %s'
                            % (f, p.full_path), context)
                    inputs.append(p)

                yield GeneratedFile(context, script, method, outputs, inputs,
                                    flags.flags, localized=localized, force=flags.force)

    def _process_test_manifests(self, context):
        for prefix, info in TEST_MANIFESTS.items():
            for path, manifest in context.get('%s_MANIFESTS' % prefix, []):
                for obj in self._process_test_manifest(context, info, path, manifest):
                    yield obj

        for flavor in REFTEST_FLAVORS:
            for path, manifest in context.get('%s_MANIFESTS' % flavor.upper(), []):
                for obj in self._process_reftest_manifest(context, flavor, path, manifest):
                    yield obj

        for flavor in WEB_PLATFORM_TESTS_FLAVORS:
            for path, manifest in context.get("%s_MANIFESTS" % flavor.upper().replace('-', '_'), []):
                for obj in self._process_web_platform_tests_manifest(context, path, manifest):
                    yield obj

    def _process_test_manifest(self, context, info, manifest_path, mpmanifest):
        flavor, install_root, install_subdir, package_tests = info

        path = manifest_path.full_path
        manifest_dir = mozpath.dirname(path)
        manifest_reldir = mozpath.dirname(mozpath.relpath(path,
            context.config.topsrcdir))
        manifest_sources = [mozpath.relpath(pth, context.config.topsrcdir)
                            for pth in mpmanifest.source_files]
        install_prefix = mozpath.join(install_root, install_subdir)

        try:
            if not mpmanifest.tests:
                raise SandboxValidationError('Empty test manifest: %s'
                    % path, context)

            defaults = mpmanifest.manifest_defaults[os.path.normpath(path)]
            obj = TestManifest(context, path, mpmanifest, flavor=flavor,
                install_prefix=install_prefix,
                relpath=mozpath.join(manifest_reldir, mozpath.basename(path)),
                sources=manifest_sources,
                dupe_manifest='dupe-manifest' in defaults)

            filtered = mpmanifest.tests

            missing = [t['name'] for t in filtered if not os.path.exists(t['path'])]
            if missing:
                raise SandboxValidationError('Test manifest (%s) lists '
                    'test that does not exist: %s' % (
                    path, ', '.join(missing)), context)

            out_dir = mozpath.join(install_prefix, manifest_reldir)
            if 'install-to-subdir' in defaults:
                # This is terrible, but what are you going to do?
                out_dir = mozpath.join(out_dir, defaults['install-to-subdir'])
                obj.manifest_obj_relpath = mozpath.join(manifest_reldir,
                                                        defaults['install-to-subdir'],
                                                        mozpath.basename(path))

            def process_support_files(test):
                install_info = self._test_files_converter.convert_support_files(
                    test, install_root, manifest_dir, out_dir)

                obj.pattern_installs.extend(install_info.pattern_installs)
                for source, dest in install_info.installs:
                    obj.installs[source] = (dest, False)
                obj.external_installs |= install_info.external_installs
                for install_path in install_info.deferred_installs:
                    if all(['*' not in install_path,
                            not os.path.isfile(mozpath.join(context.config.topsrcdir,
                                                            install_path[2:])),
                            install_path not in install_info.external_installs]):
                        raise SandboxValidationError('Error processing test '
                           'manifest %s: entry in support-files not present '
                           'in the srcdir: %s' % (path, install_path), context)

                obj.deferred_installs |= install_info.deferred_installs

            for test in filtered:
                obj.tests.append(test)

                # Some test files are compiled and should not be copied into the
                # test package. They function as identifiers rather than files.
                if package_tests:
                    manifest_relpath = mozpath.relpath(test['path'],
                        mozpath.dirname(test['manifest']))
                    obj.installs[mozpath.normpath(test['path'])] = \
                        ((mozpath.join(out_dir, manifest_relpath)), True)

                process_support_files(test)

            for path, m_defaults in mpmanifest.manifest_defaults.items():
                process_support_files(m_defaults)

            # We also copy manifests into the output directory,
            # including manifests from [include:foo] directives.
            for mpath in mpmanifest.manifests():
                mpath = mozpath.normpath(mpath)
                out_path = mozpath.join(out_dir, mozpath.basename(mpath))
                obj.installs[mpath] = (out_path, False)

            # Some manifests reference files that are auto generated as
            # part of the build or shouldn't be installed for some
            # reason. Here, we prune those files from the install set.
            # FUTURE we should be able to detect autogenerated files from
            # other build metadata. Once we do that, we can get rid of this.
            for f in defaults.get('generated-files', '').split():
                # We re-raise otherwise the stack trace isn't informative.
                try:
                    del obj.installs[mozpath.join(manifest_dir, f)]
                except KeyError:
                    raise SandboxValidationError('Error processing test '
                        'manifest %s: entry in generated-files not present '
                        'elsewhere in manifest: %s' % (path, f), context)

            yield obj
        except (AssertionError, Exception):
            raise SandboxValidationError('Error processing test '
                'manifest file %s: %s' % (path,
                    '\n'.join(traceback.format_exception(*sys.exc_info()))),
                context)

    def _process_reftest_manifest(self, context, flavor, manifest_path, manifest):
        manifest_full_path = manifest_path.full_path
        manifest_reldir = mozpath.dirname(mozpath.relpath(manifest_full_path,
            context.config.topsrcdir))

        # reftest manifests don't come from manifest parser. But they are
        # similar enough that we can use the same emitted objects. Note
        # that we don't perform any installs for reftests.
        obj = TestManifest(context, manifest_full_path, manifest,
                flavor=flavor, install_prefix='%s/' % flavor,
                relpath=mozpath.join(manifest_reldir,
                    mozpath.basename(manifest_path)))

        for test, source_manifest in sorted(manifest.tests):
            obj.tests.append({
                'path': test,
                'here': mozpath.dirname(test),
                'manifest': source_manifest,
                'name': mozpath.basename(test),
                'head': '',
                'support-files': '',
                'subsuite': '',
            })

        yield obj

    def _process_web_platform_tests_manifest(self, context, paths, manifest):
        manifest_path, tests_root = paths
        manifest_full_path = mozpath.normpath(mozpath.join(
            context.srcdir, manifest_path))
        manifest_reldir = mozpath.dirname(mozpath.relpath(manifest_full_path,
            context.config.topsrcdir))
        tests_root = mozpath.normpath(mozpath.join(context.srcdir, tests_root))

        # Create a equivalent TestManifest object
        obj = TestManifest(context, manifest_full_path, manifest,
                           flavor="web-platform-tests",
                           relpath=mozpath.join(manifest_reldir,
                                                mozpath.basename(manifest_path)),
                           install_prefix="web-platform/")


        for test_type, path, tests in manifest:
            path = mozpath.join(tests_root, path)
            if test_type not in ["testharness", "reftest", "wdspec"]:
                continue

            for test in tests:
                obj.tests.append({
                    'path': path,
                    'here': mozpath.dirname(path),
                    'manifest': manifest_path,
                    'name': test.id,
                    'head': '',
                    'support-files': '',
                    'subsuite': '',
                })

        yield obj

    def _process_jar_manifests(self, context):
        jar_manifests = context.get('JAR_MANIFESTS', [])
        if len(jar_manifests) > 1:
            raise SandboxValidationError('While JAR_MANIFESTS is a list, '
                'it is currently limited to one value.', context)

        for path in jar_manifests:
            yield JARManifest(context, path)

        # Temporary test to look for jar.mn files that creep in without using
        # the new declaration. Before, we didn't require jar.mn files to
        # declared anywhere (they were discovered). This will detect people
        # relying on the old behavior.
        if os.path.exists(os.path.join(context.srcdir, 'jar.mn')):
            if 'jar.mn' not in jar_manifests:
                raise SandboxValidationError('A jar.mn exists but it '
                    'is not referenced in the moz.build file. '
                    'Please define JAR_MANIFESTS.', context)

    def _emit_directory_traversal_from_context(self, context):
        o = DirectoryTraversal(context)
        o.dirs = context.get('DIRS', [])

        # Some paths have a subconfigure, yet also have a moz.build. Those
        # shouldn't end up in self._external_paths.
        if o.objdir:
            self._external_paths -= { o.relobjdir }

        yield o