Merge pull request #9339 from dcbaker/submit/structured_sources

Structured Sources

32 files changed, 534 insertions, 42 deletions

diff --git a/data/syntax-highlighting/vim/syntax/meson.vim b/data/syntax-highlighting/vim/syntax/meson.vim
index 15b47cd..0519bb2 100644
--- a/data/syntax-highlighting/vim/syntax/meson.vim
+++ b/data/syntax-highlighting/vim/syntax/meson.vim
@@ -116,6 +116,7 @@ syn keyword mesonBuiltin
   \ shared_library
   \ shared_module
   \ static_library
+  \ structured_sources
   \ subdir
   \ subdir_done
   \ subproject
diff --git a/docs/markdown/Rust.md b/docs/markdown/Rust.md
new file mode 100644
index 0000000..b2376c3
--- /dev/null
+++ b/docs/markdown/Rust.md
@@ -0,0 +1,56 @@
+---
+title: Rust
+short-description: Working with Rust in Meson
+---
+
+# Using Rust with Meson
+
+## Mixing Rust and non-Rust sources
+
+Meson currently does not support creating a single target with Rust and non Rust
+sources mixed together, therefore one must compile multiple libraries and link
+them.
+
+```meson
+rust_lib = static_library(
+    'rust_lib',
+    sources : 'lib.rs',
+    ...
+)
+
+c_lib = static_library(
+    'c_lib',
+    sources : 'lib.c',
+    link_with : rust_lib,
+)
+```
+This is an implementation detail of Meson, and is subject to change in the future.
+
+## Mixing Generated and Static sources
+
+*Note* This feature was added in 0.62
+
+You can use a [[structured_source]] for this. Structured sources are a dictionary
+mapping a string of the directory, to a source or list of sources.
+When using a structured source all inputs *must* be listed, as Meson may copy
+the sources from the source tree to the build tree.
+
+Structured inputs are generally not needed when not using generated sources.
+
+As an implementation detail, Meson will attempt to determine if it needs to copy
+files at configure time and will skip copying if it can. Copying is done at
+build time (when necessary), to avoid reconfiguring when sources change.
+
+```meson
+executable(
+    'rust_exe',
+    structured_sources(
+        'main.rs',
+        {
+            'foo' : ['bar.rs', 'foo/lib.rs', generated_rs],
+            'foo/bar' : [...],
+            'other' : [...],
+        }
+    )
+)
+```
diff --git a/docs/markdown/snippets/structured_sources.md b/docs/markdown/snippets/structured_sources.md
new file mode 100644
index 0000000..19fdc86
--- /dev/null
+++ b/docs/markdown/snippets/structured_sources.md
@@ -0,0 +1,26 @@
+## structured_sources()
+
+A new function, `structured_sources()` has been added. This function allows
+languages like Rust which depend on the filesystem layout at compile time to mix
+generated and static sources.
+
+```meson
+executable(
+  'main',
+  structured_sources(
+    'main.rs,
+    {'mod' : generated_mod_rs},
+  )
+)
+```
+
+Meson will then at build time copy the files into the build directory (if
+necessary), so that the desired file structure is laid out, and compile that. In
+this case:
+
+```
+root/
+  main.rs
+  mod/
+    mod.rs
+```
diff --git a/docs/sitemap.txt b/docs/sitemap.txt
index 11b64e0..e562ac7 100644
--- a/docs/sitemap.txt
+++ b/docs/sitemap.txt
@@ -63,6 +63,7 @@ index.md
 		Vala.md
 		D.md
 		Cython.md
+		Rust.md
 		IDE-integration.md
 		Custom-build-targets.md
 		Build-system-converters.md
diff --git a/docs/yaml/functions/_build_target_base.yaml b/docs/yaml/functions/_build_target_base.yaml
index 88fb8ae..87966f6 100644
--- a/docs/yaml/functions/_build_target_base.yaml
+++ b/docs/yaml/functions/_build_target_base.yaml
@@ -49,7 +49,7 @@ kwargs:
       eg: `cpp_args` for C++
 
   sources:
-    type: str | file | custom_tgt | custom_idx | generated_list
+    type: str | file | custom_tgt | custom_idx | generated_list | structured_src
     description: Additional source files. Same as the source varargs.
 
   build_by_default:
diff --git a/docs/yaml/functions/structured_sources.yaml b/docs/yaml/functions/structured_sources.yaml
new file mode 100644
index 0000000..a5f0a83
--- /dev/null
+++ b/docs/yaml/functions/structured_sources.yaml
@@ -0,0 +1,21 @@
+name: structured_sources
+returns: structured_src
+since: 0.62.0
+description: |
+  Create a StructuredSource object, which is opaque and may be passed as a source
+  to any build_target (including static_library, shared_library, executable,
+  etc.). This is useful for languages like Rust, which use the filesystem layout
+  to determine import names. This is only allowed in Rust targets, and cannot be
+  mixed with non structured inputs.
+
+posargs:
+  root:
+    type: list[str | file | custom_tgt | custom_idx | generated_list]
+    description: Sources to put at the root of the generated structure
+
+optargs:
+  additional:
+    type: dict[str | file | custom_tgt | custom_idx | generated_list]
+    description: |
+      Additional sources, where the key is the directory under the root to place
+      the values
diff --git a/docs/yaml/objects/structured_src.yaml b/docs/yaml/objects/structured_src.yaml
new file mode 100644
index 0000000..839575d
--- /dev/null
+++ b/docs/yaml/objects/structured_src.yaml
@@ -0,0 +1,3 @@
+name: structured_src
+long_name: Structured Source
+description: Opaque object returned by [[structured_sources]].
diff --git a/mesonbuild/ast/interpreter.py b/mesonbuild/ast/interpreter.py
index fe11870..e3d3e93 100644
--- a/mesonbuild/ast/interpreter.py
+++ b/mesonbuild/ast/interpreter.py
@@ -156,6 +156,7 @@ class AstInterpreter(InterpreterBase):
                            'alias_target': self.func_do_nothing,
                            'summary': self.func_do_nothing,
                            'range': self.func_do_nothing,
+                           'structured_sources': self.func_do_nothing,
                            })
 
     def _unholder_args(self, args: _T, kwargs: _V) -> T.Tuple[_T, _V]:
diff --git a/mesonbuild/ast/introspection.py b/mesonbuild/ast/introspection.py
index 9bd73d7..af29542 100644
--- a/mesonbuild/ast/introspection.py
+++ b/mesonbuild/ast/introspection.py
@@ -249,7 +249,7 @@ class IntrospectionInterpreter(AstInterpreter):
         objects = []        # type: T.List[T.Any]
         empty_sources = []  # type: T.List[T.Any]
         # Passing the unresolved sources list causes errors
-        target = targetclass(name, self.subdir, self.subproject, for_machine, empty_sources, objects, self.environment, kwargs_reduced)
+        target = targetclass(name, self.subdir, self.subproject, for_machine, empty_sources, [], objects, self.environment, kwargs_reduced)
 
         new_target = {
             'name': target.get_basename(),
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index a66111b..fdd5cd3 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -54,6 +54,7 @@ if T.TYPE_CHECKING:
     from .._typing import ImmutableListProtocol
     from ..linkers import DynamicLinker, StaticLinker
     from ..compilers.cs import CsCompiler
+    from ..interpreter.interpreter import SourceOutputs
 
 
 FORTRAN_INCLUDE_PAT = r"^\s*#?include\s*['\"](\w+\.\w+)['\"]"
@@ -1176,6 +1177,8 @@ class NinjaBackend(backends.Backend):
         self.add_rule(NinjaRule('CUSTOM_COMMAND_DEP', ['$COMMAND'], [], '$DESC',
                                 deps='gcc', depfile='$DEPFILE',
                                 extra='restat = 1'))
+        self.add_rule(NinjaRule('COPY_FILE', self.environment.get_build_command() + ['--internal', 'copy'],
+                                ['$in', '$out'], 'Copying $in to $out'))
 
         c = self.environment.get_build_command() + \
             ['--internal',
@@ -1650,6 +1653,39 @@ class NinjaBackend(backends.Backend):
 
         return static_sources, generated_sources, cython_sources
 
+    def _generate_copy_target(self, src: 'mesonlib.FileOrString', output: Path) -> None:
+        """Create a target to copy a source file from one location to another."""
+        if isinstance(src, File):
+            instr = src.absolute_path(self.environment.source_dir, self.environment.build_dir)
+        else:
+            instr = src
+        elem = NinjaBuildElement(self.all_outputs, [str(output)], 'COPY_FILE', [instr])
+        elem.add_orderdep(instr)
+        self.add_build(elem)
+
+    def __generate_compile_structure(self, target: build.BuildTarget) -> T.Tuple[T.List[str], T.Optional[str]]:
+        first_file: T.Optional[str] = None
+        orderdeps: T.List[str] = []
+        root = Path(self.get_target_private_dir(target)) / 'structured'
+        for path, files in target.structured_sources.sources.items():
+            for file in files:
+                if isinstance(file, (str, File)):
+                    if isinstance(file, str):
+                        file = File.from_absolute_file(file)
+                    out = root / path / Path(file.fname).name
+                    orderdeps.append(str(out))
+                    self._generate_copy_target(file, out)
+                    if first_file is None:
+                        first_file = str(out)
+                else:
+                    for f in file.get_outputs():
+                        out = root / path / f
+                        orderdeps.append(str(out))
+                        self._generate_copy_target(str(Path(file.subdir) / f), out)
+                        if first_file is None:
+                            first_file = str(out)
+        return orderdeps, first_file
+
     def generate_rust_target(self, target: build.BuildTarget) -> None:
         rustc = target.compilers['rust']
         # Rust compiler takes only the main file as input and
@@ -1670,6 +1706,25 @@ class NinjaBackend(backends.Backend):
         orderdeps: T.List[str] = []
 
         main_rust_file = None
+        if target.structured_sources:
+            if target.structured_sources.needs_copy(target):
+                _ods, main_rust_file = self.__generate_compile_structure(target)
+                orderdeps.extend(_ods)
+            else:
+                g = target.structured_sources.first_file()
+                if isinstance(g, str):
+                    g = File.from_source_file(self.environment.source_dir, target.subdir, g)
+
+                if isinstance(g, File):
+                    main_rust_file = g.rel_to_builddir(self.build_to_src)
+                elif isinstance(g, GeneratedList):
+                    main_rust_file = os.path.join(self.get_target_private_dir(target), i)
+                else:
+                    main_rust_file = os.path.join(g.get_subdir(), i)
+                orderdeps.extend([os.path.join(self.build_to_src, target.subdir, s)
+                                  for s in  target.structured_sources.as_list()])
+
+
         for i in target.get_sources():
             if not rustc.can_compile(i):
                 raise InvalidArguments(f'Rust target {target.get_basename()} contains a non-rust source file.')
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 5c1bd32..fbc1618 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -426,7 +426,7 @@ class ExtractedObjects(HoldableObject):
         # Filter out headers and all non-source files
         return [s for s in sources if environment.is_source(s) and not environment.is_header(s)]
 
-    def classify_all_sources(self, sources: T.List[str], generated_sources: T.Sequence['GeneratedTypes']) -> T.Dict['Compiler', T.List['FileOrString']]:
+    def classify_all_sources(self, sources: T.List[FileOrString], generated_sources: T.Sequence['GeneratedTypes']) -> T.Dict['Compiler', T.List['FileOrString']]:
         sources_ = self.get_sources(sources, generated_sources)
         return classify_unity_sources(self.target.compilers.values(), sources_)
 
@@ -452,10 +452,65 @@ class ExtractedObjects(HoldableObject):
             for source in self.get_sources(self.srclist, self.genlist)
         ]
 
+
+@dataclass(eq=False, order=False)
+class StructuredSources(HoldableObject):
+
+    """A container for sources in languages that use filesystem hierarchy.
+
+    Languages like Rust and Cython rely on the layout of files in the filesystem
+    as part of the compiler implementation. This structure allows us to
+    represent the required filesystem layout.
+    """
+
+    sources: T.DefaultDict[str, T.List[T.Union[str, File, CustomTarget, CustomTargetIndex, GeneratedList]]] = field(
+        default_factory=lambda: defaultdict(list))
+
+    def __add__(self, other: StructuredSources) -> StructuredSources:
+        sources = self.sources.copy()
+        for k, v in other.sources.items():
+            sources[k].extend(v)
+        return StructuredSources(sources)
+
+    def __bool__(self) -> bool:
+        return bool(self.sources)
+
+    def first_file(self) -> T.Union[str, File, CustomTarget, CustomTargetIndex, GeneratedList]:
+        """Get the first source in the root
+
+        :return: The first source in the root
+        """
+        return self.sources[''][0]
+
+    def as_list(self) -> T.List[T.Union[str, File, CustomTarget, CustomTargetIndex, GeneratedList]]:
+        return list(itertools.chain.from_iterable(self.sources.values()))
+
+    def needs_copy(self, target: BuildTarget) -> bool:
+        """Do we need to create a structure in the build directory.
+
+        This allows us to avoid making copies if the structures exists in the
+        source dir. Which could happen in situations where a generated source
+        only exists in some configurations
+        """
+        p = pathlib.Path(target.subdir)
+        for files in self.sources.values():
+            for f in files:
+                if isinstance(f, str):
+                    if not (target.environment.source_dir / p / f).exists():
+                        return True
+                elif isinstance(f, File):
+                    if f.is_built:
+                        return True
+                else:
+                    return True
+        return False
+
+
 EnvInitValueType = T.Dict[str, T.Union[str, T.List[str]]]
 
+
 class EnvironmentVariables(HoldableObject):
-    def __init__(self, values: T.Optional[EnvValueType] = None,
+    def __init__(self, values: T.Optional[EnvInitValueType] = None,
                  init_method: Literal['set', 'prepend', 'append'] = 'set', separator: str = os.pathsep) -> None:
         self.envvars: T.List[T.Tuple[T.Callable[[T.Dict[str, str], str, T.List[str], str], str], str, T.List[str], str]] = []
         # The set of all env vars we have operations for. Only used for self.has_name()
@@ -684,14 +739,16 @@ class BuildTarget(Target):
 
     install_dir: T.List[T.Union[str, bool]]
 
-    def __init__(self, name: str, subdir: str, subproject: 'SubProject', for_machine: MachineChoice,
-                 sources: T.List['SourceOutputs'], objects, environment: environment.Environment, kwargs):
+    def __init__(self, name: str, subdir: str, subproject: SubProject, for_machine: MachineChoice,
+                 sources: T.List['SourceOutputs'], structured_sources: T.Optional[StructuredSources],
+                 objects, environment: environment.Environment, kwargs):
         super().__init__(name, subdir, subproject, True, for_machine)
         unity_opt = environment.coredata.get_option(OptionKey('unity'))
         self.is_unity = unity_opt == 'on' or (unity_opt == 'subprojects' and subproject != '')
         self.environment = environment
         self.compilers = OrderedDict() # type: OrderedDict[str, Compiler]
         self.objects: T.List[T.Union[str, 'File', 'ExtractedObjects']] = []
+        self.structured_sources = structured_sources
         self.external_deps: T.List[dependencies.Dependency] = []
         self.include_dirs: T.List['IncludeDirs'] = []
         self.link_language = kwargs.get('link_language')
@@ -723,13 +780,18 @@ class BuildTarget(Target):
         self.process_kwargs(kwargs, environment)
         self.check_unknown_kwargs(kwargs)
         self.process_compilers()
-        if not any([self.sources, self.generated, self.objects, self.link_whole]):
+        if not any([self.sources, self.generated, self.objects, self.link_whole, self.structured_sources]):
             raise InvalidArguments(f'Build target {name} has no sources.')
         self.process_compilers_late()
         self.validate_sources()
         self.validate_install(environment)
         self.check_module_linking()
 
+        if self.structured_sources and any([self.sources, self.generated]):
+            raise MesonException('cannot mix structured sources and unstructured sources')
+        if self.structured_sources and 'rust' not in self.compilers:
+            raise MesonException('structured sources are only supported in Rust targets')
+
     def __repr__(self):
         repr_str = "<{0} {1}: {2}>"
         return repr_str.format(self.__class__.__name__, self.get_id(), self.filename)
@@ -833,21 +895,31 @@ class BuildTarget(Target):
                     self.compilers[lang] = compilers[lang]
                     break
 
-    def process_compilers(self):
+    def process_compilers(self) -> None:
         '''
         Populate self.compilers, which is the list of compilers that this
         target will use for compiling all its sources.
         We also add compilers that were used by extracted objects to simplify
         dynamic linker determination.
         '''
-        if not self.sources and not self.generated and not self.objects:
+        if not any([self.sources, self.generated, self.objects, self.structured_sources]):
             return
         # Populate list of compilers
         compilers = self.environment.coredata.compilers[self.for_machine]
         # Pre-existing sources
-        sources = list(self.sources)
+        sources: T.List['FileOrString'] = list(self.sources)
+        generated = self.generated.copy()
+
+        if self.structured_sources:
+            for v in self.structured_sources.sources.values():
+                for src in v:
+                    if isinstance(src, (str, File)):
+                        sources.append(src)
+                    else:
+                        generated.append(src)
+
         # All generated sources
-        for gensrc in self.generated:
+        for gensrc in generated:
             for s in gensrc.get_outputs():
                 # Generated objects can't be compiled, so don't use them for
                 # compiler detection. If our target only has generated objects,
@@ -1571,6 +1643,16 @@ You probably should put it in link_with instead.''')
         elif self.generated:
             if self.generated[0].get_outputs()[0].endswith('.rs'):
                 return True
+        elif self.structured_sources:
+            for v in self.structured_sources.sources.values():
+                for s in v:
+                    if isinstance(s, (str, File)):
+                        if s.endswith('.rs'):
+                            return True
+                    else:
+                        for ss in s.get_outputs():
+                            if ss.endswith('.rs'):
+                                return True
         return False
 
     def get_using_msvc(self) -> bool:
@@ -1772,12 +1854,13 @@ class Executable(BuildTarget):
     known_kwargs = known_exe_kwargs
 
     def __init__(self, name: str, subdir: str, subproject: str, for_machine: MachineChoice,
-                 sources: T.List[File], objects, environment: environment.Environment, kwargs):
+                 sources: T.List[File], structured_sources: T.Optional['StructuredSources'],
+                 objects, environment: environment.Environment, kwargs):
         self.typename = 'executable'
         key = OptionKey('b_pie')
         if 'pie' not in kwargs and key in environment.coredata.options:
             kwargs['pie'] = environment.coredata.options[key].value
-        super().__init__(name, subdir, subproject, for_machine, sources, objects, environment, kwargs)
+        super().__init__(name, subdir, subproject, for_machine, sources, structured_sources, objects, environment, kwargs)
         # Unless overridden, executables have no suffix or prefix. Except on
         # Windows and with C#/Mono executables where the suffix is 'exe'
         if not hasattr(self, 'prefix'):
@@ -1897,9 +1980,11 @@ class Executable(BuildTarget):
 class StaticLibrary(BuildTarget):
     known_kwargs = known_stlib_kwargs
 
-    def __init__(self, name, subdir, subproject, for_machine: MachineChoice, sources, objects, environment, kwargs):
+    def __init__(self, name: str, subdir: str, subproject: str, for_machine: MachineChoice,
+                 sources: T.List[File], structured_sources: T.Optional['StructuredSources'],
+                 objects, environment: environment.Environment, kwargs):
         self.typename = 'static library'
-        super().__init__(name, subdir, subproject, for_machine, sources, objects, environment, kwargs)
+        super().__init__(name, subdir, subproject, for_machine, sources, structured_sources, objects, environment, kwargs)
         if 'cs' in self.compilers:
             raise InvalidArguments('Static libraries not supported for C#.')
         if 'rust' in self.compilers:
@@ -1958,7 +2043,9 @@ class StaticLibrary(BuildTarget):
 class SharedLibrary(BuildTarget):
     known_kwargs = known_shlib_kwargs
 
-    def __init__(self, name, subdir, subproject, for_machine: MachineChoice, sources, objects, environment, kwargs):
+    def __init__(self, name: str, subdir: str, subproject: str, for_machine: MachineChoice,
+                 sources: T.List[File], structured_sources: T.Optional['StructuredSources'],
+                 objects, environment: environment.Environment, kwargs):
         self.typename = 'shared library'
         self.soversion = None
         self.ltversion = None
@@ -1975,7 +2062,7 @@ class SharedLibrary(BuildTarget):
         self.debug_filename = None
         # Use by the pkgconfig module
         self.shared_library_only = False
-        super().__init__(name, subdir, subproject, for_machine, sources, objects, environment, kwargs)
+        super().__init__(name, subdir, subproject, for_machine, sources, structured_sources, objects, environment, kwargs)
         if 'rust' in self.compilers:
             # If no crate type is specified, or it's the generic lib type, use dylib
             if not hasattr(self, 'rust_crate_type') or self.rust_crate_type == 'lib':
@@ -2285,12 +2372,15 @@ class SharedLibrary(BuildTarget):
 class SharedModule(SharedLibrary):
     known_kwargs = known_shmod_kwargs
 
-    def __init__(self, name, subdir, subproject, for_machine: MachineChoice, sources, objects, environment, kwargs):
+    def __init__(self, name: str, subdir: str, subproject: str, for_machine: MachineChoice,
+                 sources: T.List[File], structured_sources: T.Optional['StructuredSources'],
+                 objects, environment: environment.Environment, kwargs):
         if 'version' in kwargs:
             raise MesonException('Shared modules must not specify the version kwarg.')
         if 'soversion' in kwargs:
             raise MesonException('Shared modules must not specify the soversion kwarg.')
-        super().__init__(name, subdir, subproject, for_machine, sources, objects, environment, kwargs)
+        super().__init__(name, subdir, subproject, for_machine, sources,
+                         structured_sources, objects, environment, kwargs)
         self.typename = 'shared module'
         # We need to set the soname in cases where build files link the module
         # to build targets, see: https://github.com/mesonbuild/meson/issues/9492
@@ -2610,15 +2700,19 @@ class AliasTarget(RunTarget):
 class Jar(BuildTarget):
     known_kwargs = known_jar_kwargs
 
-    def __init__(self, name, subdir, subproject, for_machine: MachineChoice, sources, objects, environment, kwargs):
+    def __init__(self, name: str, subdir: str, subproject: str, for_machine: MachineChoice,
+                 sources: T.List[File], structured_sources: T.Optional['StructuredSources'],
+                 objects, environment: environment.Environment, kwargs):
         self.typename = 'jar'
-        super().__init__(name, subdir, subproject, for_machine, sources, objects, environment, kwargs)
+        super().__init__(name, subdir, subproject, for_machine, sources, structured_sources, objects, environment, kwargs)
         for s in self.sources:
             if not s.endswith('.java'):
                 raise InvalidArguments(f'Jar source {s} is not a java file.')
         for t in self.link_targets:
             if not isinstance(t, Jar):
                 raise InvalidArguments(f'Link target {t} is not a jar target.')
+        if self.structured_sources:
+            raise InvalidArguments(f'structured sources are not supported in Java targets.')
         self.filename = self.name + '.jar'
         self.outputs = [self.filename]
         self.java_args = kwargs.get('java_args', [])
diff --git a/mesonbuild/dependencies/base.py b/mesonbuild/dependencies/base.py
index c5c62d5..7b85159 100644
--- a/mesonbuild/dependencies/base.py
+++ b/mesonbuild/dependencies/base.py
@@ -14,6 +14,8 @@
 
 # This file contains the detection logic for external dependencies.
 # Custom logic for several other packages are in separate files.
+
+from __future__ import annotations
 import copy
 import os
 import collections
@@ -29,6 +31,7 @@ from ..mesonlib import version_compare_many
 
 if T.TYPE_CHECKING:
     from .._typing import ImmutableListProtocol
+    from ..build import StructuredSources
     from ..compilers.compilers import Compiler
     from ..environment import Environment
     from ..interpreterbase import FeatureCheckBase
@@ -91,7 +94,7 @@ class Dependency(HoldableObject):
         # Raw -L and -l arguments without manual library searching
         # If None, self.link_args will be used
         self.raw_link_args: T.Optional[T.List[str]] = None
-        self.sources: T.List[T.Union['FileOrString', 'CustomTarget']] = []
+        self.sources: T.List[T.Union['FileOrString', 'CustomTarget', 'StructuredSources']] = []
         self.include_type = self._process_include_type_kw(kwargs)
         self.ext_deps: T.List[Dependency] = []
         self.d_features: T.DefaultDict[str, T.List[T.Any]] = collections.defaultdict(list)
@@ -148,7 +151,7 @@ class Dependency(HoldableObject):
     def found(self) -> bool:
         return self.is_found
 
-    def get_sources(self) -> T.List[T.Union['FileOrString', 'CustomTarget']]:
+    def get_sources(self) -> T.List[T.Union['FileOrString', 'CustomTarget', 'StructuredSources']]:
         """Source files that need to be added to the target.
         As an example, gtest-all.cc when using GTest."""
         return self.sources
@@ -228,7 +231,7 @@ class InternalDependency(Dependency):
                  link_args: T.List[str],
                  libraries: T.List[T.Union['BuildTarget', 'CustomTarget']],
                  whole_libraries: T.List[T.Union['BuildTarget', 'CustomTarget']],
-                 sources: T.Sequence[T.Union['FileOrString', 'CustomTarget']],
+                 sources: T.Sequence[T.Union['FileOrString', 'CustomTarget', StructuredSources]],
                  ext_deps: T.List[Dependency], variables: T.Dict[str, T.Any],
                  d_module_versions: T.List[str], d_import_dirs: T.List['IncludeDirs']):
         super().__init__(DependencyTypeName('internal'), {})
diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index a44d02d..27f4c69 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -106,7 +106,7 @@ if T.TYPE_CHECKING:
     # Input source types passed to the build.Target classes
     SourceOutputs = T.Union[mesonlib.File, build.GeneratedList,
                             build.BuildTarget, build.CustomTargetIndex, build.CustomTarget,
-                            build.ExtractedObjects, build.GeneratedList]
+                            build.ExtractedObjects, build.GeneratedList, build.StructuredSources]
 
 
 def _project_version_validator(value: T.Union[T.List, str, mesonlib.File, None]) -> T.Optional[str]:
@@ -386,6 +386,7 @@ class Interpreter(InterpreterBase, HoldableObject):
                            'run_command': self.func_run_command,
                            'run_target': self.func_run_target,
                            'set_variable': self.func_set_variable,
+                           'structured_sources': self.func_structured_sources,
                            'subdir': self.func_subdir,
                            'shared_library': self.func_shared_lib,
                            'shared_module': self.func_shared_module,
@@ -439,6 +440,7 @@ class Interpreter(InterpreterBase, HoldableObject):
             build.InstallDir: OBJ.InstallDirHolder,
             build.IncludeDirs: OBJ.IncludeDirsHolder,
             build.EnvironmentVariables: OBJ.EnvironmentVariablesHolder,
+            build.StructuredSources: OBJ.StructuredSourcesHolder,
             compilers.RunResult: compilerOBJ.TryRunResultHolder,
             dependencies.ExternalLibrary: OBJ.ExternalLibraryHolder,
             coredata.UserFeatureOption: OBJ.FeatureOptionHolder,
@@ -2110,6 +2112,31 @@ external dependencies (including libraries) must go to "dependencies".''')
         self.build.symlinks.append(l)
         return l
 
+    @FeatureNew('structured_sources', '0.62.0')
+    @typed_pos_args('structured_sources', object, optargs=[dict])
+    @noKwargs
+    @noArgsFlattening
+    def func_structured_sources(
+            self, node: mparser.BaseNode,
+            args: T.Tuple[object, T.Optional[T.Dict[str, object]]],
+            kwargs: 'TYPE_kwargs') -> build.StructuredSources:
+        valid_types = (str, mesonlib.File, build.GeneratedList, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList)
+        sources: T.Dict[str, T.List[T.Union['mesonlib.FileOrString', 'build.GeneratedTypes']]] = collections.defaultdict(list)
+
+        for arg in mesonlib.listify(args[0]):
+            if not isinstance(arg, valid_types):
+                raise InvalidArguments(f'structured_sources: type "{type(arg)}" is not valid')
+            sources[''].append(arg)
+        if args[1]:
+            if '' in args[1]:
+                raise InvalidArguments('structured_sources: keys to dictionary argument may not be an empty string.')
+            for k, v in args[1].items():
+                for arg in mesonlib.listify(v):
+                    if not isinstance(arg, valid_types):
+                        raise InvalidArguments(f'structured_sources: type "{type(arg)}" is not valid')
+                    sources[k].append(arg)
+        return build.StructuredSources(sources)
+
     @typed_pos_args('subdir', str)
     @typed_kwargs(
         'subdir',
@@ -2757,7 +2784,7 @@ Try setting b_lundef to false instead.'''.format(self.coredata.options[OptionKey
                 results.append(s)
             elif isinstance(s, (build.GeneratedList, build.BuildTarget,
                                 build.CustomTargetIndex, build.CustomTarget,
-                                build.ExtractedObjects)):
+                                build.ExtractedObjects, build.StructuredSources)):
                 results.append(s)
             else:
                 raise InterpreterException(f'Source item is {s!r} instead of '
@@ -2840,7 +2867,7 @@ Try setting b_lundef to false instead.'''.format(self.coredata.options[OptionKey
         else:
             raise InterpreterException(f'Unknown default_library value: {default_library}.')
 
-    def build_target(self, node, args, kwargs, targetclass):
+    def build_target(self, node: mparser.BaseNode, args, kwargs, targetclass):
         @FeatureNewKwargs('build target', '0.42.0', ['rust_crate_type', 'build_rpath', 'implicit_include_directories'])
         @FeatureNewKwargs('build target', '0.41.0', ['rust_args'])
         @FeatureNewKwargs('build target', '0.40.0', ['build_by_default'])
@@ -2873,8 +2900,39 @@ Try setting b_lundef to false instead.'''.format(self.coredata.options[OptionKey
         # passed to library() when default_library == 'static'.
         kwargs = {k: v for k, v in kwargs.items() if k in targetclass.known_kwargs}
 
+        srcs: T.List['SourceInputs'] = []
+        struct: T.Optional[build.StructuredSources] = build.StructuredSources()
+        for s in sources:
+            if isinstance(s, build.StructuredSources):
+                struct = struct + s
+            else:
+                srcs.append(s)
+
+        if not struct:
+            struct = None
+        else:
+            # Validate that we won't end up with two outputs with the same name.
+            # i.e, don't allow:
+            # [structured_sources('foo/bar.rs'), structured_sources('bar/bar.rs')]
+            for v in struct.sources.values():
+                outputs: T.Set[str] = set()
+                for f in v:
+                    o: T.List[str]
+                    if isinstance(f, str):
+                        o = [os.path.basename(f)]
+                    elif isinstance(f, mesonlib.File):
+                        o = [f.fname]
+                    else:
+                        o = f.get_outputs()
+                    conflicts = outputs.intersection(o)
+                    if conflicts:
+                        raise InvalidArguments.from_node(
+                            f"Conflicting sources in structured sources: {', '.join(sorted(conflicts))}",
+                            node=node)
+                    outputs.update(o)
+
         kwargs['include_directories'] = self.extract_incdirs(kwargs)
-        target = targetclass(name, self.subdir, self.subproject, for_machine, sources, objs, self.environment, kwargs)
+        target = targetclass(name, self.subdir, self.subproject, for_machine, srcs, struct, objs, self.environment, kwargs)
         target.project_version = self.project_version
 
         self.add_stdlib_info(target)
diff --git a/mesonbuild/interpreter/interpreterobjects.py b/mesonbuild/interpreter/interpreterobjects.py
index 570e031..bf668f3 100644
--- a/mesonbuild/interpreter/interpreterobjects.py
+++ b/mesonbuild/interpreter/interpreterobjects.py
@@ -978,3 +978,9 @@ class GeneratorHolder(ObjectHolder[build.Generator]):
                                             preserve_path_from, extra_args=kwargs['extra_args'])
 
         return gl
+
+
+class StructuredSourcesHolder(ObjectHolder[build.StructuredSources]):
+
+    def __init__(self, sources: build.StructuredSources, interp: 'Interpreter'):
+        super().__init__(sources, interp)
diff --git a/mesonbuild/mesonlib/universal.py b/mesonbuild/mesonlib/universal.py
index c7cb561..d4f51c1 100644
--- a/mesonbuild/mesonlib/universal.py
+++ b/mesonbuild/mesonlib/universal.py
@@ -41,6 +41,7 @@ if T.TYPE_CHECKING:
     from ..build import ConfigurationData
     from ..coredata import KeyedOptionDictType, UserOption
     from ..compilers.compilers import Compiler
+    from ..mparser import BaseNode
 
 FileOrString = T.Union['File', str]
 
@@ -171,6 +172,15 @@ class MesonException(Exception):
         self.lineno = lineno
         self.colno = colno
 
+    @classmethod
+    def from_node(cls, *args: object, node: BaseNode) -> MesonException:
+        """Create a MesonException with location data from a BaseNode
+
+        :param node: A BaseNode to set location data from
+        :return: A Meson Exception instance
+        """
+        return cls(*args, file=node.filename, lineno=node.lineno, colno=node.colno)
+
 
 class MesonBugException(MesonException):
     '''Exceptions thrown when there is a clear Meson bug that should be reported'''
diff --git a/mesonbuild/modules/gnome.py b/mesonbuild/modules/gnome.py
index 2dbfb29..f908a83 100644
--- a/mesonbuild/modules/gnome.py
+++ b/mesonbuild/modules/gnome.py
@@ -607,10 +607,10 @@ class GnomeModule(ExtensionModule):
 
     def _get_link_args(self, state: 'ModuleState',
                        lib: T.Union[build.SharedLibrary, build.StaticLibrary],
-                       depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString']],
+                       depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]],
                        include_rpath: bool = False,
                        use_gir_args: bool = False
-                       ) -> T.Tuple[T.List[str], T.List[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString']]]:
+                       ) -> T.Tuple[T.List[str], T.List[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]]]:
         link_command: T.List[str] = []
         new_depends = list(depends)
         # Construct link args
@@ -638,12 +638,12 @@ class GnomeModule(ExtensionModule):
     def _get_dependencies_flags(
             self, deps: T.Sequence[T.Union['Dependency', build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]],
             state: 'ModuleState',
-            depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString']],
+            depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]],
             include_rpath: bool = False,
             use_gir_args: bool = False,
             separate_nodedup: bool = False
             ) -> T.Tuple[OrderedSet[str], OrderedSet[str], OrderedSet[str], T.Optional[T.List[str]], OrderedSet[str],
-                         T.List[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString']]]:
+                         T.List[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]]]:
         cflags: OrderedSet[str] = OrderedSet()
         internal_ldflags: OrderedSet[str] = OrderedSet()
         external_ldflags: OrderedSet[str] = OrderedSet()
@@ -931,7 +931,7 @@ class GnomeModule(ExtensionModule):
             girfile: str,
             scan_command: T.Sequence[T.Union['FileOrString', Executable, ExternalProgram, OverrideProgram]],
             generated_files: T.Sequence[T.Union[str, mesonlib.File, build.CustomTarget, build.CustomTargetIndex, build.GeneratedList]],
-            depends: T.Sequence[T.Union['FileOrString', build.BuildTarget, 'build.GeneratedTypes']],
+            depends: T.Sequence[T.Union['FileOrString', build.BuildTarget, 'build.GeneratedTypes', build.StructuredSources]],
             kwargs: T.Dict[str, T.Any]) -> GirTarget:
         install = kwargs['install_gir']
         if install is None:
@@ -989,8 +989,8 @@ class GnomeModule(ExtensionModule):
     def _gather_typelib_includes_and_update_depends(
             state: 'ModuleState',
             deps: T.Sequence[T.Union[Dependency, build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]],
-            depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString']]
-            ) -> T.Tuple[T.List[str], T.List[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString']]]:
+            depends: T.Sequence[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]]
+            ) -> T.Tuple[T.List[str], T.List[T.Union[build.BuildTarget, 'build.GeneratedTypes', 'FileOrString', build.StructuredSources]]]:
         # Need to recursively add deps on GirTarget sources from our
         # dependencies and also find the include directories needed for the
         # typelib generation custom target below.
@@ -1092,7 +1092,7 @@ class GnomeModule(ExtensionModule):
         srcdir = os.path.join(state.environment.get_source_dir(), state.subdir)
         builddir = os.path.join(state.environment.get_build_dir(), state.subdir)
 
-        depends: T.List[T.Union['FileOrString', 'build.GeneratedTypes', build.BuildTarget]] = []
+        depends: T.List[T.Union['FileOrString', 'build.GeneratedTypes', build.BuildTarget, build.StructuredSources]] = []
         depends.extend(gir_dep.sources)
         depends.extend(girtargets)
 
diff --git a/mesonbuild/modules/unstable_rust.py b/mesonbuild/modules/unstable_rust.py
index 501273f..f656cd8 100644
--- a/mesonbuild/modules/unstable_rust.py
+++ b/mesonbuild/modules/unstable_rust.py
@@ -17,7 +17,7 @@ import typing as T
 
 from . import ExtensionModule, ModuleReturnValue
 from .. import mlog
-from ..build import BothLibraries, BuildTarget, CustomTargetIndex, Executable, ExtractedObjects, GeneratedList, IncludeDirs, CustomTarget
+from ..build import BothLibraries, BuildTarget, CustomTargetIndex, Executable, ExtractedObjects, GeneratedList, IncludeDirs, CustomTarget, StructuredSources
 from ..dependencies import Dependency, ExternalLibrary
 from ..interpreter.interpreter import TEST_KWARGS
 from ..interpreterbase import ContainerTypeInfo, InterpreterException, KwargInfo, FeatureNew, typed_kwargs, typed_pos_args, noPosargs
@@ -149,10 +149,9 @@ class RustModule(ExtensionModule):
         new_target_kwargs['dependencies'] = new_target_kwargs.get('dependencies', []) + dependencies
 
         new_target = Executable(
-            name, base_target.subdir, state.subproject,
-            base_target.for_machine, base_target.sources,
-            base_target.objects, base_target.environment,
-            new_target_kwargs
+            name, base_target.subdir, state.subproject, base_target.for_machine,
+            base_target.sources, base_target.structured_sources,
+            base_target.objects, base_target.environment, new_target_kwargs
         )
 
         test = self.interpreter.make_test(
@@ -203,7 +202,7 @@ class RustModule(ExtensionModule):
         name: str
         if isinstance(header, File):
             name = header.fname
-        elif isinstance(header, (BuildTarget, BothLibraries, ExtractedObjects)):
+        elif isinstance(header, (BuildTarget, BothLibraries, ExtractedObjects, StructuredSources)):
             raise InterpreterException('bindgen source file must be a C header, not an object or build target')
         else:
             name = header.get_outputs()[0]
diff --git a/mesonbuild/scripts/copy.py b/mesonbuild/scripts/copy.py
new file mode 100644
index 0000000..acef2a8
--- /dev/null
+++ b/mesonbuild/scripts/copy.py
@@ -0,0 +1,18 @@
+# SPDX-License-Identifer: Apache-2.0
+# Copyright © 2021 Intel Corporation
+
+"""Helper script to copy files at build time.
+
+This is easier than trying to detect whether to use copy, cp, or something else.
+"""
+
+import shutil
+import typing as T
+
+
+def run(args: T.List[str]) -> int:
+    try:
+        shutil.copy2(args[0], args[1])
+    except Exception:
+        return 1
+    return 0
diff --git a/test cases/failing/121 structured source empty string/main.rs b/test cases/failing/121 structured source empty string/main.rs
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/test cases/failing/121 structured source empty string/main.rs
diff --git a/test cases/failing/121 structured source empty string/meson.build b/test cases/failing/121 structured source empty string/meson.build
new file mode 100644
index 0000000..0715991
--- /dev/null
+++ b/test cases/failing/121 structured source empty string/meson.build
@@ -0,0 +1,13 @@
+project('structured_source with empty string key')
+
+if not add_languages(['rust'], required : false, native : false)
+  error('MESON_SKIP_TEST: Rust is required but not found.')
+endif
+
+executable(
+  'main',
+  structured_sources(
+    'main.rs',
+    {'' : 'main.rs'},
+  )
+)
diff --git a/test cases/failing/121 structured source empty string/test.json b/test cases/failing/121 structured source empty string/test.json
new file mode 100644
index 0000000..feb2af9
--- /dev/null
+++ b/test cases/failing/121 structured source empty string/test.json
@@ -0,0 +1,7 @@
+{
+    "stdout": [
+        {
+            "line": "test cases/failing/121 structured source empty string/meson.build:7:0: ERROR: structured_sources: keys to dictionary argument may not be an empty string."
+        }
+    ]
+}
diff --git a/test cases/failing/122 structured_sources conflicts/main.rs b/test cases/failing/122 structured_sources conflicts/main.rs
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/test cases/failing/122 structured_sources conflicts/main.rs
diff --git a/test cases/failing/122 structured_sources conflicts/meson.build b/test cases/failing/122 structured_sources conflicts/meson.build
new file mode 100644
index 0000000..561ad86
--- /dev/null
+++ b/test cases/failing/122 structured_sources conflicts/meson.build
@@ -0,0 +1,17 @@
+project('structured_source with empty string key')
+
+if not add_languages(['rust'], required : false, native : false)
+  error('MESON_SKIP_TEST: Rust is required but not found.')
+endif
+
+executable(
+  'main',
+  [
+    structured_sources(
+      'main.rs',
+    ),
+    structured_sources(
+      'main.rs',
+    ),
+  ],
+)
diff --git a/test cases/failing/122 structured_sources conflicts/test.json b/test cases/failing/122 structured_sources conflicts/test.json
new file mode 100644
index 0000000..4833f86
--- /dev/null
+++ b/test cases/failing/122 structured_sources conflicts/test.json
@@ -0,0 +1,7 @@
+{
+    "stdout": [
+        {
+            "line": "test cases/failing/122 structured_sources conflicts/meson.build:7:0: ERROR: Conflicting sources in structured sources: main.rs"
+        }
+    ]
+}
diff --git a/test cases/rust/18 structured sources/gen.py b/test cases/rust/18 structured sources/gen.py
new file mode 100755
index 0000000..16e5c04
--- /dev/null
+++ b/test cases/rust/18 structured sources/gen.py
@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+
+import argparse
+import textwrap
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('output')
+    args = parser.parse_args()
+
+    with open(args.output, 'w') as f:
+        f.write(textwrap.dedent('''\
+            pub fn bar() -> () {
+                println!("Hello, World!");
+            }'''))
+
+
+if __name__ == "__main__":
+    main()
diff --git a/test cases/rust/18 structured sources/meson.build b/test cases/rust/18 structured sources/meson.build
new file mode 100644
index 0000000..8fa0443
--- /dev/null
+++ b/test cases/rust/18 structured sources/meson.build
@@ -0,0 +1,39 @@
+project('structured input', 'rust')
+
+foo_mod_rs = configure_file(
+  input : 'src/foo.rs.in',
+  output : 'mod.rs',
+  configuration : {'message' : 'Hello, World!'},
+)
+
+conf_file = executable(
+  'main_conf_file',
+  structured_sources(
+    'src/main.rs',
+    {'foo' : [foo_mod_rs]},
+  ),
+)
+
+ct = custom_target(
+  'foo.rs',
+  output : 'foo.rs',
+  command : ['gen.py', '@OUTPUT@'],
+)
+
+target = executable(
+  'main_custom_target',
+  structured_sources(
+    ['src/main.rs', ct],
+  ),
+)
+
+# Should not be coppied
+executable(
+  'no_copy_target',
+  structured_sources(
+    ['src2/main-unique.rs'],
+    {'foo': 'src2/foo/mod.rs'},
+  ),
+)
+
+test('no-copy', find_program('no_copy_test.py'), args : meson.current_build_dir())
diff --git a/test cases/rust/18 structured sources/no_copy_test.py b/test cases/rust/18 structured sources/no_copy_test.py
new file mode 100755
index 0000000..91506b2
--- /dev/null
+++ b/test cases/rust/18 structured sources/no_copy_test.py
@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+
+import argparse
+import os
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('builddir')
+    args = parser.parse_args()
+
+    for _, _, files in os.walk(args.builddir):
+        if 'main-unique.rs' in files:
+            exit(1)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/test cases/rust/18 structured sources/src/foo.rs.in b/test cases/rust/18 structured sources/src/foo.rs.in
new file mode 100644
index 0000000..4f3fc42
--- /dev/null
+++ b/test cases/rust/18 structured sources/src/foo.rs.in
@@ -0,0 +1,4 @@
+
+pub fn bar() -> () {
+    println!("@message@");
+}
diff --git a/test cases/rust/18 structured sources/src/main.rs b/test cases/rust/18 structured sources/src/main.rs
new file mode 100644
index 0000000..3ffeee2
--- /dev/null
+++ b/test cases/rust/18 structured sources/src/main.rs
@@ -0,0 +1,5 @@
+mod foo;
+
+fn main() {
+    foo::bar();
+}
diff --git a/test cases/rust/18 structured sources/src2/foo/mod.rs b/test cases/rust/18 structured sources/src2/foo/mod.rs
new file mode 100644
index 0000000..9463d95
--- /dev/null
+++ b/test cases/rust/18 structured sources/src2/foo/mod.rs
@@ -0,0 +1,4 @@
+
+pub fn bar() -> () {
+    println!("Hello, World!");
+}
diff --git a/test cases/rust/18 structured sources/src2/main-unique.rs b/test cases/rust/18 structured sources/src2/main-unique.rs
new file mode 100644
index 0000000..3ffeee2
--- /dev/null
+++ b/test cases/rust/18 structured sources/src2/main-unique.rs
@@ -0,0 +1,5 @@
+mod foo;
+
+fn main() {
+    foo::bar();
+}
diff --git a/unittests/allplatformstests.py b/unittests/allplatformstests.py
index 6efff61..5a533a9 100644
--- a/unittests/allplatformstests.py
+++ b/unittests/allplatformstests.py
@@ -4000,6 +4000,7 @@ class AllPlatformTests(BasePlatformTests):
         def output_name(name, type_):
             return type_(name=name, subdir=None, subproject=None,
                          for_machine=MachineChoice.HOST, sources=[],
+                         structured_sources=None,
                          objects=[], environment=env, kwargs={}).filename
 
         shared_lib_name = lambda name: output_name(name, SharedLibrary)