Allow overriding a program with a CustomTarget

Move implementation to a function read to become public API.

Author: xclaesse

docs/yaml/builtins/meson.yaml

@@ -383,6 +383,10 @@ methods:
       check is passed to [[find_program]] for a program that has been overridden with
       an executable, the current project version is used.
 
+      *(since 1.10.0)* It is also possible to override with a [[@custom_tgt]] or
+      [[@custom_idx]]. In that case, be aware that an interpreter could be required
+      on Windows in which case [[local_program]] should be used.
+
     posargs:
       progname:
         type: str

mesonbuild/build.py

@@ -3337,9 +3337,6 @@ def __init__(self, program: T.Union[programs.ExternalProgram, Executable, Custom
                  depends: T.Optional[T.List[T.Union[BuildTarget, CustomTarget]]] = None,
                  depend_files: T.Optional[T.List[File]] = None) -> None:
         super().__init__()
-        if isinstance(program, CustomTarget):
-            if len(program.outputs) != 1:
-                raise InvalidArguments('CustomTarget used as LocalProgram must have exactly one output.')
         self.name = program.name
         self.program = program
         self.depends = list(depends or [])

mesonbuild/interpreter/interpreter.py

@@ -1769,6 +1769,38 @@ def func_find_program(self, node: mparser.BaseNode, args: T.Tuple[T.List[mesonli
                                       silent=False, wanted=kwargs['version'], version_arg=kwargs['version_argument'],
                                       search_dirs=search_dirs)
 
+    def _local_program_impl(self, exe: T.Union[mesonlib.FileOrString, build.Executable, build.CustomTarget, build.CustomTargetIndex],
+                            depends_: T.Optional[T.List[T.Union[build.BuildTarget, build.CustomTarget, build.CustomTargetIndex]]] = None,
+                            depend_files_: T.Optional[T.List[mesonlib.FileOrString]] = None,
+                            interpreter: T.Optional[T.Union[ExternalProgram, T.List[T.Union[ExternalProgram, str]]]] = None) -> build.LocalProgram:
+        if isinstance(exe, build.CustomTarget):
+            if len(exe.outputs) != 1:
+                raise InvalidArguments('CustomTarget used as LocalProgram must have exactly one output.')
+        depends = [d.target if isinstance(d, build.CustomTargetIndex) else d for d in (depends_ or [])]
+        depend_files = self.source_strings_to_files(depend_files_ or [])
+        if isinstance(exe, (str, mesonlib.File)):
+            file = self.source_strings_to_files([exe])[0]
+            abspath = file.absolute_path(self.environment.source_dir, self.environment.build_dir)
+            prog = ExternalProgram(file.fname, command=[abspath], silent=True)
+            return build.LocalProgram(prog, self.project_version, depends, depend_files)
+        if interpreter:
+            if not isinstance(exe, (build.CustomTarget, build.CustomTargetIndex)):
+                raise InvalidArguments('The "interpreter" argument can only be used when the first argument is a custom target.')
+            if isinstance(interpreter, list):
+                interpreter, args = interpreter[0], interpreter[1:]
+                if not isinstance(interpreter, ExternalProgram) or any(not isinstance(a, str) for a in args):
+                    raise InvalidArguments('Interpreter must be an ExternalProgram followed by strings.')
+            else:
+                args = []
+            if not interpreter.found():
+                raise InvalidArguments(f'Specified interpreter program {interpreter.description()!r} not found.')
+            target = exe.target if isinstance(exe, build.CustomTargetIndex) else exe
+            depends.append(target)
+            cmd = interpreter.get_command() + args + [self.backend.get_target_filename(exe)]
+            prog = ExternalProgram(exe.name, command=cmd, silent=True)
+            return build.LocalProgram(prog, self.project_version, depends, depend_files)
+        return build.LocalProgram(exe, self.project_version, depends, depend_files)
+
     # When adding kwargs, please check if they make sense in dependencies.get_dep_identifier()
     @typed_pos_args('dependency', varargs=str, min_varargs=1)
     @typed_kwargs('dependency', *DEPENDENCY_KWS)

mesonbuild/interpreter/mesonmain.py

@@ -315,20 +315,19 @@ def install_dependency_manifest_method(self, args: T.Tuple[str], kwargs: 'TYPE_k
         self.build.dep_manifest_name = args[0]
 
     @FeatureNew('meson.override_find_program', '0.46.0')
-    @typed_pos_args('meson.override_find_program', str, (mesonlib.File, ExternalProgram, build.Executable, build.LocalProgram))
+    @typed_pos_args('meson.override_find_program', str, (mesonlib.File, ExternalProgram, build.Executable, build.LocalProgram,
+                                                         build.CustomTarget, build.CustomTargetIndex))
     @noKwargs
     @InterpreterObject.method('override_find_program')
-    def override_find_program_method(self, args: T.Tuple[str, T.Union[mesonlib.File, ExternalProgram, build.Executable, build.LocalProgram]], kwargs: 'TYPE_kwargs') -> None:
+    def override_find_program_method(self, args: T.Tuple[str, T.Union[mesonlib.File, ExternalProgram, build.Executable,
+                                                                      build.LocalProgram, build.CustomTarget, build.CustomTargetIndex]],
+                                     kwargs: 'TYPE_kwargs') -> None:
         name, exe = args
-        if isinstance(exe, mesonlib.File):
-            abspath = exe.absolute_path(self.interpreter.environment.source_dir,
-                                        self.interpreter.environment.build_dir)
-            if not os.path.exists(abspath):
-                raise InterpreterException(f'Tried to override {name} with a file that does not exist.')
-            prog = ExternalProgram(name, command=[abspath], silent=True)
-            exe = build.LocalProgram(prog, self.interpreter.project_version)
-        elif isinstance(exe, build.Executable):
-            exe = build.LocalProgram(exe, self.interpreter.project_version)
+        if isinstance(exe, (build.CustomTarget, build.CustomTargetIndex)):
+            FeatureNew.single_use('Overriding find_program with a CustomTarget or CustomTargetIndex', '1.10.0',
+                                  self.subproject, location=self.current_node)
+        if not isinstance(exe, (ExternalProgram, build.LocalProgram)):
+            exe = self.interpreter._local_program_impl(exe)
         self.interpreter.add_find_program_override(name, exe)
 
     @typed_kwargs(