vala: Add method to get generated GIR from a build_target

Fixes: #2296
Fixes: #4481
Fixes: #5968

Author: dcbaker

docs/markdown/Vala.md

@@ -318,6 +318,7 @@ foo_h = foo_lib.vala_header()
 This header can now be used like any other generated header to create an
 order-only dependency.
 
+
 ### Depending on VAPI header
 
 *(since 1.10.0)*
@@ -329,6 +330,15 @@ foo_lib = shared_library(...)
 foo_vapi = foo_lib.vala_vapi()
 ```
 
+### Depending on generated GIR
+
+*(since 1.10.0)*
+
+```meson
+foo_lib = shared_library(..., vala_gir : 'foo.gir')
+foo_gir = foo_lib.vala_gir()
+```
+
 ### GObject Introspection and language bindings
 
 A 'binding' allows another programming language to use a library
@@ -363,6 +373,21 @@ directory (i.e. `share/gir-1.0` for GIRs). The fourth element in the
 To then generate a typelib file use a custom target with the
 `g-ir-compiler` program and a dependency on the library:
 
+Since Meson 1.10, use the `.vala_gir()` method to get a handle to the generated `.gir` file:
+
+```meson
+g_ir_compiler = find_program('g-ir-compiler')
+custom_target('foo typelib', command: [g_ir_compiler, '--output', '@OUTPUT@', '@INPUT@'],
+              input: foo_lib.vala_gir(),
+              output: 'Foo-1.0.typelib',
+              install: true,
+              install_dir: get_option('libdir') / 'girepository-1.0')
+```
+
+
+For older versions, calculating the path to the input is required, as is adding a
+manual dependency to the vala target:
+
 ```meson
 g_ir_compiler = find_program('g-ir-compiler')
 custom_target('foo typelib', command: [g_ir_compiler, '--output', '@OUTPUT@', '@INPUT@'],

docs/markdown/snippets/vala-target-extra-methods.md

@@ -1,14 +1,21 @@
 ## Vala BuildTarget dependency enhancements
 
 A BuildTarget that has Vala sources can now get a File dependency for its
-generated header and generated vapi.
+generated header, vapi, and gir files.
 
 ```meson
 lib = library('foo', 'foo.vala')
 lib_h = lib.vala_header()
 lib_s = static_lib('static', 'static.c', lib_h)
 
 lib_vapi = lib.vala_vapi()
+
+custom_target(
+  'foo-typelib',
+  command : ['g-ir-compiler', '--output', '@OUTPUT@', '@INPUT@'],
+  input : lib.vala_gir(),
+  output : 'Foo-1.0.typelib'
+)
 ```
 
 `static.c` will not start compilation until `lib.h` is generated.

docs/yaml/objects/build_tgt.yaml

@@ -93,3 +93,11 @@ methods:
     Returns a [[@file]] object pointing to a VAPI header generated by the vala
     compiler, if this target does not generate a VAPI file then it is an error
     to call this method.
+
+- name: vala_gir
+  returns: file
+  since: 1.10.0
+  description: |
+    Returns a [[@file]] object pointing to a GIR file generated by the vala
+    compiler, if this target does not generate a GIR file then it is an error
+    to call this method.

mesonbuild/interpreter/interpreterobjects.py

@@ -1012,6 +1012,18 @@ def vala_vapi_method(self, args: T.List[TYPE_var], kwargs: TYPE_kwargs) -> meson
         return mesonlib.File.from_built_file(
             self.interpreter.backend.get_target_dir(self._target_object), self._target_object.vala_vapi)
 
+    @FeatureNew('vala_gir', '1.10.0')
+    @noPosargs
+    @noKwargs
+    @InterpreterObject.method('vala_gir')
+    def vala_gir_method(self, args: T.List[TYPE_var], kwargs: TYPE_kwargs) -> mesonlib.File:
+        if not hasattr(self._target_object, 'vala_gir'):
+            raise mesonlib.MesonException("Attempted to get a Vala GIR from a target that doesn't generate one")
+
+        assert self.interpreter.backend is not None, 'for mypy'
+        return mesonlib.File.from_built_file(
+            self.interpreter.backend.get_target_dir(self._target_object), self._target_object.vala_gir)
+
 
 class ExecutableHolder(BuildTargetHolder[build.Executable]):
     pass

test cases/vala/9 gir/meson.build

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# Copyright © 2025 Intel Corporation
+
 project('foo', 'c', 'vala')
 
 glib = dependency('glib-2.0')
@@ -12,6 +15,6 @@ foo = shared_library('foo', 'foo.vala',
 
 custom_target('foo-typelib',
               command: [g_ir_compiler, '--output', '@OUTPUT@', '@INPUT@'],
-              input: meson.current_build_dir() + '/Foo-1.0.gir',
+              input: foo.vala_gir(),
               output: 'Foo-1.0.typelib',
-              depends: foo)
+              build_by_default : true)