modules/rust: allow customizing env vars on bindgen

docs/markdown/Rust-module.md

@@ -67,6 +67,7 @@ It takes the following keyword arguments
 - `dependencies`: a list of `Dependency` objects to pass to the underlying clang call (*since 1.0.0*)
 - `language`: A literal string value of `c` or `cpp`. When set this will force bindgen to treat a source as the given language. Defaults to checking based on the input file extension. *(since 1.4.0)*
 - `bindgen_version`: a list of string version values. When set the found bindgen binary must conform to these constraints. *(since 1.4.0)*
+- `env`: environment variables to set, such as {'NAME1': 'value1', 'NAME2': 'value2'} or ['NAME1=value1', 'NAME2=value2'], or an env object which allows more sophisticated environment juggling. *(since 1.6.0)*
 
 ```meson
 rust = import('unstable-rust')

docs/markdown/snippets/bindgen_allows_setting_environment_variables.md

@@ -0,0 +1,7 @@
+## Bindgen now allows customizing environment variables
+
+Bindgen is configurable through environment variables on how it searches for
+clang and what extra arguments it passes to the compiler. The bindgen() function
+of the rust module now accepts an `env` keyword argument for customizing
+environment variables. The type of the argument is the same as `env` of
+[[custom_target]].

mesonbuild/modules/rust.py

@@ -14,11 +14,13 @@
                      CustomTarget, InvalidArguments, Jar, StructuredSources, SharedLibrary)
 from ..compilers.compilers import are_asserts_disabled, lang_suffixes
 from ..interpreter.type_checking import (
-    DEPENDENCIES_KW, LINK_WITH_KW, SHARED_LIB_KWS, TEST_KWS, OUTPUT_KW,
+    DEPENDENCIES_KW, LINK_WITH_KW, SHARED_LIB_KWS, TEST_KWS, OUTPUT_KW, ENV_KW,
     INCLUDE_DIRECTORIES, SOURCES_VARARGS, NoneType, in_set_validator
 )
 from ..interpreterbase import ContainerTypeInfo, InterpreterException, KwargInfo, typed_kwargs, typed_pos_args, noPosargs, permittedKwargs
-from ..mesonlib import File
+from ..mesonlib import (
+    File, EnvironmentVariables,
+)
 from ..programs import ExternalProgram
 
 if T.TYPE_CHECKING:
@@ -49,6 +51,7 @@ class FuncBindgen(TypedDict):
         output: str
         output_inline_wrapper: str
         dependencies: T.List[T.Union[Dependency, ExternalLibrary]]
+        env: T.Optional[EnvironmentVariables]
         language: T.Optional[Literal['c', 'cpp']]
         bindgen_version: T.List[str]
 
@@ -198,6 +201,7 @@ def test(self, state: ModuleState, args: T.Tuple[str, BuildTarget], kwargs: Func
         KwargInfo('bindgen_version', ContainerTypeInfo(list, str), default=[], listify=True, since='1.4.0'),
         INCLUDE_DIRECTORIES.evolve(since_values={ContainerTypeInfo(list, str): '1.0.0'}),
         OUTPUT_KW,
+        ENV_KW.evolve(since='1.6.0'),
         KwargInfo(
             'output_inline_wrapper',
             str,
@@ -330,6 +334,7 @@ def bindgen(self, state: ModuleState, args: T.List, kwargs: FuncBindgen) -> Modu
             extra_depends=depends,
             depend_files=depend_files,
             backend=state.backend,
+            env=kwargs['env'],
             description='Generating bindings for Rust {}',
         )
 

test cases/rust/12 bindgen/env/header.h

@@ -0,0 +1,9 @@
+// SPDX-license-identifer: Apache-2.0
+
+# pragma once
+
+#include "other.h"
+
+#ifdef EXPOSE_API
+int32_t add(const int32_t, const int32_t);
+#endif

test cases/rust/12 bindgen/env/meson.build

@@ -0,0 +1,22 @@
+# SPDX-license-identifer: Apache-2.0
+
+gen_env = rust.bindgen(
+  input : 'header.h',
+  output : 'header.rs',
+  env : {'BINDGEN_EXTRA_CLANG_ARGS' : '-DEXPOSE_API'},
+  include_directories : inc,
+)
+
+f_env = configure_file(
+  input : '../src/main.rs',
+  output : 'main.rs',
+  copy : true,
+)
+
+rust_bin_env = executable(
+  'rust_bin_env',
+  [f_env, gen_env],
+  link_with : c_lib,
+)
+
+test('generate with custom environment variables', rust_bin_env)

test cases/rust/12 bindgen/meson.build

@@ -129,6 +129,7 @@ endif
 
 subdir('sub')
 subdir('dependencies')
+subdir('env')
 
 gp = rust.bindgen(
   input : 'src/global-project.h',