Basic support for generating C++ header from Swift code

mesonbuild/compilers/swift.py

@@ -3,6 +3,7 @@
 
 from __future__ import annotations
 
+import json
 import re
 import subprocess, os.path
 import typing as T
@@ -29,6 +30,27 @@
     's': ['-O'],
 }
 
+
+def _get_swift_library_paths(exelist: T.List[str], info: MachineInfo, static: bool) -> T.List[str]:
+    try:
+        command = [*exelist, '-print-target-info']
+        if static:
+            command += ['-static-stdlib']
+        s = subprocess.check_output(command, universal_newlines=True,
+                                    encoding='utf-8', stderr=subprocess.STDOUT)
+        data = json.loads(s)
+        paths = [
+            *data['paths']['runtimeLibraryPaths'],
+            *data['paths']['runtimeLibraryImportPaths'],
+            *([data['paths']['sdkPath']] if info.is_darwin() else []),
+        ]
+        return paths
+    except subprocess.CalledProcessError as e:
+        raise MesonException(f'Failed to get Swift target info: {e.output}')
+    except KeyError:
+        raise MesonException('Failed to extract Swift library path')
+
+
 class SwiftCompiler(Compiler):
 
     LINKER_PREFIX = ['-Xlinker']
@@ -54,6 +76,9 @@ def __init__(self, exelist: T.List[str], version: str, for_machine: MachineChoic
                 mlog.error('xcrun not found. Install Xcode to compile Swift code.')
                 raise MesonException('Could not detect Xcode. Please install it to compile Swift code.')
 
+        self.dynamic_library_path: T.List[str] = _get_swift_library_paths(exelist, info, False)
+        self.static_library_path: T.List[str] = _get_swift_library_paths(exelist, info, True)
+
     def get_pic_args(self) -> T.List[str]:
         return []
 

mesonbuild/modules/swift.py

@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2025 The Meson development team
+
+from __future__ import annotations
+
+import typing as T
+
+from . import NewExtensionModule, ModuleInfo, ModuleReturnValue
+from mesonbuild import build
+from mesonbuild.compilers.swift import SwiftCompiler
+from mesonbuild.interpreterbase.decorators import typed_kwargs, typed_pos_args
+
+if T.TYPE_CHECKING:
+    from . import ModuleState
+    from mesonbuild.interpreter import Interpreter
+
+
+def initialize(*args: T.Any, **kwargs: T.Any) -> SwiftModule:
+    return SwiftModule(*args, **kwargs)
+
+
+class SwiftModule(NewExtensionModule):
+    INFO = ModuleInfo('swift', '1.7.99')
+
+    def __init__(self, interpreter: Interpreter):
+        super().__init__()
+        self.interpreter = interpreter
+        self.swiftc: T.Optional[SwiftCompiler]
+
+        try:
+            swiftc = interpreter.compilers.host['swift']
+            assert isinstance(swiftc, SwiftCompiler), 'swiftc is not an instance of SwiftCompiler'
+            self.swiftc = swiftc
+        except KeyError:
+            self.swiftc = None
+
+        self.methods.update({
+            'get_library_path': self.get_library_path,
+            'generate_cpp_header': self.generate_cpp_header,
+        })
+
+    @typed_pos_args('swift.get_library_path')
+    @typed_kwargs('swift.get_library_path')
+    def get_library_path(self, state: ModuleState, args, kwargs) -> ModuleReturnValue:
+        paths = [*self.swiftc.dynamic_library_path, *self.swiftc.static_library_path]
+        return ModuleReturnValue(paths, [])
+
+    @typed_pos_args('swift.generate_cpp_header', build.BuildTarget)
+    @typed_kwargs('swift.generate_cpp_header')
+    def generate_cpp_header(self, state: ModuleState, args: T.Tuple[build.BuildTarget], kwargs) -> ModuleReturnValue:
+        (module,) = args
+
+        header_name = f'{module.name}-Swift.h'
+        command = [
+            *self.swiftc.get_exelist(),
+            '@INPUT@',
+            *self.swiftc.get_module_args(module.name),
+            *self.swiftc.get_cxx_interoperability_args(self.interpreter.compilers.host),
+            '-emit-clang-header-path', '@OUTPUT@',
+        ]
+
+        tgt = build.CustomTarget(header_name, state.subdir, state.subproject, state.environment, command,
+                                 module.get_sources() + module.get_generated_sources(), [header_name],
+                                 backend=state.backend)
+
+        return ModuleReturnValue(tgt, [tgt])