Add C++ macro query variable

Author: virtuald

src/semiwrap/cmd_genmeson.py

@@ -18,6 +18,7 @@
     BuildTargetOutput,
     ExtensionModule,
     LocalDependency,
+    CppMacroValue,
     makeplan,
 )
 from .util import maybe_write_file, relpath_walk_up
@@ -47,7 +48,9 @@ def _make_string(s: str):
     return f"'{s}'"
 
 
-VarTypes = T.Union[InputFile, OutputFile, BuildTarget, ExtensionModule, LocalDependency]
+VarTypes = T.Union[
+    InputFile, OutputFile, BuildTarget, ExtensionModule, LocalDependency, CppMacroValue
+]
 
 
 class VarCache:
@@ -80,6 +83,9 @@ def getvar(self, item: VarTypes) -> str:
             elif isinstance(item, LocalDependency):
                 name = item.name.replace("-", "_")
                 var = f"{name}_dep"
+            elif isinstance(item, CppMacroValue):
+                name = item.name
+                var = f"_sw_cpp_var_{name}"
             else:
                 assert False
 
@@ -118,6 +124,8 @@ def _render_build_target(r: RenderBuffer, vc: VarCache, bt: BuildTarget):
         elif isinstance(arg, ExtensionModule):
             cmd.append(f"'@INPUT{len(tinput)}@'")
             tinput.append(vc.getvar(arg))
+        elif isinstance(arg, CppMacroValue):
+            cmd.append(vc.getvar(arg))
         else:
             assert False, f"unexpected {arg!r} in {bt}"
 
@@ -295,6 +303,8 @@ def gen_meson(
     #     is simpler to generate
 
     plan = makeplan(pathlib.Path(project_root))
+    macros: T.List[CppMacroValue] = []
+    build_targets: T.List[BuildTarget] = []
     modules: T.List[ExtensionModule] = []
     pyi_targets: T.List[BuildTarget] = []
     local_deps: T.List[LocalDependency] = []
@@ -308,17 +318,30 @@ def gen_meson(
             elif item.command == "dat2trampoline":
                 trampoline_targets.append(item)
             else:
-                _render_build_target(r0, vc, item)
+                build_targets.append(item)
         elif isinstance(item, ExtensionModule):
             # defer these to the end
             modules.append(item)
         elif isinstance(item, Entrypoint):
             eps.append(item)
         elif isinstance(item, LocalDependency):
             local_deps.append(item)
+        elif isinstance(item, CppMacroValue):
+            macros.append(item)
         else:
             assert False
 
+    if macros:
+        for macro in macros:
+            macro_name = _make_string(macro.name)
+            r0.writeln(
+                f"{vc.getvar(macro)} = meson.get_compiler('cpp').get_define({macro_name})"
+            )
+        r0.writeln()
+
+    for target in build_targets:
+        _render_build_target(r0, vc, target)
+
     if local_deps:
         r0.writeln()
         r0.write_trim(

src/semiwrap/cmd_header2dat.py

@@ -103,6 +103,7 @@ def make_argparser() -> argparse.ArgumentParser:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument("-I", "--include-paths", action="append", default=[])
     parser.add_argument("-D", "--pp-defines", action="append", default=[])
+    parser.add_argument("--cpp")
     parser.add_argument("name")
     parser.add_argument("src_yml", type=pathlib.Path)
     parser.add_argument("src_h", type=pathlib.Path)
@@ -120,6 +121,9 @@ def main():
     with open(args.in_casters, "rb") as fp:
         casters = pickle.load(fp)
 
+    if args.cpp:
+        args.pp_defines.append(f"__cplusplus {args.cpp}")
+
     generate_wrapper(
         name=args.name,
         src_yml=args.src_yml,

src/semiwrap/makeplan.py

@@ -32,6 +32,15 @@ class Entrypoint:
     package: str
 
 
+@dataclasses.dataclass(frozen=True)
+class CppMacroValue:
+    """
+    Represents the value of a macro defined by the C++ compiler
+    """
+
+    name: str
+
+
 @dataclasses.dataclass(frozen=True)
 class LocalDependency:
     name: str
@@ -77,6 +86,7 @@ class BuildTarget:
             Depfile,
             BuildTarget,
             BuildTargetOutput,
+            CppMacroValue,
         ],
         ...,
     ]
@@ -149,6 +159,10 @@ def generate(self):
         for name, caster_cfg in projectcfg.export_type_casters.items():
             yield from self._process_export_type_caster(name, caster_cfg)
 
+        # This is needed elsewhere
+        self._cpp_macro = CppMacroValue("__cplusplus")
+        yield self._cpp_macro
+
         #
         # Generate extension modules
         #
@@ -516,8 +530,7 @@ def _process_headers(
             # https://github.com/pkgconf/pkgconf/issues/391
             header2dat_args += ["-I", sysconfig.get_path("include")]
 
-            # TODO
-            header2dat_args += ["-D", "__cplusplus 201703L"]
+            header2dat_args += ["--cpp", self._cpp_macro]
 
             header2dat_args.append(yml)
             header2dat_args.append(yml_input)