Factor out windows resource compiler determination

Factor out determination of the windows resource compiler as
_find_resource_compiler().  Cache the result, so the work is only done once.

mesonbuild/modules/windows.py

@@ -32,26 +32,14 @@ class WindowsModule(ExtensionModule):
                 return compilers[l]
         raise MesonException('Resource compilation requires a C or C++ compiler.')
 
-    @FeatureNewKwargs('windows.compile_resources', '0.47.0', ['depend_files', 'depends'])
-    @permittedKwargs({'args', 'include_directories', 'depend_files', 'depends'})
-    def compile_resources(self, state, args, kwargs):
-        comp = self.detect_compiler(state.compilers)
+    def _find_resource_compiler(self, state):
+        # FIXME: Does not handle `native: true` executables, see
+        # See https://github.com/mesonbuild/meson/issues/1531
 
-        extra_args = mesonlib.stringlistify(kwargs.get('args', []))
-        wrc_depend_files = extract_as_list(kwargs, 'depend_files', pop = True)
-        wrc_depends = extract_as_list(kwargs, 'depends', pop = True)
-        for d in wrc_depends:
-            if isinstance(d, CustomTargetHolder):
-                extra_args += get_include_args([d.outdir_include()])
-        inc_dirs = extract_as_list(kwargs, 'include_directories', pop = True)
-        for incd in inc_dirs:
-            if not isinstance(incd.held_object, (str, build.IncludeDirs)):
-                raise MesonException('Resource include dirs should be include_directories().')
-        extra_args += get_include_args(inc_dirs)
+        if hasattr(self, '_rescomp'):
+            return self._rescomp
 
         rescomp = None
-        # FIXME: Does not handle `native: true` executables, see
-        # https://github.com/mesonbuild/meson/issues/1531
         if state.environment.is_cross_build():
             # If cross compiling see if windres has been specified in the
             # cross file before trying to find it another way.
@@ -65,6 +53,7 @@ class WindowsModule(ExtensionModule):
                 rescomp = ExternalProgram('windres', command=os.environ.get('WINDRES'), silent=True)
 
         if not rescomp or not rescomp.found():
+            comp = self.detect_compiler(state.compilers)
             if comp.id == 'msvc':
                 rescomp = ExternalProgram('rc', silent=True)
             else:
@@ -73,6 +62,25 @@ class WindowsModule(ExtensionModule):
         if not rescomp.found():
             raise MesonException('Could not find Windows resource compiler')
 
+        self._rescomp = rescomp
+        return self._rescomp
+
+    @FeatureNewKwargs('windows.compile_resources', '0.47.0', ['depend_files', 'depends'])
+    @permittedKwargs({'args', 'include_directories', 'depend_files', 'depends'})
+    def compile_resources(self, state, args, kwargs):
+        extra_args = mesonlib.stringlistify(kwargs.get('args', []))
+        wrc_depend_files = extract_as_list(kwargs, 'depend_files', pop = True)
+        wrc_depends = extract_as_list(kwargs, 'depends', pop = True)
+        for d in wrc_depends:
+            if isinstance(d, CustomTargetHolder):
+                extra_args += get_include_args([d.outdir_include()])
+        inc_dirs = extract_as_list(kwargs, 'include_directories', pop = True)
+        for incd in inc_dirs:
+            if not isinstance(incd.held_object, (str, build.IncludeDirs)):
+                raise MesonException('Resource include dirs should be include_directories().')
+        extra_args += get_include_args(inc_dirs)
+
+        rescomp = self._find_resource_compiler(state)
         if 'rc' in rescomp.get_path():
             # RC is used to generate .res files, a special binary resource
             # format, which can be passed directly to LINK (apparently LINK uses