test(build-mcpp): use the typed import mcpp; module (Clang CI coverage) (#60)

* test(build-mcpp): use the typed import mcpp; build module (Clang CI coverage)

Converts the build-mcpp member's build.mcpp to import mcpp; (modules-first;
textual #include only for file I/O). On macOS/Windows the workspace job runs this
under clang, exercising the import-mcpp Clang module path. Needs mcpp >= 0.0.81.
(held until 0.0.81 is released)

* ci: bump mcpp 0.0.79 -> 0.0.81 (typed import mcpp; for build-mcpp member)

Author: Sunrisepeak

.github/workflows/validate.yml

@@ -13,7 +13,7 @@ on:
 env:
   # Bumped to 0.0.78: carries L3 build.mcpp native build program (build-mcpp member),
   # compat.openblas Windows recipe (bin/libopenblas.dll staged beside the .exe).
-  MCPP_VERSION: "0.0.79"
+  MCPP_VERSION: "0.0.81"
 
 jobs:
   lint:
@@ -111,20 +111,20 @@ jobs:
         include:
           - platform: linux
             os: ubuntu-latest
-            archive: mcpp-0.0.79-linux-x86_64.tar.gz
-            root: mcpp-0.0.79-linux-x86_64
+            archive: mcpp-0.0.81-linux-x86_64.tar.gz
+            root: mcpp-0.0.81-linux-x86_64
             mcpp: bin/mcpp
             xlings: registry/bin/xlings
           - platform: macos
             os: macos-15
-            archive: mcpp-0.0.79-macosx-arm64.tar.gz
-            root: mcpp-0.0.79-macosx-arm64
+            archive: mcpp-0.0.81-macosx-arm64.tar.gz
+            root: mcpp-0.0.81-macosx-arm64
             mcpp: bin/mcpp
             xlings: registry/bin/xlings
           - platform: windows
             os: windows-latest
-            archive: mcpp-0.0.79-windows-x86_64.zip
-            root: mcpp-0.0.79-windows-x86_64
+            archive: mcpp-0.0.81-windows-x86_64.zip
+            root: mcpp-0.0.81-windows-x86_64
             mcpp: bin/mcpp.exe
             xlings: registry/bin/xlings.exe
     steps:

tests/examples/build-mcpp/build.mcpp

@@ -1,13 +1,13 @@
-// Native build program: generate a source the test links + define a macro the
-// test sees. mcpp compiles+runs this (cwd = project root) before the build.
+// Modules-first build program: import mcpp; for the typed directive API. A textual
+// #include is still fine for file I/O (only `import std;` is unnecessary).
 #include <filesystem>
 #include <fstream>
-#include <cstdio>
+import mcpp;
 int main() {
     std::filesystem::create_directories("src");
     std::ofstream("src/generated.cpp") << "int answer() { return 42; }\n";
-    std::puts("mcpp:generated=src/generated.cpp");
-    std::puts("mcpp:cxxflag=-DBUILT_BY_BUILD_MCPP=1");
-    std::puts("mcpp:rerun-if-changed=build.mcpp");
+    mcpp::generated("src/generated.cpp");
+    mcpp::define("BUILT_BY_BUILD_MCPP");   // cfg= → -DBUILT_BY_BUILD_MCPP
+    mcpp::rerun_if_changed("build.mcpp");
     return 0;
 }