use divided module

.clangd

@@ -1,5 +1,6 @@
 CompileFlags:
   Add:
+    - -std=c++26
     - -Xclang
     - -fno-validate-pch
     - -fretain-comments-from-system-headers

Makefile

@@ -1,24 +1,39 @@
 .RECIPEPREFIX = >
 .DEFAULT_GOAL = build/main.out
 CXX = clang++
-CXXFLAGS += -std=c++26 -Wno-experimental-header-units
+CXXFLAGS += -std=c++26 -Wno-experimental-header-units -Wno-unused-command-line-argument
 LDFLAGS += -std=c++26
 SYSTEMHEADER_FLAGS = -Wno-deprecated-builtins -Wno-pragma-system-header-outside-header -Wno-keyword-compat
-build_module_path = $(let first rest,$1,$(if $(rest),-fmodule-file=$(first) $(call build_module_path,$(rest)),-fmodule-file=$(first)))
+module_pair = $(if $(findstring user,$1),$(patsubst build/user/%.pcm,%=,$1))$1
+build_module_path = $(if $1,$(let first rest,$1,$(if $(rest),-fmodule-file=$(call module_pair,$(first)) $(call build_module_path,$(rest)),-fmodule-file=$(call module_pair,$(first)))))
+object_build = $(filter-out %.pcm,$^) $(call build_module_path,$(filter %.pcm,$^))
+autodir = @mkdir -p $(@D)
 
-build/main.out: build/main.o
+build/main.out: build/main.o build/builder.o
+> $(call autodir)
 > $(CXX) $(LDFLAGS) $^ -o $@
 
-build/main.o: main.cxx build/print.pcm build/type_traits.pcm
+build/main.o:: main.cxx build/system/print.pcm build/user/builder.pcm
-> $(CXX) $(CXXFLAGS) -c $(filter-out %.pcm,$^) $(call build_module_path,$(filter %.pcm,$^))
+
+build/builder.o:: builder.cppm build/system/type_traits.pcm
+build/user/builder.pcm:: build/system/type_traits.pcm
+
+build/%.o::
+> $(call autodir)
+> $(CXX) $(CXXFLAGS) -c $(call object_build)
 > @mv $(patsubst build/%,%,$@) $@
 
-build/%.pcm:
+build/user/%.pcm:: %.cppm
-> $(CXX) $(CXXFLAGS) -xc++-system-header --precompile $(patsubst build/%.pcm,%,$@) -o $@ $(SYSTEMHEADER_FLAGS)
+> $(call autodir)
+> $(CXX) $(CXXFLAGS) --precompile -o $@ $(call object_build)
+
+build/system/%.pcm:
+> $(call autodir)
+> $(CXX) $(CXXFLAGS) -xc++-system-header --precompile $(patsubst build/system/%.pcm,%,$@) -o $@ $(SYSTEMHEADER_FLAGS)
 
 .PHONY: clean run
 clean:
-> @-rm -rf ./build/*
+> @-rm -rf ./build
 bear: clean
 > bear -- $(MAKE)
 

builder.cppm

@@ -0,0 +1,56 @@
+export module builder;
+import <type_traits>;
+
+export template <bool param1 = false, bool param2 = false>
+struct Builder;
+template <bool enabled>
+struct BuildMixin {};
+
+template <>
+struct BuildMixin<true> {
+  auto build(this auto&& self)
+    requires requires { self.p1 + self.p2; }
+  {
+    return self.p1 + self.p2;
+  }
+};
+
+template <bool enabled>
+struct Param1Mixin {};
+
+template <>
+struct Param1Mixin<false> {
+  auto fill_param1(this auto&& self)
+    requires requires { self.p1; }
+  {
+    self.p1 = 1;
+    return Builder<true, std::remove_reference_t<decltype(self)>::param2_v>(
+        self);
+  }
+};
+
+template <bool enabled>
+struct Param2Mixin {};
+
+template <>
+struct Param2Mixin<false> {
+  auto fill_param2(this auto&& self)
+    requires requires { self.p2; }
+  {
+    self.p2 = 1;
+    return Builder<std::remove_reference_t<decltype(self)>::param1_v, true>(
+        self);
+  }
+};
+
+template <bool param1, bool param2>
+struct Builder : BuildMixin<param1 && param2>,
+                 Param1Mixin<param1>,
+                 Param2Mixin<param2> {
+  const constinit static auto param1_v = param1;
+  const constinit static auto param2_v = param2;
+  int p1;
+  int p2;
+  Builder() : p1(0), p2(0) {}
+  Builder(auto&& other) : p1(other.p1), p2(other.p2) {}
+};

main.cxx

@@ -1,59 +1,5 @@
 import <print>;
-import <type_traits>;
+import builder;
-
-template <bool param1 = false, bool param2 = false>
-struct Builder;
-template <bool enabled>
-struct BuildMixin {};
-
-template <>
-struct BuildMixin<true> {
-  auto build(this auto&& self)
-    requires requires { self.p1 + self.p2; }
-  {
-    return self.p1 + self.p2;
-  }
-};
-
-template <bool enabled>
-struct Param1Mixin {};
-
-template <>
-struct Param1Mixin<false> {
-  auto fill_param1(this auto&& self)
-    requires requires { self.p1; }
-  {
-    self.p1 = 1;
-    return Builder<true, std::remove_reference_t<decltype(self)>::param2_v>(
-        self);
-  }
-};
-
-template <bool enabled>
-struct Param2Mixin {};
-
-template <>
-struct Param2Mixin<false> {
-  auto fill_param2(this auto&& self)
-    requires requires { self.p2; }
-  {
-    self.p2 = 1;
-    return Builder<std::remove_reference_t<decltype(self)>::param1_v, true>(
-        self);
-  }
-};
-
-template <bool param1, bool param2>
-struct Builder : BuildMixin<param1 && param2>,
-                 Param1Mixin<param1>,
-                 Param2Mixin<param2> {
-  const constinit static auto param1_v = param1;
-  const constinit static auto param2_v = param2;
-  int p1;
-  int p2;
-  Builder() : p1(0), p2(0) {}
-  Builder(auto&& other) : p1(other.p1), p2(other.p2) {}
-};
 
 auto main() -> int {
   Builder builder;