8 files changed, 54 insertions, 17 deletions
diff --git a/solenv/gbuild/CppunitTest.mk b/solenv/gbuild/CppunitTest.mk
index 602dba107947..d90a2c89311c 100644
--- a/solenv/gbuild/CppunitTest.mk
+++ b/solenv/gbuild/CppunitTest.mk
@@ -480,5 +480,7 @@ gb_CppunitTest_set_warnings_not_errors = $(call gb_CppunitTest__forward_to_Linkt
 gb_CppunitTest_set_warnings_disabled = $(call gb_CppunitTest__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 gb_CppunitTest_set_external_code = $(call gb_CppunitTest__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 gb_CppunitTest_set_generated_cxx_suffix = $(call gb_CppunitTest__forward_to_Linktarget,$(0),$(1),$(2),$(3))
+gb_CppunitTest_use_clang = $(call gb_CppunitTest__forward_to_Linktarget,$(0),$(1),$(2),$(3))
+gb_CppunitTest_set_clang_precompiled_header = $(call gb_CppunitTest__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 
 # vim: set noet sw=4:
diff --git a/solenv/gbuild/Executable.mk b/solenv/gbuild/Executable.mk
index c782cd871856..66b44e156904 100644
--- a/solenv/gbuild/Executable.mk
+++ b/solenv/gbuild/Executable.mk
@@ -150,6 +150,8 @@ gb_Executable_set_warnings_not_errors = $(call gb_Executable__forward_to_Linktar
 gb_Executable_set_warnings_disabled = $(call gb_Executable__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 gb_Executable_set_external_code = $(call gb_Executable__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 gb_Executable_set_generated_cxx_suffix = $(call gb_Executable__forward_to_Linktarget,$(0),$(1),$(2),$(3))
+gb_Executable_use_clang = $(call gb_Executable__forward_to_Linktarget,$(0),$(1),$(2),$(3))
+gb_Executable_set_clang_precompiled_header = $(call gb_Executable__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 
 # Run-time use
 
diff --git a/solenv/gbuild/Library.mk b/solenv/gbuild/Library.mk
index 932ceefcd3cd..1973249f5db4 100644
--- a/solenv/gbuild/Library.mk
+++ b/solenv/gbuild/Library.mk
@@ -236,5 +236,7 @@ gb_Library_set_warnings_not_errors = $(call gb_Library__forward_to_Linktarget,$(
 gb_Library_set_warnings_disabled = $(call gb_Library__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 gb_Library_set_external_code = $(call gb_Library__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 gb_Library_set_generated_cxx_suffix = $(call gb_Library__forward_to_Linktarget,$(0),$(1),$(2),$(3))
+gb_Library_use_clang = $(call gb_Library__forward_to_Linktarget,$(0),$(1),$(2),$(3))
+gb_Library_set_clang_precompiled_header = $(call gb_Library__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 
 # vim: set noet sw=4:
diff --git a/solenv/gbuild/LinkTarget.mk b/solenv/gbuild/LinkTarget.mk
index 1702e881e1c0..0cb81a0a1daa 100644
--- a/solenv/gbuild/LinkTarget.mk
+++ b/solenv/gbuild/LinkTarget.mk
@@ -240,7 +240,7 @@ else
 $(call gb_CObject_get_target,%) : $(call gb_CObject_get_source,$(SRCDIR),%)
 	$(call gb_Output_announce,$*.c,$(true),$(if $(COMPILER_TEST),C? ,C  ),3)
 	$(call gb_Trace_StartRange,$*.c,$(if $(COMPILER_TEST),C? ,C  ))
-	$(call gb_CObject__command_pattern,$@,$(T_CFLAGS) $(T_CFLAGS_APPEND),$<,$(call gb_CObject_get_dep_target,$*),$(COMPILER_PLUGINS),$(T_SYMBOLS))
+	$(call gb_CObject__command_pattern,$@,$(T_CFLAGS) $(T_CFLAGS_APPEND),$<,$(call gb_CObject_get_dep_target,$*),$(COMPILER_PLUGINS),$(T_SYMBOLS),$(T_C))
 	$(call gb_Trace_EndRange,$*.c,$(if $(COMPILER_TEST),C? ,C  ))
 endif
 
@@ -303,7 +303,7 @@ $(call gb_CxxObject_get_target,%) : $(call gb_CxxObject_get_source,$(SRCDIR),%)
 	$(call gb_Output_announce,$*.cxx,$(true),$(if $(COMPILER_TEST),CPT,CXX),3)
 	$(call gb_Trace_StartRange,$*.cxx,$(if $(COMPILER_TEST),CPT,CXX))
 	$(eval $(gb_CxxObject__set_pchflags))
-	$(call gb_CObject__command_pattern,$@,$(T_CXXFLAGS) $(T_CXXFLAGS_APPEND) $(if $(COMPILER_TEST),$(gb_COMPILER_TEST_FLAGS)),$<,$(call gb_CxxObject_get_dep_target,$*),$(COMPILER_PLUGINS),$(T_SYMBOLS))
+	$(call gb_CObject__command_pattern,$@,$(T_CXXFLAGS) $(T_CXXFLAGS_APPEND) $(if $(COMPILER_TEST),$(gb_COMPILER_TEST_FLAGS)),$<,$(call gb_CxxObject_get_dep_target,$*),$(COMPILER_PLUGINS),$(T_SYMBOLS),$(T_CXX))
 	$(call gb_Trace_EndRange,$*.cxx,$(if $(COMPILER_TEST),CPT,CXX))
 endif
 
@@ -328,7 +328,7 @@ $(call gb_GenCObject_get_target,%) : $(gb_FORCE_COMPILE_ALL_TARGET)
 	$(call gb_Output_announce,$*.c,$(true),C  ,3)
 	$(call gb_Trace_StartRange,$*.c,C  )
 	test -f $(call gb_GenCObject_get_source,$*) || (echo "Missing generated source file $(call gb_GenCObject_get_source,$*)" && false)
-	$(call gb_CObject__command_pattern,$@,$(T_CFLAGS) $(T_CFLAGS_APPEND),$(call gb_GenCObject_get_source,$*),$(call gb_GenCObject_get_dep_target,$*),$(COMPILER_PLUGINS),$(T_SYMBOLS))
+	$(call gb_CObject__command_pattern,$@,$(T_CFLAGS) $(T_CFLAGS_APPEND),$(call gb_GenCObject_get_source,$*),$(call gb_GenCObject_get_dep_target,$*),$(COMPILER_PLUGINS),$(T_SYMBOLS),$(T_C))
 	$(call gb_Trace_EndRange,$*.c,C  )
 
 ifeq ($(gb_FULLDEPS),$(true))
@@ -353,7 +353,7 @@ $(call gb_GenCxxObject_get_target,%) : $(gb_FORCE_COMPILE_ALL_TARGET)
 	$(call gb_Trace_StartRange,$(subst $(BUILDDIR)/,,$(GEN_CXX_SOURCE)),CXX)
 	test -f $(GEN_CXX_SOURCE) || (echo "Missing generated source file $(GEN_CXX_SOURCE)" && false)
 	$(eval $(gb_CxxObject__set_pchflags))
-	$(call gb_CObject__command_pattern,$@,$(T_CXXFLAGS) $(T_CXXFLAGS_APPEND),$(GEN_CXX_SOURCE),$(call gb_GenCxxObject_get_dep_target,$*),$(COMPILER_PLUGINS),$(T_SYMBOLS))
+	$(call gb_CObject__command_pattern,$@,$(T_CXXFLAGS) $(T_CXXFLAGS_APPEND),$(GEN_CXX_SOURCE),$(call gb_GenCxxObject_get_dep_target,$*),$(COMPILER_PLUGINS),$(T_SYMBOLS),$(T_CXX))
 	$(call gb_Trace_EndRange,$(subst $(BUILDDIR)/,,$(GEN_CXX_SOURCE)),CXX)
 
 ifeq ($(gb_FULLDEPS),$(true))
@@ -836,6 +836,8 @@ $(call gb_LinkTarget_get_target,$(1)) : EXTERNAL_CODE :=
 $(call gb_LinkTarget_get_target,$(1)) : SOVERSIONSCRIPT :=
 $(call gb_LinkTarget_get_target,$(1)) : COMPILER_TEST :=
 $(call gb_LinkTarget_get_target,$(1)) : T_SYMBOLS := $(if $(call gb_LinkTarget__symbols_enabled,$(2)),$(true),$(false))
+$(call gb_LinkTarget_get_target,$(1)) : T_C :=
+$(call gb_LinkTarget_get_target,$(1)) : T_CXX :=
 
 ifeq ($(gb_FULLDEPS),$(true))
 ifeq (depcache:,$(filter depcache,$(.FEATURES)):$(gb_PARTIAL_BUILD))
@@ -1609,11 +1611,12 @@ $(call gb_LinkTarget_get_target,$(1)) : PCHOBJS = $$(PCHOBJEX)
 
 endef
 
-# call gb_LinkTarget_set_precompiled_header,linktarget,pchcxxfile,,linktargetmakefilename
+# 'compiler' set comes only from gb_LinkTarget_set_clang_precompiled_header
+# call gb_LinkTarget_set_precompiled_header,linktarget,pchcxxfile,,linktargetmakefilename,compiler
 define gb_LinkTarget_set_precompiled_header
 ifneq ($(gb_ENABLE_PCH),)
 $(call gb_LinkTarget__set_precompiled_header_impl,$(1),$(2),$(notdir $(2)),$(4))
-$(call gb_PrecompiledHeader_generate_rules,$(notdir $(2)),$(1),$(4),$(2))
+$(call gb_PrecompiledHeader_generate_rules,$(notdir $(2)),$(1),$(4),$(2),$(5))
 endif
 ifneq ($(gb_ENABLE_PCH)$(BLOCK_PCH),)
 $(call gb_LinkTarget__add_precompiled_header_object,$(1),$(2),$(notdir $(2)),$(4))
@@ -1621,6 +1624,14 @@ endif
 
 endef
 
+# It seems complicated to forward the clang setting to the PCH rules, so use an extra
+# function to set it manually. This variant should be used if gb_LinkTarget_use_clang is used.
+# call gb_LinkTarget_set_clang_precompiled_header,linktarget,pchcxxfile,,linktargetmakefilename
+define gb_LinkTarget_set_clang_precompiled_header
+$(call gb_LinkTarget_set_precompiled_header,$(1),$(2),$(3),$(4),$(CLANG_CXX))
+
+endef
+
 # call gb_LinkTarget__reuse_precompiled_header_impl,linktarget,pchcxxfile,pchtarget,linktargetmakefilename
 # Use the PCH as if it was LinkTarget's own, but do nothing with the PCH itself, just depend on it.
 define gb_LinkTarget__reuse_precompiled_header_impl
@@ -1773,4 +1784,13 @@ gb_LinkTarget_CXX_SUFFIX_$(call gb_LinkTarget__get_workdir_linktargetname,$(1))
 
 endef
 
+# C/C++ files will be build with Clang (if possible) instead of the default compiler.
+# call gb_LinkTarget_use_clang,linktarget,,linktargetmakefilename
+define gb_LinkTarget_use_clang
+$(call gb_LinkTarget_get_target,$(1)) : T_C := $(CLANG_C)
+$(call gb_LinkTarget_get_target,$(1)) : T_CXX := $(CLANG_CXX)
+
+endef
+
+
 # vim: set noet sw=4:
diff --git a/solenv/gbuild/PrecompiledHeaders.mk b/solenv/gbuild/PrecompiledHeaders.mk
index 55dcb332312d..0a07d6588436 100644
--- a/solenv/gbuild/PrecompiledHeaders.mk
+++ b/solenv/gbuild/PrecompiledHeaders.mk
@@ -36,7 +36,7 @@ ifneq ($(gb_ENABLE_PCH),)
 # for $(1)'s and things that are constant.
 # The defines are needed to get the right version of gb_PrecompiledHeader__get_debugdir.
 
-# $(call gb_PrecompiledHeader_generate_rules,pchtarget,linktarget,linktargetmakefilename,pchcxxfile)
+# $(call gb_PrecompiledHeader_generate_rules,pchtarget,linktarget,linktargetmakefilename,pchcxxfile,compiler)
 define gb_PrecompiledHeader_generate_rules
 
 $(call gb_PrecompiledHeader_get_dep_target,$(1),$(3)) :
@@ -50,7 +50,7 @@ $(call gb_PrecompiledHeader_get_target,$(1),$(3)) :
 	test "$$(PCH_LINKTARGETMAKEFILENAME)" = "$(3)" \
 		 || ( echo "Error, PCH $(1) built by $$(PCH_LINKTARGETMAKEFILENAME) instead of $(3)" >&2; exit 1)
 	rm -f $$@
-	$$(call gb_PrecompiledHeader__command,$$@,$(1),$$<,$$(PCH_DEFS),$$(PCH_CXXFLAGS) $$(gb_PrecompiledHeader_EXCEPTIONFLAGS),$$(INCLUDE),$(3))
+	$$(call gb_PrecompiledHeader__command,$$@,$(1),$$<,$$(PCH_DEFS),$$(PCH_CXXFLAGS) $$(gb_PrecompiledHeader_EXCEPTIONFLAGS),$$(INCLUDE),$(3),$(5))
 	$$(call gb_PrecompiledHeader__sum_command,$$@,$(1),$$<,$$(PCH_DEFS),$$(PCH_CXXFLAGS) $$(gb_PrecompiledHeader_EXCEPTIONFLAGS),$$(INCLUDE),$(3))
 	echo $$(sort $$(PCH_DEFS) $$(PCH_CXXFLAGS) $$(gb_PrecompiledHeader_EXCEPTIONFLAGS)) > $$(call gb_PrecompiledHeader_get_target,$(1),$(3)).flags
 ifeq ($(gb_FULLDEPS),$(true))
diff --git a/solenv/gbuild/StaticLibrary.mk b/solenv/gbuild/StaticLibrary.mk
index 0b372043e375..ca11815b6d49 100644
--- a/solenv/gbuild/StaticLibrary.mk
+++ b/solenv/gbuild/StaticLibrary.mk
@@ -120,5 +120,7 @@ gb_StaticLibrary_set_warnings_not_errors = $(call gb_StaticLibrary__forward_to_L
 gb_StaticLibrary_set_warnings_disabled = $(call gb_StaticLibrary__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 gb_StaticLibrary_set_external_code = $(call gb_StaticLibrary__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 gb_StaticLibrary_set_generated_cxx_suffix = $(call gb_StaticLibrary__forward_to_Linktarget,$(0),$(1),$(2),$(3))
+gb_StaticLibrary_use_clang = $(call gb_StaticLibrary__forward_to_Linktarget,$(0),$(1),$(2),$(3))
+gb_StaticLibrary_set_clang_precompiled_header = $(call gb_StaticLibrary__forward_to_Linktarget,$(0),$(1),$(2),$(3))
 
 # vim: set noet sw=4:
diff --git a/solenv/gbuild/platform/com_GCC_class.mk b/solenv/gbuild/platform/com_GCC_class.mk
index 29de22fe8634..f7e553dd5dc8 100644
--- a/solenv/gbuild/platform/com_GCC_class.mk
+++ b/solenv/gbuild/platform/com_GCC_class.mk
@@ -52,13 +52,20 @@ endef
 
 # CObject class
 
-# $(call gb_CObject__command_pattern,object,flags,source,dep-file,compiler-plugins,symbols)
+# $(call gb_CObject__compiler,source,compiler)
+define gb_CObject__compiler
+	$(if $(filter %.c %.m,$(1)), \
+		$(if $(2), $(2), $(gb_CC)), \
+		$(if $(2), $(2), $(gb_CXX)))
+endef
+
+# $(call gb_CObject__command_pattern,object,flags,source,dep-file,compiler-plugins,symbols,compiler)
 define gb_CObject__command_pattern
 $(call gb_Helper_abbreviate_dirs,\
 	mkdir -p $(dir $(1)) $(dir $(4)) && cd $(SRCDIR) && \
 	$(gb_COMPILER_SETUP) \
 	$(if $(5),$(gb_COMPILER_PLUGINS_SETUP)) \
-	$(if $(filter %.c %.m,$(3)), $(gb_CC), $(gb_CXX)) \
+	$(call gb_CObject__compiler,$(3),$(7)) \
 		$(DEFS) \
 		$(gb_LTOFLAGS) \
 		$(if $(VISIBILITY),,$(gb_VISIBILITY_FLAGS)) \
@@ -116,7 +123,7 @@ $(call gb_Helper_abbreviate_dirs,\
 	mkdir -p $(dir $(1)) $(dir $(call gb_PrecompiledHeader_get_dep_target,$(2),$(7))) && \
 	cd $(BUILDDIR)/ && \
 	CCACHE_DISABLE=1 $(gb_COMPILER_SETUP) \
-	$(gb_CXX) \
+	$(if $(8),$(8),$(gb_CXX)) \
 		-x c++-header \
 		$(4) $(5) \
 		$(if $(WARNINGS_DISABLED),$(gb_CXXFLAGS_DISABLE_WARNINGS)) \
diff --git a/solenv/gbuild/platform/com_MSC_class.mk b/solenv/gbuild/platform/com_MSC_class.mk
index f72c2a55f16b..848cb96397e3 100644
--- a/solenv/gbuild/platform/com_MSC_class.mk
+++ b/solenv/gbuild/platform/com_MSC_class.mk
@@ -34,13 +34,15 @@ endef
 
 # CObject class
 
-# $(call gb_CObject__compiler,flags,source)
+# $(call gb_CObject__compiler,flags,source,compiler)
 define gb_CObject__compiler
 	$(if $(filter YES,$(LIBRARY_X64)), $(CXX_X64_BINARY), \
 		$(if $(filter YES,$(PE_X86)), $(CXX_X86_BINARY), \
-			$(if $(filter %.c,$(2)), $(gb_CC), \
+			$(if $(filter %.c,$(2)), \
+				$(if $(3), $(3), $(gb_CC)), \
 				$(if $(filter -clr,$(1)), \
-					$(MSVC_CXX) -I$(SRCDIR)/solenv/clang-cl,$(gb_CXX)))))
+					$(MSVC_CXX) -I$(SRCDIR)/solenv/clang-cl,
+						$(if $(3), $(3), $(gb_CXX))))))
 endef
 
 # Avoid annoying warning D9025 about overriding command-line arguments.
@@ -50,12 +52,12 @@ gb_Helper_remove_overridden_flags = \
     $(lastword $(filter -Od -O2,$(1))) \
     $(lastword $(filter -arch:SSE -arch:SSE2 -arch:AVX -arch:AVX2,$(1)))
 
-# $(call gb_CObject__command_pattern,object,flags,source,dep-file,compiler-plugins,symbols)
+# $(call gb_CObject__command_pattern,object,flags,source,dep-file,compiler-plugins,symbols,compiler)
 define gb_CObject__command_pattern
 $(call gb_Helper_abbreviate_dirs,\
 	mkdir -p $(dir $(1)) $(dir $(4)) && \
 	unset INCLUDE && \
-	$(filter-out -arch:SSE,$(call gb_CObject__compiler,$(2),$(3))) \
+	$(filter-out -arch:SSE,$(call gb_CObject__compiler,$(2),$(3),$(7))) \
 		$(DEFS) \
 		$(gb_LTOFLAGS) \
 		$(call gb_Helper_remove_overridden_flags,$(filter -arch:SSE,$(call gb_CObject__compiler,$(2),$(3))) \
@@ -96,7 +98,7 @@ $(call gb_Output_announce,$(2),$(true),PCH,1)
 $(call gb_Helper_abbreviate_dirs,\
 	mkdir -p $(dir $(1)) $(dir $(call gb_PrecompiledHeader_get_dep_target,$(2),$(7))) && \
 	unset INCLUDE && \
-	$(filter-out -arch:SSE,$(call gb_CObject__compiler,$(4) $(5),$(3))) \
+	$(filter-out -arch:SSE,$(call gb_CObject__compiler,$(4) $(5),$(3),$(8))) \
 		$(call gb_Helper_remove_overridden_flags,$(filter -arch:SSE,$(call gb_CObject__compiler,$(4) $(5),$(3))) \
 			$(4) $(5) $(if $(WARNINGS_DISABLED),$(gb_CXXFLAGS_DISABLE_WARNINGS))) \
 		-Fd$(PDBFILE) \