Clang: Properly set up warnings for clang-based libraries

Add warning flags to QMAKE_CXXFLAGS_WARN_ON to have them
after default warnings.

Change-Id: Ic94fe36175d3198191251d5b475f8f8ed000bef7
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/plugins/clangformat/clangformat.pro

@@ -13,7 +13,8 @@ win32 {
 LIBS += $$CLANGFORMAT_LIBS
 INCLUDEPATH += $$LLVM_INCLUDEPATH
 
-QMAKE_CXXFLAGS += $$LLVM_CXXFLAGS
+QMAKE_CXXFLAGS_WARN_ON *= $$LLVM_CXXFLAGS_WARNINGS
+QMAKE_CXXFLAGS *= $$LLVM_CXXFLAGS
 unix:!macos:QMAKE_LFLAGS += -Wl,--exclude-libs,ALL
 
 SOURCES = \

src/plugins/clangformat/clangformat.qbs

@@ -17,6 +17,7 @@ QtcPlugin {
     condition: libclang.present
                && (!qbs.targetOS.contains("windows") || libclang.llvmBuildModeMatches)
 
+    cpp.cxxFlags: base.concat(libclang.llvmToolingCxxFlags)
     cpp.defines: base.concat("CLANGPCHMANAGER_LIB")
     cpp.includePaths: base.concat(libclang.llvmIncludeDir)
     cpp.libraryPaths: base.concat(libclang.llvmLibDir)

src/shared/clang/clang_installation.pri

@@ -111,6 +111,17 @@ defineReplace(splitFlags) {
     return($$result)
 }
 
+defineReplace(extractWarnings) {
+    flags = $$1
+    result =
+    for (flag, flags) {
+        contains(flag, ^[-/][wW].*$) {
+            result += $$flag
+        }
+    }
+    return($$result)
+}
+
 CLANGTOOLING_LIBS=-lclangTooling -lclangIndex -lclangFrontend -lclangParse -lclangSerialization \
                   -lclangSema -lclangEdit -lclangAnalysis -lclangDriver -lclangDynamicASTMatchers \
                   -lclangASTMatchers -lclangToolingCore -lclangAST -lclangLex -lclangBasic
@@ -241,6 +252,9 @@ isEmpty(LLVM_VERSION) {
 
     LLVM_CXXFLAGS = $$splitFlags($$LLVM_CXXFLAGS)
 
+    LLVM_CXXFLAGS_WARNINGS = $$extractWarnings($$LLVM_CXXFLAGS)
+    LLVM_CXXFLAGS -= $$LLVM_CXXFLAGS_WARNINGS
+
     LLVM_IS_COMPILED_WITH_RTTI = $$system($$llvm_config --has-rtti, lines)
 
     unix:!disable_external_rpath:!contains(QMAKE_DEFAULT_LIBDIRS, $${LLVM_LIBDIR}) {

src/tools/clangpchmanagerbackend/clangpchmanagerbackend.pro

@@ -18,7 +18,8 @@ QT -= gui
 LIBS += $$LIBTOOLING_LIBS
 INCLUDEPATH += $$LLVM_INCLUDEPATH
 
-QMAKE_CXXFLAGS += $$LLVM_CXXFLAGS
+QMAKE_CXXFLAGS_WARN_ON *= $$LLVM_CXXFLAGS_WARNINGS
+QMAKE_CXXFLAGS *= $$LLVM_CXXFLAGS
 
 INCLUDEPATH += ../clangrefactoringbackend/source
 

src/tools/clangrefactoringbackend/clangrefactoringbackend.pro

@@ -19,7 +19,8 @@ LIBS += $$LIBTOOLING_LIBS
 INCLUDEPATH += $$LLVM_INCLUDEPATH
 INCLUDEPATH += ../clangpchmanagerbackend/source
 
-QMAKE_CXXFLAGS += $$LLVM_CXXFLAGS
+QMAKE_CXXFLAGS_WARN_ON *= $$LLVM_CXXFLAGS_WARNINGS
+QMAKE_CXXFLAGS *= $$LLVM_CXXFLAGS
 
 SOURCES += \
     clangrefactoringbackendmain.cpp

tests/unit/unittest/clang_dependency.pri

@@ -22,6 +22,7 @@ include(../../../src/shared/clang/clang_defines.pri)
     !contains(QMAKE_DEFAULT_LIBDIRS, $$LLVM_LIBDIR): QMAKE_RPATHDIR += $$LLVM_LIBDIR
 
     LLVM_CXXFLAGS ~= s,-g\d?,
+    QMAKE_CXXFLAGS_WARN_ON *= $$LLVM_CXXFLAGS_WARNINGS
     QMAKE_CXXFLAGS *= $$LLVM_CXXFLAGS
 
     DEFINES += CLANG_COMPILER_PATH=\"R\\\"xxx($$LLVM_BINDIR/clang)xxx\\\"\"