qmake: Stop using -isystem flag

This option changes the order of include paths, which can cause problems of various kinds. See https://bugs.debian.org/958479 for an example. The benefit of that option is minimal for what it was intended. Additional change added when cherry-picking: build the GTK platformtheme with -Wno-error=parentheses flag, to fix GCC errors with GTK < 3.23. Change-Id: I80eeabd09764df290b60bc59aeb2f90d07723608 Reviewed-by: Thiago Macieira <[email protected]> (cherry picked from commit f133b22)
jbt-iot · Jun 25, 2020 · a5dd0b4 · a5dd0b4
1 parent 6afc56e
commit a5dd0b4
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Showing 6 changed files with 5 additions and 17 deletions.
diff --git a/mkspecs/common/clang.conf b/mkspecs/common/clang.conf
@@ -18,7 +18,6 @@ QMAKE_PCH_OUTPUT_EXT    = .pch
 
 QMAKE_CFLAGS_OPTIMIZE_SIZE = -Oz
 
-QMAKE_CFLAGS_ISYSTEM             = -isystem
 QMAKE_CFLAGS_PRECOMPILE          = -x c-header -c ${QMAKE_PCH_INPUT} -o ${QMAKE_PCH_OUTPUT}
 QMAKE_CFLAGS_USE_PRECOMPILE      = -Xclang -include-pch -Xclang ${QMAKE_PCH_OUTPUT}
 QMAKE_CFLAGS_LTCG                = -flto=thin

diff --git a/mkspecs/common/gcc-base.conf b/mkspecs/common/gcc-base.conf
@@ -46,7 +46,6 @@ QMAKE_CFLAGS_DEBUG         += -g
 QMAKE_CFLAGS_SHLIB         += $$QMAKE_CFLAGS_PIC
 QMAKE_CFLAGS_STATIC_LIB    += $$QMAKE_CFLAGS_PIC
 QMAKE_CFLAGS_APP           += $$QMAKE_CFLAGS_PIC
-QMAKE_CFLAGS_ISYSTEM        = -isystem
 QMAKE_CFLAGS_YACC          += -Wno-unused -Wno-parentheses
 QMAKE_CFLAGS_HIDESYMS      += -fvisibility=hidden
 QMAKE_CFLAGS_EXCEPTIONS_OFF += -fno-exceptions

diff --git a/mkspecs/linux-icc/qmake.conf b/mkspecs/linux-icc/qmake.conf
@@ -9,7 +9,6 @@ include(../common/icc-base-unix.conf)
 # modifications to icc-base-unix.conf
 
 QMAKE_CFLAGS_YACC       =
-QMAKE_CFLAGS_ISYSTEM    = -isystem
 QMAKE_CFLAGS_THREAD     = -D_REENTRANT
 
 QMAKE_CXXFLAGS_YACC     = $$QMAKE_CFLAGS_YACC

diff --git a/qmake/generators/unix/unixmake2.cpp b/qmake/generators/unix/unixmake2.cpp
@@ -198,18 +198,13 @@ UnixMakefileGenerator::writeMakeParts(QTextStream &t)
     t << "CXXFLAGS      = " << var("QMAKE_CXXFLAGS") << " $(DEFINES)\n";
     t << "INCPATH       =";
     {
-        QString isystem = var("QMAKE_CFLAGS_ISYSTEM");
         const ProStringList &incs = project->values("INCLUDEPATH");
         for(int i = 0; i < incs.size(); ++i) {
             const ProString &inc = incs.at(i);
             if (inc.isEmpty())
                 continue;
 
-            if (!isystem.isEmpty() && isSystemInclude(inc.toQString()))
-                t << ' ' << isystem << ' ';
-            else
-                t << " -I";
-            t << escapeFilePath(inc);
+            t << " -I" << escapeFilePath(inc);
         }
     }
     if(!project->isEmpty("QMAKE_FRAMEWORKPATH_FLAGS"))
@@ -1393,8 +1388,7 @@ void UnixMakefileGenerator::init2()
     }
 
     if (include_deps && project->isActiveConfig("gcc_MD_depends")) {
-        // use -MMD if we know about -isystem too
-        ProString MD_flag(project->values("QMAKE_CFLAGS_ISYSTEM").isEmpty() ? "-MD" : "-MMD");
+        ProString MD_flag("-MD");
         project->values("QMAKE_CFLAGS") += MD_flag;
         project->values("QMAKE_CXXFLAGS") += MD_flag;
     }

diff --git a/qmake/generators/win32/mingw_make.cpp b/qmake/generators/win32/mingw_make.cpp
@@ -200,17 +200,12 @@ void MingwMakefileGenerator::writeIncPart(QTextStream &t)
 {
     t << "INCPATH       = ";
 
-    QString isystem = var("QMAKE_CFLAGS_ISYSTEM");
     const ProStringList &incs = project->values("INCLUDEPATH");
     for (ProStringList::ConstIterator incit = incs.begin(); incit != incs.end(); ++incit) {
         QString inc = (*incit).toQString();
         inc.replace(QRegExp("\\\\$"), "");
 
-        if (!isystem.isEmpty() && isSystemInclude(inc))
-            t << isystem << ' ';
-        else
-            t << "-I";
-        t << escapeFilePath(inc) << ' ';
+        t << "-I" << escapeFilePath(inc) << ' ';
     }
     t << Qt::endl;
 }

diff --git a/src/plugins/platformthemes/gtk3/gtk3.pro b/src/plugins/platformthemes/gtk3/gtk3.pro
@@ -10,6 +10,8 @@ QT += core-private gui-private theme_support-private
 CONFIG += X11
 QMAKE_USE += gtk3
 DEFINES += GDK_VERSION_MIN_REQUIRED=GDK_VERSION_3_6
+# Needed for GTK < 3.23
+QMAKE_CXXFLAGS_WARN_ON += -Wno-error=parentheses
 
 HEADERS += \
         qgtk3dialoghelpers.h \