qmake: Suppress built-in suffixes for make

They cause make to run much slower, and qmake writes everything
explicitly, so they're not really needed.

Change-Id: Ia47674eec8309e120c8264b7b6687677a520d5b9
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Jörg Bornemann <joerg.bornemann@qt.io>

4 files changed, 15 insertions, 0 deletions

diff --git a/qmake/generators/makefile.cpp b/qmake/generators/makefile.cpp
index c9c45990f4..e16082e62c 100644
--- a/qmake/generators/makefile.cpp
+++ b/qmake/generators/makefile.cpp
@@ -2243,6 +2243,7 @@ MakefileGenerator::writeDummyMakefile(QTextStream &t)
       << "@echo \"Skipped.\"\n\n";
     writeMakeQmake(t);
     t << "FORCE:\n\n";
+    suppressBuiltinRules(t);
     return true;
 }
 
@@ -2257,6 +2258,7 @@ MakefileGenerator::writeMakefile(QTextStream &t)
     writeInstalls(t);
 
     t << "FORCE:\n\n";
+    suppressBuiltinRules(t);
     return true;
 }
 
@@ -2778,6 +2780,13 @@ MakefileGenerator::writeSubTargets(QTextStream &t, QList<MakefileGenerator::SubT
         writeInstalls(t, true);
     }
     t << "FORCE:\n\n";
+    suppressBuiltinRules(t);
+}
+
+void
+MakefileGenerator::suppressBuiltinRules(QTextStream &t) const
+{
+    t << ".SUFFIXES:\n\n";
 }
 
 void
diff --git a/qmake/generators/makefile.h b/qmake/generators/makefile.h
index 2927e2de56..1e3b6fc470 100644
--- a/qmake/generators/makefile.h
+++ b/qmake/generators/makefile.h
@@ -121,6 +121,7 @@ protected:
     void writeSubTargetCall(QTextStream &t,
             const QString &in_directory, const QString &in, const QString &out_directory, const QString &out,
             const QString &out_directory_cdin, const QString &makefilein);
+    virtual void suppressBuiltinRules(QTextStream &t) const;
     virtual void writeSubMakeCall(QTextStream &t, const QString &outDirectory_cdin,
                                   const QString &makeFileIn);
     virtual void writeSubTargets(QTextStream &t, QList<SubTarget*> subtargets, int flags);
diff --git a/qmake/generators/win32/msvc_nmake.cpp b/qmake/generators/win32/msvc_nmake.cpp
index 50666215c6..efba1f1e83 100644
--- a/qmake/generators/win32/msvc_nmake.cpp
+++ b/qmake/generators/win32/msvc_nmake.cpp
@@ -174,6 +174,10 @@ QString NmakeMakefileGenerator::var(const ProKey &value) const
     return MakefileGenerator::var(value);
 }
 
+void NmakeMakefileGenerator::suppressBuiltinRules(QTextStream &t) const
+{
+}
+
 void NmakeMakefileGenerator::init()
 {
     /* this should probably not be here, but I'm using it to wrap the .t files */
diff --git a/qmake/generators/win32/msvc_nmake.h b/qmake/generators/win32/msvc_nmake.h
index 3064f06521..23172c9230 100644
--- a/qmake/generators/win32/msvc_nmake.h
+++ b/qmake/generators/win32/msvc_nmake.h
@@ -52,6 +52,7 @@ protected:
     QString defaultInstall(const QString &t) override;
     QStringList &findDependencies(const QString &file) override;
     QString var(const ProKey &value) const override;
+    void suppressBuiltinRules(QTextStream &t) const override;
     QString precompH, precompObj, precompPch;
     QString precompObjC, precompPchC;
     bool usePCH = false;