[Libreoffice-commits] core.git: compilerplugins/Makefile-clang.mk config_host.mk.in configure.ac

[Stephan Bergmann (via logerrit)]

 compilerplugins/Makefile-clang.mk |    8 ++++++++
 config_host.mk.in                 |    1 +
 configure.ac                      |   14 ++++++++++++++
 3 files changed, 23 insertions(+)

New commits:
commit bce14e97a6dad7686643d094995433c77e4aee7e
Author:     Stephan Bergmann <sbergman at redhat.com>
AuthorDate: Fri Feb 14 16:28:53 2020 +0100
Commit:     Stephan Bergmann <sbergman at redhat.com>
CommitDate: Fri Feb 14 19:24:32 2020 +0100

    Prevent -Werror,-Wunknown-warning-option when building compilerplugins
    
    ...with --enable-werror (seen it fail with a local build against a locally
    built Clang 5.0.2).
    
    (bin/gen-boost-headers faces a similar dilemma with Clang needing to silence
    -Wunknown-warning-option and GCC failing upon the silencing incantation.  There,
    we were able to hack around that with a preceding
    
      #pragma GCC diagnostic ignored "-Wpragmas"
    
    Here, the easiest approach appears to be a new COMPILER_PLUGINS_COM_IS_CLANG
    analoguous to the existing COM_IS_CLANG.)
    
    Change-Id: I9036261fdd238c8a020a1d88b4e75fd444f9e030
    Reviewed-on: https://gerrit.libreoffice.org/c/core/+/88725
    Tested-by: Jenkins
    Reviewed-by: Stephan Bergmann <sbergman at redhat.com>

diff --git a/compilerplugins/Makefile-clang.mk b/compilerplugins/Makefile-clang.mk
index 543ec27aad44..266919cf02b8 100644
--- a/compilerplugins/Makefile-clang.mk
+++ b/compilerplugins/Makefile-clang.mk
@@ -101,6 +101,14 @@ CLANGWERROR :=
 #TODO: /WX
 else
 CLANGWERROR := -Werror
+# When COMPILER_PLUGINS_CXXFLAGS (obtained via `llvm-config --cxxflags`) contains options like
+# -Wno-maybe-uninitialized that are targeting GCC (when LLVM was actually built with GCC), and
+# COMPILER_PLUGINS_CXX (defaulting to CXX) deonotes a Clang that does not understand those options,
+# it fails with -Werror,-Wunknown-warning-option, so we need -Wno-unknown-warning-option (but which
+# GCC does not understand) at least with -Werror:
+ifeq ($(COMPILER_PLUGINS_COM_IS_CLANG),TRUE)
+CLANGWERROR += -Wno-unknown-warning-option
+endif
 endif
 endif
 
diff --git a/config_host.mk.in b/config_host.mk.in
index 9dd4b72c421c..ef612734da3c 100644
--- a/config_host.mk.in
+++ b/config_host.mk.in
@@ -78,6 +78,7 @@ export COMMONS_LOGGING_JAR=@COMMONS_LOGGING_JAR@
 export COMMONS_LOGGING_VERSION=@COMMONS_LOGGING_VERSION@
 export COMPATH=@COMPATH@
 export COMPILER_PLUGINS=@COMPILER_PLUGINS@
+export COMPILER_PLUGINS_COM_IS_CLANG=@COMPILER_PLUGINS_COM_IS_CLANG@
 export COMPILER_PLUGINS_CXX=@COMPILER_PLUGINS_CXX@
 export COMPILER_PLUGINS_CXXFLAGS=@COMPILER_PLUGINS_CXXFLAGS@
 export COMPILER_PLUGINS_CXX_LINKFLAGS=@COMPILER_PLUGINS_CXX_LINKFLAGS@
diff --git a/configure.ac b/configure.ac
index 3fa8fc760e3f..e186f6d3eb73 100644
--- a/configure.ac
+++ b/configure.ac
@@ -7218,6 +7218,7 @@ if test "$COM_IS_CLANG" != "TRUE"; then
     fi
 fi
 
+COMPILER_PLUGINS_COM_IS_CLANG=
 if test "$COM_IS_CLANG" = "TRUE"; then
     if test -n "$enable_compiler_plugins"; then
         compiler_plugins="$enable_compiler_plugins"
@@ -7336,6 +7337,18 @@ if test "$COM_IS_CLANG" = "TRUE"; then
         LDFLAGS=$save_LDFLAGS
         LIBS="$save_LIBS"
         AC_LANG_POP([C++])
+
+        AC_MSG_CHECKING([whether the compiler for building compilerplugins is actually Clang])
+        AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+            #ifndef __clang__
+            you lose
+            #endif
+            int foo=42;
+            ]])],
+            [AC_MSG_RESULT([yes])
+             COMPILER_PLUGINS_COM_IS_CLANG=TRUE],
+            [AC_MSG_RESULT([no])])
+        AC_SUBST(COMPILER_PLUGINS_COM_IS_CLANG)
     fi
 else
     if test "$enable_compiler_plugins" = "yes"; then
@@ -7343,6 +7356,7 @@ else
     fi
 fi
 AC_SUBST(COMPILER_PLUGINS)
+AC_SUBST(COMPILER_PLUGINS_COM_IS_CLANG)
 AC_SUBST(COMPILER_PLUGINS_CXX)
 AC_SUBST(COMPILER_PLUGINS_CXXFLAGS)
 AC_SUBST(COMPILER_PLUGINS_CXX_LINKFLAGS)