[Libreoffice-commits] core.git: 3 commits - config_host.mk.in configure.ac hwpfilter/source include/vcl solenv/gbuild vcl/source
Libreoffice Gerrit user
logerrit at kemper.freedesktop.org
Mon Jan 21 08:38:35 UTC 2019
config_host.mk.in | 1
configure.ac | 57 +++++++++++++++++++++++++++++++++
hwpfilter/source/hfont.cxx | 4 +-
hwpfilter/source/hstyle.cxx | 13 ++++++-
include/vcl/pngread.hxx | 2 -
solenv/gbuild/platform/com_GCC_defs.mk | 4 ++
vcl/source/gdi/pngread.cxx | 2 +
7 files changed, 80 insertions(+), 3 deletions(-)
New commits:
commit fed7c3deb3f4ec81f78967c2d7f3c4554398cb9d
Author: Stephan Bergmann <sbergman at redhat.com>
AuthorDate: Fri Jan 18 16:13:57 2019 +0100
Commit: Stephan Bergmann <sbergman at redhat.com>
CommitDate: Mon Jan 21 09:38:27 2019 +0100
Slience bogus -Werror=maybe-uninitialized
...as emitted by at least GCC 8.2 with --enable-optimized, e.g. at:
> In file included from include/rtl/ustring.hxx:37,
> from include/cppuhelper/factory.hxx:26,
> from unoxml/source/rdf/librdf_repository.hxx:24,
> from unoxml/source/rdf/librdf_repository.cxx:20:
> include/rtl/string.hxx: In static member function ‘static std::shared_ptr<{anonymous}::librdf_TypeConverter::Node> {anonymous}::librdf_TypeConverter::extractNode_NoLock(const com::sun::star::uno::Reference<com::sun::star::rdf::XNode>&)’:
> include/rtl/string.hxx:294:27: error: ‘*((void*)(& type)+8).rtl::OString::pData’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> rtl_string_release( pData );
> ~~~~~~~~~~~~~~~~~~^~~~~~~~~
> unoxml/source/rdf/librdf_repository.cxx:2094:30: note: ‘*((void*)(& type)+8).rtl::OString::pData’ was declared here
> boost::optional<OString> type;
> ^~~~
This appears to be a common pattern of false positives with uses of
boost::optional, common enough to disable the warning globally for affected
compilers, even if there would also be useful findings by that warning (e.g.,
<https://gerrit.libreoffice.org/#/c/66619/> "Fix -Werror=maybe-uninitialized").
I didn't bother to file a GCC bug for the reproducer used in configure.ac,
<https://gcc.gnu.org/bugzilla/buglist.cgi?quicksearch=maybe-uninitialized>
already shows lots of open bugs in that area, and the documentation at
<https://gcc.gnu.org/onlinedocs/gcc-8.2.0/gcc/Warning-Options.html> states that
"GCC may not be able to determine when the code is correct in spite of appearing
to have an error."
(Clang appears to not support -Wmaybe-uninitialized at all, so exclude it from
the configure.ac check, to not have the check's failure result in an unsupported
-Wno-maybe-uninitialized end up on the compiler command line.)
Change-Id: Ifb9ca4c342750eae54f7e1a01506101310484c7e
Reviewed-on: https://gerrit.libreoffice.org/66621
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman at redhat.com>
diff --git a/config_host.mk.in b/config_host.mk.in
index 55a4c00c8219..aa64c32b77ab 100644
--- a/config_host.mk.in
+++ b/config_host.mk.in
@@ -244,6 +244,7 @@ export GTK_PRINT_CFLAGS=$(gb_SPACE)@GTK_PRINT_CFLAGS@
export GTK_PRINT_LIBS=$(gb_SPACE)@GTK_PRINT_LIBS@
export USING_X11=@USING_X11@
export HAMCREST_JAR=@HAMCREST_JAR@
+export HAVE_BROKEN_GCC_WMAYBE_UNINITIALIZED=@HAVE_BROKEN_GCC_WMAYBE_UNINITIALIZED@
export HAVE_GCC_AVX=@HAVE_GCC_AVX@
export HAVE_GCC_STACK_PROTECTOR_STRONG=@HAVE_GCC_STACK_PROTECTOR_STRONG@
export HAVE_GCC_BUILTIN_ATOMIC=@HAVE_GCC_BUILTIN_ATOMIC@
diff --git a/configure.ac b/configure.ac
index fe0d792ba7fe..19f1f5803d5e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -6540,6 +6540,63 @@ AC_COMPILE_IFELSE([AC_LANG_SOURCE([
CXXFLAGS=$save_CXXFLAGS
AC_LANG_POP([C++])
+dnl At least GCC 8.2 with -O2 (i.e., --enable-optimized) causes a false-positive -Wmaybe-
+dnl uninitialized warning for code like
+dnl
+dnl OString f();
+dnl boost::optional<OString> * g(bool b) {
+dnl boost::optional<OString> o;
+dnl if (b) o = f();
+dnl return new boost::optional<OString>(o);
+dnl }
+dnl
+dnl (as is e.g. present, in a slightly more elaborate form, in
+dnl librdf_TypeConverter::extractNode_NoLock in unoxml/source/rdf/librdf_repository.cxx); the below
+dnl code is meant to be a faithfully stripped-down and self-contained version of the above code:
+HAVE_BROKEN_GCC_WMAYBE_UNINITIALIZED=
+if test "$GCC" = yes && test "$COM_IS_CLANG" != TRUE; then
+ AC_MSG_CHECKING([whether $CXX might report false -Werror=maybe-uninitialized])
+ AC_LANG_PUSH([C++])
+ save_CXXFLAGS=$CXXFLAGS
+ CXXFLAGS="$CXXFLAGS $CXXFLAGS_CXX11 -Werror -Wmaybe-uninitialized"
+ if test "$ENABLE_OPTIMIZED" = TRUE; then
+ CXXFLAGS="$CXXFLAGS -O2"
+ else
+ CXXFLAGS="$CXXFLAGS -O0"
+ fi
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+ #include <new>
+ void f1(int);
+ struct S1 {
+ ~S1() { f1(n); }
+ int n = 0;
+ };
+ struct S2 {
+ S2() {}
+ S2(S2 const & s) { if (s.init) set(*reinterpret_cast<S1 const *>(s.stg)); }
+ ~S2() { if (init) reinterpret_cast<S1 *>(stg)->S1::~S1(); }
+ void set(S1 s) {
+ new (stg) S1(s);
+ init = true;
+ }
+ bool init = false;
+ char stg[sizeof (S1)];
+ } ;
+ S1 f2();
+ S2 * f3(bool b) {
+ S2 o;
+ if (b) o.set(f2());
+ return new S2(o);
+ }
+ ]])], [AC_MSG_RESULT([no])], [
+ HAVE_BROKEN_GCC_WMAYBE_UNINITIALIZED=TRUE
+ AC_MSG_RESULT([yes])
+ ])
+ CXXFLAGS=$save_CXXFLAGS
+ AC_LANG_POP([C++])
+fi
+AC_SUBST([HAVE_BROKEN_GCC_WMAYBE_UNINITIALIZED])
+
dnl ===================================================================
dnl system stl sanity tests
dnl ===================================================================
diff --git a/solenv/gbuild/platform/com_GCC_defs.mk b/solenv/gbuild/platform/com_GCC_defs.mk
index 1048a1375327..14d82ccdc0e2 100644
--- a/solenv/gbuild/platform/com_GCC_defs.mk
+++ b/solenv/gbuild/platform/com_GCC_defs.mk
@@ -79,6 +79,10 @@ gb_CXXFLAGS_COMMON := \
-fno-common \
-pipe \
+ifeq ($(HAVE_BROKEN_GCC_WMAYBE_UNINITIALIZED),TRUE)
+gb_CXXFLAGS_COMMON += -Wno-maybe-uninitialized
+endif
+
gb_CXXFLAGS_Wundef = -Wno-undef
ifeq ($(ENABLE_GDB_INDEX),TRUE)
commit 26688cf08988ad80f7412d00dba749faa06832ad
Author: Stephan Bergmann <sbergman at redhat.com>
AuthorDate: Fri Jan 18 16:11:27 2019 +0100
Commit: Stephan Bergmann <sbergman at redhat.com>
CommitDate: Mon Jan 21 09:38:13 2019 +0100
Avoid -Werror=stringop-truncation
...as emitted by at least GCC 8.2 with --enable-optimized. These are not
actually problems, as in both cases strncpy(p,...,N-1) is used to copy a
string into an area p of length N that has initially been zero-initialized, so
p[N-1] will already contain NUL. But add the (redundant) p[N-1]=NUL just in
case, and to silence GCC (where the documentation explicitly recommends this
additional write as a way to silence the warning). Unfortunately, in hstyle.cxx
at least GCC 8.2 with --enable-optimized would still emit the warning, even
though it uses the recommended way of handling it, so needs to be silenced with
a #pragma.
Change-Id: Ie41f420c732c2bfb699903ebd21ce1a89dd2b236
Reviewed-on: https://gerrit.libreoffice.org/66620
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman at redhat.com>
diff --git a/hwpfilter/source/hfont.cxx b/hwpfilter/source/hfont.cxx
index e5c23a88199b..1a96b1797463 100644
--- a/hwpfilter/source/hfont.cxx
+++ b/hwpfilter/source/hfont.cxx
@@ -47,7 +47,9 @@ void HWPFont::AddFont(int lang, const char *font)
nfonts = nFonts[lang];
if (MAXFONTS <= nfonts)
return;
- strncpy(fontnames[lang].get() + FONTNAMELEN * nfonts, font, FONTNAMELEN - 1);
+ auto const p = fontnames[lang].get() + FONTNAMELEN * nfonts;
+ strncpy(p, font, FONTNAMELEN - 1);
+ p[FONTNAMELEN - 1] = '\0'; // just in case, even though the array is zero-initialized
nFonts[lang]++;
}
diff --git a/hwpfilter/source/hstyle.cxx b/hwpfilter/source/hstyle.cxx
index cc3ef07cc987..87fd1efbe978 100644
--- a/hwpfilter/source/hstyle.cxx
+++ b/hwpfilter/source/hstyle.cxx
@@ -66,7 +66,18 @@ void HWPStyle::SetName(int n, char const *name)
if (n >= 0 && n < nstyles)
{
if (name)
- strncpy(DATA[n].name, name, MAXSTYLENAME);
+ {
+#if defined __GNUC__ && __GNUC__ == 8 && __GNUC_MINOR__ == 2 && !defined __clang__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-truncation"
+#endif
+ auto const p = DATA[n].name;
+ strncpy(p, name, MAXSTYLENAME);
+ p[MAXSTYLENAME] = '\0'; // just in case, even though the array is zero-initialized
+#if defined __GNUC__ && __GNUC__ == 8 && __GNUC_MINOR__ == 2 && !defined __clang__
+#pragma GCC diagnostic pop
+#endif
+ }
else
DATA[n].name[0] = 0;
}
commit 3a001a588c43cf8c2c3f6cb6a6796cc1bf8e2683
Author: Stephan Bergmann <sbergman at redhat.com>
AuthorDate: Fri Jan 18 15:58:58 2019 +0100
Commit: Stephan Bergmann <sbergman at redhat.com>
CommitDate: Mon Jan 21 09:38:01 2019 +0100
Fix -Werror=maybe-uninitialized
...as emitted by at least GCC 8.2 with --enable-optimized:
> In file included from vcl/source/gdi/pngread.cxx:27:
> include/vcl/pngread.hxx: In member function ‘bool vcl::PNGReaderImpl::ReadNextChunk()’:
> include/vcl/pngread.hxx:49:12: error: ‘aDummyChunk.vcl::PNGReader::ChunkData::nType’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> struct ChunkData
> ^~~~~~~~~
The immediately relevant part is initializing
sal_uInt32 nType = 0;
in the ChunkData ctor, but while at it, also make the Read*Int32 calls in
PNGReaderImpl::ReadNextChunk more robust.
Change-Id: Id6ad10a4382a8d063fd70c7bac595c3693475ca3
Reviewed-on: https://gerrit.libreoffice.org/66619
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman at redhat.com>
diff --git a/include/vcl/pngread.hxx b/include/vcl/pngread.hxx
index 8992709b3349..31592d9f17ac 100644
--- a/include/vcl/pngread.hxx
+++ b/include/vcl/pngread.hxx
@@ -48,7 +48,7 @@ public:
// retrieve every chunk that resides inside the PNG
struct ChunkData
{
- sal_uInt32 nType;
+ sal_uInt32 nType = 0;
std::vector<sal_uInt8> aData;
};
const std::vector<ChunkData>& GetChunks() const;
diff --git a/vcl/source/gdi/pngread.cxx b/vcl/source/gdi/pngread.cxx
index 78195d5e7c46..b5ac9e430596 100644
--- a/vcl/source/gdi/pngread.cxx
+++ b/vcl/source/gdi/pngread.cxx
@@ -273,6 +273,8 @@ bool PNGReaderImpl::ReadNextChunk()
PNGReader::ChunkData& rChunkData = *maChunkIter;
// read the chunk header
+ mnChunkLen = 0;
+ mnChunkType = 0;
mrPNGStream.ReadInt32( mnChunkLen ).ReadUInt32( mnChunkType );
rChunkData.nType = mnChunkType;
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