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On 05/10/2016 09:36 PM, julien2412 wrote:
On pc Debianx86-64 with master sources, I've got this error:
/home/julien/lo/libreoffice/sc/source/core/data/markmulti.cxx: In member
function ‘void ScMultiSel::SetMarkArea(SCCOL, SCCOL, SCROW, SCROW, bool)’:
/home/julien/lo/libreoffice/sc/source/core/data/markmulti.cxx:242:50: error:
assuming signed overflow does not occur when assuming that (X + c) >= X is
always true [-Werror=strict-overflow]
             while ( nBeg != MAXROWCOUNT && nLast < nEndRow )

^
cc1plus: all warnings being treated as errors

Searching on Opengrok, here are their type:
SCROW nBeg, nLast = nEndRow + 1; (see
http://opengrok.libreoffice.org/xref/core/sc/source/core/data/markmulti.cxx#225)
void ScMultiSel::SetMarkArea( SCCOL nStartCol, SCCOL nEndCol, SCROW
nStartRow, SCROW nEndRow, bool bMark ) (line 206 of same file)

This is a very dreaded warning from the GCC compiler. It appears to often be emitted at stages late in the compilation pipeline, when the internal code representation that triggers the warning no longer maps to the original source code in a comprehensible way. It also appears to be emitted more often when compiling with higher optimization levels. (For example, it appears to be emitted after aggressively inlining code, or after instantiating a specific template specialization.) Also, it appears that different versions of GCC suffer from different ways in which this warning gets emitted in presumably bogus ways.

For an example of how one---known bogus---incarnation of that problem had been addressed see <https://cgit.freedesktop.org/libreoffice/core/commit/?id=897c8af7948aae8f3e3014f9f23846ef1ca5c6cd> "Silence bogus GCC 4.9 -Werror=strict-overflow".

Other warning I got is:
/home/julien/lo/libreoffice/vcl/unx/gtk/gtksalmenu.cxx: In function
‘MenuAndId {anonymous}::decode_command(const gchar*)’:
/home/julien/lo/libreoffice/vcl/unx/gtk/gtksalmenu.cxx:892:17: error: unused
variable ‘sWindow’ [-Werror=unused-variable]
         OString sWindow = sCommand.getToken(0, '-', nIndex);
                        ^
Indeed sWindow is only used in line 898:
assert(sWindow == "window" && pSalSubMenu);

Yes, that's a commonly experienced problem with assert, where its argument gets completely ignored under NDEBUG. One way to avoid the warning is to cast sWindow to void.

Context


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