gcc 7.3.1 build - warnings as errors in harfbuzz (original) (raw)

Volker Simonis volker.simonis at gmail.com
Wed Oct 10 17:26:33 UTC 2018

Hi Matthias,

I've looked a little at this error and it is quite strange. First of all, I can't reproduce it with a default gcc 7.3.0 and there doesn't exist an official version of gcc 7.3.1 (at least I couldn't find it). Also, I can't see the real error in the objected code. The values the warning prints ("assuming directive output of 2147488582 bytes" and "output 2 or more bytes (assuming 2147488583) into a destination of size 127") seem to be excessively large. Every other reference for this warning I could google reports much small numbers and I don't see how a double could potentially use 2147488583 characters in the output buffer.

Could this be a problem with the compiler you've used? Could you also ask the people who compiled and patched it?

I did found the GCC bug "[7 Regression] -Wformat-overflow false positive exceeding INT_MAX in glibc sysdeps/posix/tempname.c" [1] which seem to resemble to the output you see, but that should have been fixed already in the 7.0 release.

Regards, Volker

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79275

On Wed, Oct 10, 2018 at 3:14 PM Baesken, Matthias <matthias.baesken at sap.com> wrote:

Hello , when compiling jdk/jdk with gcc 7.3.1 on linux x8664 (or also on linux ppc64) I run into this build error :

/openjdk/jdkjustclone/jdk/src/java.desktop/share/native/libfontmanager/harfbuzz/hb-common.cc: In function 'void hbvariationtostring(hbvariationt*, char*, unsigned int)': /openjdk/jdkjustclone/jdk/src/java.desktop/share/native/libfontmanager/harfbuzz/hb-common.cc:1066:27: error: '%g' directive output between 1 and 18446744073709551615 bytes may cause result to exceed 'INTMAX' [-Werror=format-truncation=] len += MAX (0, snprintf (s + len, ARRAYLENGTH (s) - len, "%g", variation->value)); ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /openjdk/jdkjustclone/jdk/src/java.desktop/share/native/libfontmanager/harfbuzz/hb-common.cc:1066:27: note: assuming directive output of 2147488582 bytes cc1plus: all warnings being treated as errors (build is a product - build) Setting –disable-warnings-as-errors works as a workaround , but of course this is not really what we want to do . Fixing in the harfbuzz sources in OpenJDk might be also not so nice because it would clash with imports of new versions of harfbuzz . Do you think we could disable the specific warning for the library compilation ? Any other great suggestions ? Thanks, Matthias

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