-Werror=sign-conversion Triggered in blf_glyph.c #42797

New Issue

Matt Runion · 2014-12-04T03:15:52+01:00

Matt Runion commented

2014-12-04 03:15:52 +01:00

System Information
Arch Linux 64-bit -- latest updated, no TESTING
i7, 8GB RAM
nVidia GTX 870 6GB RAM
gcc 4.9.2-1
gcc-libs 4.9.2-1

Blender Version
Compiled latest from GIT: blender-git-56793.409043c-1

Short description of error
Build fails because of -Werror=sign-conversion triggered from blf_glyph.c lines 265 & 266

Exact steps for others to reproduce the error

The error I'm getting when compiling is:

/tmp/tmp.HuPKkPCapN/blender-git/src/blender/source/blender/blenfont/intern/blf_glyph.c: In function ‘blf_glyph_add’:
/tmp/tmp.HuPKkPCapN/blender-git/src/blender/source/blender/blenfont/intern/blf_glyph.c:265:13: error: conversion to ‘int’ from ‘unsigned int’ may change the sign of the result [-Werror=sign-conversion]
  g->width = bitmap.width;
             ^
/tmp/tmp.HuPKkPCapN/blender-git/src/blender/source/blender/blenfont/intern/blf_glyph.c:266:14: error: conversion to ‘int’ from ‘unsigned int’ may change the sign of the result [-Werror=sign-conversion]
  g->height = bitmap.rows;
              ^
cc1: some warnings being treated as errors
source/blender/blenfont/CMakeFiles/bf_blenfont.dir/build.make:123: recipe for target 'source/blender/blenfont/CMakeFiles/bf_blenfont.dir/intern/blf_glyph.c.o' failed
make[2]: *** [source/blender/blenfont/CMakeFiles/bf_blenfont.dir/intern/blf_glyph.c.o] Error 1
CMakeFiles/Makefile2:4889: recipe for target 'source/blender/blenfont/CMakeFiles/bf_blenfont.dir/all' failed
make[1]: *** [source/blender/blenfont/CMakeFiles/bf_blenfont.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

As you can see, the problem is that the setting -Werror=sign-conversion is catching an uncast type coersion. Lines 265 and 266 (where the error occurs) are:

265    g->width = bitmap.width;
266    g->height = bitmap.rows;

The problem is that g->width/height are type "int", but bitmap.wdith/height are type "unsigned int". That is causing the issue.

I changed the code in this file to:

265    g->width = (int)bitmap.width;
266    g->height = (int)bitmap.rows;

Blender compiled fine with these changes.

This error was NOT present on 11/6, but did start sometime after that. (I don't know the exact date, unfortunately.) It may be important to note that Arch Linux is a "rolling release", so we get the latest releases of packages from up stream. That means gcc is the latest released version. Again, I have no idea if that has anything to do with the issue, but it may be a contribution.

Thanks in advance for all you devs do for Blender!

**System Information** Arch Linux 64-bit -- latest updated, no TESTING i7, 8GB RAM nVidia GTX 870 6GB RAM gcc 4.9.2-1 gcc-libs 4.9.2-1 **Blender Version** Compiled latest from GIT: blender-git-56793.409043c-1 **Short description of error** Build fails because of -Werror=sign-conversion triggered from blf_glyph.c lines 265 & 266 **Exact steps for others to reproduce the error** The error I'm getting when compiling is: ``` /tmp/tmp.HuPKkPCapN/blender-git/src/blender/source/blender/blenfont/intern/blf_glyph.c: In function ‘blf_glyph_add’: /tmp/tmp.HuPKkPCapN/blender-git/src/blender/source/blender/blenfont/intern/blf_glyph.c:265:13: error: conversion to ‘int’ from ‘unsigned int’ may change the sign of the result [-Werror=sign-conversion] g->width = bitmap.width; ^ /tmp/tmp.HuPKkPCapN/blender-git/src/blender/source/blender/blenfont/intern/blf_glyph.c:266:14: error: conversion to ‘int’ from ‘unsigned int’ may change the sign of the result [-Werror=sign-conversion] g->height = bitmap.rows; ^ cc1: some warnings being treated as errors source/blender/blenfont/CMakeFiles/bf_blenfont.dir/build.make:123: recipe for target 'source/blender/blenfont/CMakeFiles/bf_blenfont.dir/intern/blf_glyph.c.o' failed make[2]: *** [source/blender/blenfont/CMakeFiles/bf_blenfont.dir/intern/blf_glyph.c.o] Error 1 CMakeFiles/Makefile2:4889: recipe for target 'source/blender/blenfont/CMakeFiles/bf_blenfont.dir/all' failed make[1]: *** [source/blender/blenfont/CMakeFiles/bf_blenfont.dir/all] Error 2 make[1]: *** Waiting for unfinished jobs.... ``` As you can see, the problem is that the setting -Werror=sign-conversion is catching an uncast type coersion. Lines 265 and 266 (where the error occurs) are: ``` 265 g->width = bitmap.width; 266 g->height = bitmap.rows; ``` The problem is that g->width/height are type "int", but bitmap.wdith/height are type "unsigned int". That is causing the issue. I changed the code in this file to: ``` 265 g->width = (int)bitmap.width; 266 g->height = (int)bitmap.rows; ``` Blender compiled fine with these changes. This error was NOT present on 11/6, but did start sometime after that. (I don't know the exact date, unfortunately.) It may be important to note that Arch Linux is a "rolling release", so we get the latest releases of packages from up stream. That means gcc is the latest released version. Again, I have no idea if that has anything to do with the issue, but it may be a contribution. Thanks in advance for all you devs do for Blender!

Matt Runion commented

2014-12-04 03:15:52 +01:00

Changed status to: 'Open'

Matt Runion commented

2014-12-04 03:15:52 +01:00

Added subscriber: @mrunion

Bastien Montagne commented

2014-12-04 10:22:31 +01:00

Added subscriber: @mont29

Bastien Montagne commented

2014-12-04 10:22:31 +01:00

Thanks for the report, will 'fix' this, but please do not use the tracker for such glitches, IRC (#blendercoders) or ML (bf-committers) should be used in such cases.

And those are warnings, you typically shall not error on them anyway.

Thanks for the report, will 'fix' this, but please do not use the tracker for such glitches, IRC (#blendercoders) or ML (bf-committers) should be used in such cases. And those are warnings, you typically shall not error on them anyway.

blender-admin commented

2014-12-04 10:23:21 +01:00

This issue was referenced by 2420a3c189

This issue was referenced by 2420a3c189951dbe910bd65e3b2c58082bfb4b1b

Bastien Montagne commented

2014-12-04 10:24:29 +01:00

Changed status from 'Open' to: 'Resolved'

Bastien Montagne closed this issue

2014-12-04 10:24:29 +01:00

Bastien Montagne commented

2014-12-04 10:24:29 +01:00

Closed by commit 2420a3c189.

Closed by commit 2420a3c189.

Matt Runion commented

2014-12-04 13:56:33 +01:00

Thank you for looking at this, and fixing it. Thanks also for the direction in reporting it to the proper place. (Though I disagree with your assessment that it's not a bug. But you're I charge and I'm not.)

Also, I do know this is a warning, but you'll notice that the -Werror=sign-conversion caused it to be treated as an error. That is why I called attention to the fact that I'm using gcc 4.9.2, because I haven't had this before, have no settings in my build config that enable it, see no explicit enable/disable of that error in the CMAKE configs, AND it appears that -Werror=sign-conversion needs explicitly disabled now.

I may be wrong in all this, but I am not that familiar with gcc and Blender code, but it seems something has changed in the latest gcc version.

Thanks again!

Thank you for looking at this, and fixing it. Thanks also for the direction in reporting it to the proper place. (Though I disagree with your assessment that it's not a bug. But you're I charge and I'm not.) Also, I do know this is a warning, but you'll notice that the -Werror=sign-conversion caused it to be treated as an error. That is why I called attention to the fact that I'm using gcc 4.9.2, because I haven't had this before, have no settings in my build config that enable it, see no explicit enable/disable of that error in the CMAKE configs, AND it appears that -Werror=sign-conversion needs explicitly disabled now. I may be wrong in all this, but I am not that familiar with gcc and Blender code, but it seems something has changed in the latest gcc version. Thanks again!

Bastien Montagne commented

2014-12-04 15:19:41 +01:00

Ok, thanks for the precisions (gcc is sometimes becoming tediously pedantic about its 'treat-warnings-as-errors' defaults... though I guess being explicit in such cases is always a good thing anyway!).

Bernd Feige commented

2014-12-17 11:19:53 +01:00

Added subscriber: @berndf

Bernd Feige commented

2014-12-17 11:19:53 +01:00

Note that gentoo was bitten by this as well: https://bugs.gentoo.org/show_bug.cgi?id=532640

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

-Werror=sign-conversion Triggered in blf_glyph.c #42797