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Bug 921601 - x11-wm/fvwm-2.7.0-r4 fails to compile (GCC-14-SYSTEM): PictureImageLoader.c:482:13: error: implicit declaration of function png_get_color_type [-Wimplicit-function-declaration]
Summary: x11-wm/fvwm-2.7.0-r4 fails to compile (GCC-14-SYSTEM): PictureImageLoader.c:4...
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: No maintainer - Look at if you want to take care of it
Keywords: PullRequest
Depends on:
Blocks: c99-porting
  Show dependency tree
Reported: 2024-01-08 08:26 UTC by Agostino Sarubbo
Modified: 2024-05-16 11:29 UTC (History)
2 users (show)

See Also:
Package list:
Runtime testing required: ---

build.log (build.log,75.12 KB, text/plain)
2024-01-08 08:26 UTC, Agostino Sarubbo

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Description Agostino Sarubbo gentoo-dev 2024-01-08 08:26:53 UTC

Issue: x11-wm/fvwm-2.7.0-r2 fails to compile (GCC-14-SYSTEM).
Discovered on: amd64 (internal ref: gcc14_tinderbox)

(GCC-14-SYSTEM) in the summary means that the bug was found on a machine that runs gcc-14 but this bug MAY or MAY NOT BE related to the new compiler
Comment 1 Agostino Sarubbo gentoo-dev 2024-01-08 08:26:55 UTC
Created attachment 881669 [details]

build log and emerge --info
Comment 2 Agostino Sarubbo gentoo-dev 2024-05-06 06:51:10 UTC
gcc14_tinderbox has reproduced this issue with version 2.7.0-r4 - Updating summary.
Comment 3 Eli Schwartz gentoo-dev 2024-05-16 05:17:31 UTC
This only occurs when USE=png is disabled.

In /var/tmp/portage/x11-wm/fvwm-2.7.0-r4/work/fvwm-2.7.0/libs/Fpng.h

There is a fair amount of code to abstract away png support using glorious technology such as:

#if PngSupport
typedef png_uint_32 Fpng_uint_32;
#define Fpng_destroy_read_struct(a,b,c) png_destroy_read_struct(a,b,c)
typedef unsigned long Fpng_uint_32;
#define Fpng_destroy_read_struct(a,b,c)

It also exposes png.h to consumers of Fpng.h.

In /var/tmp/portage/x11-wm/fvwm-2.7.0-r4/work/fvwm-2.7.0/libs/PictureImageLoader.c

static Bool PImageLoadPng(FIMAGE_CMD_ARGS)
        if (!PngSupport)
                return False;

And later on in the function, it uses various typedef'ed Fpng* typedefs and defines, but also uses, unconditionally,

png_get_color_type(Fpng_ptr, Finfo_ptr)

no define to hide it.

I personally think the entire thing is silly and standard technology here is to ifdef out the entire function to a stub.

Note: the linked PR is broken. It unconditionally depends on png.h which is quite missing the point. We can just as easily remove the USE flag and unconditionally enable png support.
Comment 4 Brahmajit Das 2024-05-16 11:29:31 UTC
Eli, does something like this look alright to you? I reason that since PNG support is not enabled, we shouldn't be needing this. 

diff --git a/libs/PictureImageLoader.c b/libs/PictureImageLoader.c
index c615081..0a91400 100644
--- a/libs/PictureImageLoader.c
+++ b/libs/PictureImageLoader.c
@@ -468,6 +468,7 @@ Bool PImageLoadPng(FIMAGE_CMD_ARGS)
+#if PngSupport
 	/* TA:  XXX:  (2011-02-14) -- Happy Valentines Day.
 	 * png_get_color_type() defined in libpng 1.5 now hides a data member
@@ -492,6 +493,7 @@ Bool PImageLoadPng(FIMAGE_CMD_ARGS)
 		hasg = 1;
 	if (hasa)