Probably won't compile with GCC 10 on Linux (`-fcommon` issue)

[vain]

GCC 10 changed the default from -fcommon to -fno-common:

https://wiki.gentoo.org/wiki/Gcc_10_porting_notes/fno_common

I haven't tested this with your version of Mosaic, only with another fork (https://github.com/yotann/ncsa-mosaic -- because it has been ported to a newer version of libpng, see #8). IMO, it's more than likely that it affects your version as well (I don't see any relevant differences between the two) and wanted to let you know.

One blunt workaround is to add -fcommon:

diff --git a/makefiles/Makefile.linux b/makefiles/Makefile.linux
index 2cea009..ad03902 100755
--- a/makefiles/Makefile.linux
+++ b/makefiles/Makefile.linux
@@ -225,7 +225,7 @@ customflags =
 
 # ---------------------- END OF CUSTOMIZABLE OPTIONS -------------------------
 
-CFLAGS = -g $(sysconfigflags) $(prereleaseflags)
+CFLAGS = -fcommon -g $(sysconfigflags) $(prereleaseflags)
 
 # Don't worry about these -- for development purposes only.
 PURIFY = purify

As the Gentoo wiki points out, though, this is not an ideal solution. It also outlines nicely what should be done instead.

[vain]

Sorry, forgot to add the actual errors that I get:

/usr/bin/ld: ../libwww2/libwww.a(HTTP.o):/home/void/work/arch-packages/src/ncsa-mosaic/libwww2/../src/kcms.h:3: multiple definition of `KCMS_Enabled'; kcms.o:/home/void/work/arch-packages/src/ncsa-mosaic/src/kcms.h:3: first defined here
/usr/bin/ld: ../libwww2/libwww.a(HTTP.o):/home/void/work/arch-packages/src/ncsa-mosaic/libwww2/../src/kcms.h:4: multiple definition of `KCMS_Return_Format'; kcms.o:/home/void/work/arch-packages/src/ncsa-mosaic/src/kcms.h:4: first defined here
/usr/bin/ld: ../libhtmlw/libhtmlw.a(HTMLformat.o):/home/void/work/arch-packages/src/ncsa-mosaic/libhtmlw/HTMLformat.c:57: multiple definition of `Tv'; xpmread.o:/home/void/work/arch-packages/src/ncsa-mosaic/src/xpmread.c:84: first defined here
/usr/bin/ld: ../libhtmlw/libhtmlw.a(HTMLformat.o):/home/void/work/arch-packages/src/ncsa-mosaic/libhtmlw/HTMLformat.c:58: multiple definition of `Tz'; xpmread.o:/home/void/work/arch-packages/src/ncsa-mosaic/src/xpmread.c:85: first defined here
/usr/bin/ld: ../libhtmlw/libhtmlw.a(HTMLparse.o):/home/void/work/arch-packages/src/ncsa-mosaic/libhtmlw/HTMLparse.c:57: multiple definition of `Tv'; xpmread.o:/home/void/work/arch-packages/src/ncsa-mosaic/src/xpmread.c:84: first defined here
/usr/bin/ld: ../libhtmlw/libhtmlw.a(HTMLparse.o):/home/void/work/arch-packages/src/ncsa-mosaic/libhtmlw/HTMLparse.c:58: multiple definition of `Tz'; xpmread.o:/home/void/work/arch-packages/src/ncsa-mosaic/src/xpmread.c:85: first defined here

[ThePlaneGuy45]

dude, this is a browser from 1993, do you expect it to work on a modern computer?

[emrecio]

Fingers crossed @ThePlaneGuy45

[clausecker]

@ThePlaneGuy45 Why should it not work? I recall that I managed to build a Linux binary just a few years ago. The only problem since is that libpng has changed in incompatible ways, but even that can be patched easily.

[legooolas]

@ThePlaneGuy45 Builds and runs fine once the CFLAGS setting is changed when building with gcc 10, so this is still working -- and why not? :D

[neozeed]

I can confirm with Ubuntu 22.04.1 LTS & gcc 11.3.0 (gcc version 11.3.0 (Ubuntu 11.3.0-1ubuntu1~22.04)) that -fcommon lets it build & run!

[smallpotato000]

I can confirm with Ubuntu 22.04.1 LTS & gcc 11.3.0 (gcc version 11.3.0 (Ubuntu 11.3.0-1ubuntu1~22.04)) that -fcommon lets it build & run!

Yes. Ubuntu Mate 22.04.3 with gcc 11.4.0. Works after adding -fcommon to CFLAGS.