libgcc7 fails to build in OSX Tiger

[SamBushman]

As a part of building python311 on my Power Mac G5 running OSX 10.4.11 macports attempted to build the libgcc7 dependency. It appears to have failed with errors such as:

:info:build /opt/local/var/macports/buils/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/gcc-7.5.0/gcc/fold-const.c:6714: error: 'LT_eXPR' was not declared in this scope

Unfortunately I'm not familiar enough with how libgcc builds to provide much context.

[SamBushman]

Output log from failed build

[ryandesign (Ryan Carsten Schmidt)]

Replying to SamBushman:

:info:build /opt/local/var/macports/buils/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/gcc-7.5.0/gcc/fold-const.c:6714: error: 'LT_eXPR' was not declared in this scope

Line 6714 of fold-const.c in gcc 7.5.0 actually mentions LT_EXPR, not LT_eXPR:

​https://github.com/gcc-mirror/gcc/blob/releases/gcc-7.5.0/gcc/fold-const.c#L6714

It sounds like a single-bit error has occurred on your computer during the extraction of the gcc 7.5.0 source code (probably a ​soft error):

E is 0x65 is 0b1100101
e is 0x45 is 0b1000101

Hopefully only one single-bit error has occurred, and you can edit the fold-const.c file and replace the erroneous LT_eXPR on line 6714 with the correct LT_EXPR and then reattempt your port install or upgrade.

Alternatively, you could sudo port clean libgcc7 and try again and the same single-bit error probably won't occur again, but this is a large port that will take hours or days to build on a PowerPC Mac so you may want to save yourself the time that you've already invested in building the port to this point and instead fix the offending file and continue the build.

Using ​ECC memory, if your computer supports it, can correct single-bit errors before they cause such problems.