Make error during MacOS Install Due to Forced gcc-15 Compile

[HughLohan]

TL;DR find_gcc.sh forces gcc-15 in some cases, and results in failed one-touch install.

Ran into the below error when trying local one-touch install on MacOS (M4, Sequoia 15.7.3) when both gcc-14 and gcc-15 are available via brew;

make: `grfont.dat' is up to date.
gcc -DPG_PPU -O2 -I. -I/usr/X11R6/include -o pgxwin_server ../src/pgplot/drivers/pgxwin_server.c -L/usr/X11R6/lib -lX11 -L -lgcc -lm -lc
ld: warning: search path '-lgcc' not found
cp -r pgplot /Users/username
-- The C compiler identification is GNU 15.2.0
-- The CXX compiler identification is GNU 15.2.0
-- Checking whether C compiler has -isysroot
-- Checking whether C compiler has -isysroot - yes
-- Checking whether C compiler supports OSX deployment target flag
-- Checking whether C compiler supports OSX deployment target flag - yes
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - failed
-- Check for working C compiler: /opt/homebrew/Cellar/gcc/15.2.0_1/bin/gcc-15
-- Check for working C compiler: /opt/homebrew/Cellar/gcc/15.2.0_1/bin/gcc-15 - broken
CMake Error at /opt/homebrew/share/cmake/Modules/CMakeTestCCompiler.cmake:67 (message):
  The C compiler

    "/opt/homebrew/Cellar/gcc/15.2.0_1/bin/gcc-15"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: '/Users/username/DIFFUSE_INSTALL/develop/DiffuseBuild/CMakeFiles/CMakeScratch/TryCompile-pBRNmk'
    
    Run Build Command(s): /opt/homebrew/bin/cmake -E env VERBOSE=1 /usr/bin/make -f Makefile cmTC_9d243/fast
    /Library/Developer/CommandLineTools/usr/bin/make  -f CMakeFiles/cmTC_9d243.dir/build.make CMakeFiles/cmTC_9d243.dir/build
    CMakeFiles/cmTC_9d243.dir/build.make:82: *** missing separator.  Stop.
    make: *** [cmTC_9d243/fast] Error 2
    
    



  CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
  CMakeLists.txt:5 (project)


-- Configuring incomplete, errors occurred!
CMake Warning:
  Value of CMAKE_CXX_COMPILER_ARG1 contained a newline; truncating


CMake Warning:
  Value of CMAKE_C_COMPILER_ARG1 contained a newline; truncating

I tried steps outlined in this issue, but they did not help. Issue seems to be that compilation fails with gcc-15, but user exports (e.g. export CC="gcc-14") are ignored due to overwrite by ./DIFFUSE_INSTALL/find_gcc.sh. Manually providing gcc-14 path instead of relying on find statement (which defaults to gcc-15) allows compilation to proceed without error;

find_gcc.sh

#!/bin/bash
#
set +e 
DISCUS_GCC="/opt/homebrew/Cellar/gcc@14/14.3.0/bin/gcc-14"
#$(find /usr/local -name 'gcc-??' | fgrep Cellar | fgrep bin)
# echo $DISCUS_GCC
if [[ -z ${DISCUS_GCC} ]]; then
  DISCUS_GCC="/opt/homebrew/Cellar/gcc@14/14.3.0/bin/gcc-14"
#$(find /opt -name 'gcc-??' | fgrep Cellar | fgrep bin)
fi
DISCUS_GXX=${DISCUS_GCC/gcc-/g++-}
# echo $DISCUS_GCC
# echo $DISCUS_GXX
set -e