gcc-postfix.sh

#!/bin/bash
set -e

## Based off of https://raw.githubusercontent.com/stuarteberg/conda-recipes/52dc383192ed824cd4a8faca5da10e4785623c42/gcc-4.8/post-link.sh

export PATH=/opt/rh/devtoolset-2/root/usr/bin/:$PATH
cd /work
install_dir=/opt/lilinjn/gcc-holy-build

PREFIX=${install_dir}

SYSTEM_GCC=/opt/rh/devtoolset-2/root/usr/bin/gcc
if [ ! -e "${SYSTEM_GCC}" ]; then
    echo "There is no $SYSTEM_GCC"
    exit 1
fi


# In this script, we attempt to fix 3 Linux distro portability issues:

#
# Linux Portability Issue #1: "fixed includes"
#

# Remove the headers that gcc "fixed" as part of the gcc build process.
# They kill the gcc binary's portability to other systems,
#   and shouldn't be necessary on ANSI-compliant systems anyway.
# See this informative writeup of the problem:
# http://ewontfix.com/12/
#
# More discussion can be found here:
# https://groups.google.com/a/continuum.io/d/msg/conda/HwUazgD-hJ0/aofO0vD-MhcJ
while read -r x ; do
  grep -q 'It has been auto-edited by fixincludes from' "${x}" \
           && rm -f "${x}" && echo rm -f "${x}"
done < <(find "${PREFIX}"/lib/gcc/*/*/include*/ -name '*.h')

#
# Linux Portability Issue #2: linker needs to locate crtXXX.o
#

# Locate the system's C-runtime object files and link them into the gcc
#  build so they are automatically on the gcc search path.
# (The location of these files varies from one system to the next.)
C_RUNTIME_OBJ_FILES="crt0.o crt1.o crt2.o crt3.o crti.o crtn.o"

c_runtime_obj_files_found=0

# Try locating crtXXX.o in default library search paths
for library_path in $(ld --verbose | grep SEARCH_DIR | sed -r 's/SEARCH_DIR\("=?([^"]*)"\);/ \1/g'); do
    for obj_file in $C_RUNTIME_OBJ_FILES; do
        obj_file_full_path="$library_path/$obj_file"
        if [[ -e "$obj_file_full_path" ]]; then
            cp "$obj_file_full_path" "${PREFIX}/lib/gcc/"*/*/
            c_runtime_obj_files_found=1
        fi
    done
    if [ $c_runtime_obj_files_found -eq 1 ]; then
        break
    fi
done

# Fallback to locating crtXXX.o with system gcc we if couldn't find it in usual places
if [ $c_runtime_obj_files_found -ne 1 ]; then
    echo "Couldn't locate crtXXX.o in default library search paths. You may not have it " \
         "at all. It is usually packaged in libc6-dev/glibc-devel packages. We will try " \
         "to locate crtXXX.o with system installed gcc..."

    for obj_file in $C_RUNTIME_OBJ_FILES; do
        obj_file_full_path=$($SYSTEM_GCC -print-file-name="$obj_file")
        if [[ "$obj_file_full_path" != "$obj_file" ]]; then
            cp "$obj_file_full_path" "${PREFIX}/lib/gcc/"*/*/
            c_runtime_obj_files_found=1
        fi
    done
fi

if [ $c_runtime_obj_files_found -ne 1 ]; then
    >&2 echo "*** Can't install the gcc package unless your system has crtXXX.o. ***"
    exit 1
fi

#
# Linux Portability Issue #3: Compiler needs to locate system headers
#

# Some distros use different system include paths than the ones this gcc binary was built for.
# We'll add these to the standard include path by providing a custom "specs file"

# First create specs file from existing defaults
SPECS_DIR=$(echo "${PREFIX}"/lib/gcc/*/*)
SPECS_FILE="${SPECS_DIR}/specs"
${PREFIX}/bin/gcc -dumpspecs > "${SPECS_FILE}"

# Now add extra include paths to the specs file, one at a time.
# (So far we only know of one: from Ubuntu.)
EXTRA_SYSTEM_INCLUDE_DIRS="/usr/include/x86_64-linux-gnu"

for INCDIR in ${EXTRA_SYSTEM_INCLUDE_DIRS}; do
    # The following sed command will replace these two lines:
    # *cpp:
    # ... yada yada ...
    #
    # With these two lines:
    # *cpp:
    # ... yada yada ... -I${INCDIR}
    sed -i ':a;N;$!ba;s|\(*cpp:\n[^\n]*\)|\1 -isystem '${INCDIR}'|g' "${SPECS_FILE}"
done

## TEST: Here we verify that gcc can build a simple "Hello world" program for both C and C++.
##
## Note: This tests the gcc package's ability to actually function as a compiler.
##       Therefore, packages should never depend on the gcc package as a 'run' dependency,
##       i.e. just for its packaged libraries (they should depend on 'libgcc' instead).
##       That way, if there are systems which can't use this gcc package for its
##       compiler (due to portability issues) can still use packages produced with it.

workdir=$(mktemp -d XXXXXXXXXX) && cd "$workdir"

# Write test programs.
cat > hello.c <<EOF
#include <stdio.h>
int main()
{
    printf("Hello, world! I can compile C.\n");
    return 0;
}
EOF

cat > hello.cpp <<EOF
#include <iostream>
int main()
{
    std::cout << "Hello, world! I can compile C++." << std::endl;
    return 0;
}
EOF

set +e

# Compile.
(
    set -e
    "${PREFIX}/bin/gcc" -o hello_c.out hello.c
    "${PREFIX}/bin/g++" -o hello_cpp.out hello.cpp
)
SUCCESS=$?
if [ $SUCCESS -ne 0 ]; then
    echo "Installation failed: gcc is not able to compile a simple 'Hello, World' program."
    cd .. && rm -r "$workdir"
    exit 1;
fi


# Execute the compiled output.
(
    set -e
    ./hello_c.out > /dev/null
    ./hello_cpp.out > /dev/null
)
SUCCESS=$?
if [ $SUCCESS -ne 0 ]; then
    echo "Installation failed: Compiled test program did not execute cleanly."
    cd .. && rm -r "$workdir"
    exit 1;
fi

cd .. && rm -r "$workdir"