Configure step: compiler checks done before basic settings

Until now, the project would first ask for the basic directories, then it
would start testing the compiler. But that was problematic because the
build directory can come from a previous setting (with `./project configure
-e'). Also, it could confuse users to first ask for details, then suddently
tell them that you don't have a working C library! We also need to store
the CPATH variable in the `LOCAL.conf' because in some cases, the compiler
won't work without it.

With this commit, the compiler checking has been moved at the start of the
configure script. Instead of putting the test program in the build
directory, we now make a temporary hidden directory in the source directory
and delete that directory as soon as the tests are done.

In the process, I also noticed that the copyright year of the two hidden
files weren't updated and corrected them.

4 files changed, 409 insertions, 418 deletions

diff --git a/reproduce/analysis/make/initialize.mk b/reproduce/analysis/make/initialize.mk
index fa39699..1137f28 100644
--- a/reproduce/analysis/make/initialize.mk
+++ b/reproduce/analysis/make/initialize.mk
@@ -140,6 +140,12 @@ export SHELL := $(installdir)/bin/bash
 export CPPFLAGS := -I$(installdir)/include
 export LD_LIBRARY_PATH := $(installdir)/lib
 
+# Until we build our own C library, without this, the project's GCC won't
+# be able to compile anything if the host C library isn't in a standard
+# place: in particular Debian-based operatings sytems. On other systems, it
+# will be empty.
+export CPATH := $(SYS_CPATH)
+
 # RPATH is automatically written in macOS, so `DYLD_LIBRARY_PATH' is
 # ultimately redundant. But on some systems, even having a single value
 # causes crashs (see bug #56682). So we'll just give it no value at all.
diff --git a/reproduce/software/bash/configure.sh b/reproduce/software/bash/configure.sh
index 96c4ad0..a6fbc4e 100755
--- a/reproduce/software/bash/configure.sh
+++ b/reproduce/software/bash/configure.sh
@@ -95,6 +95,398 @@ absolute_dir ()
 
 
 
+# Check for C/C++ compilers
+# -------------------------
+#
+# To build the software, we'll need some basic tools (the compilers in
+# particular) to be present.
+hascc=0;
+if type cc > /dev/null 2>/dev/null; then
+    if type c++ > /dev/null 2>/dev/null; then export CC=cc; hascc=1; fi
+else
+    if type gcc > /dev/null 2>/dev/null; then
+        if type g++ > /dev/null 2>/dev/null; then export CC=gcc; hascc=1; fi
+    else
+        if type clang > /dev/null 2>/dev/null; then
+            if type clang++ > /dev/null 2>/dev/null; then export CC=clang; hascc=1; fi
+        fi
+    fi
+fi
+if [ $hascc = 0 ]; then
+    cat <<EOF
+______________________________________________________
+!!!!!!!       C/C++ Compiler NOT FOUND         !!!!!!!
+
+To build the project's software, the host system needs to have basic C and
+C++ compilers. The executables that were checked are 'cc', 'gcc' and
+'clang' for a C compiler, and 'c++', 'g++' and 'clang++' for a C++
+compiler. If you have a relevant compiler that is not checked, please get
+in touch with us (with the form below) so we add it:
+
+  https://savannah.nongnu.org/support/?func=additem&group=reproduce
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+EOF
+    exit 1
+fi
+
+
+
+
+
+# Special directory for compiler testing
+# --------------------------------------
+#
+# This directory will be deleted when the compiler testing is finished.
+compilertestdir=.compiler_test_dir_please_delete
+if ! [ -d $compilertestdir ]; then mkdir $compilertestdir; fi
+
+
+
+
+
+# Check C compiler
+# ----------------
+gcc_works=0
+testprog=$compilertestdir/test
+testsource=$compilertestdir/test.c
+echo; echo; echo "Checking host C compiler...";
+cat > $testsource <<EOF
+#include <stdio.h>
+#include <stdlib.h>
+int main(void){printf("...C compiler works.\n");
+               return EXIT_SUCCESS;}
+EOF
+if $CC $testsource -o$testprog && $testprog; then
+    rm $testsource $testprog
+else
+    rm $testsource
+    cat <<EOF
+
+______________________________________________________
+!!!!!!!        C compiler doesn't work         !!!!!!!
+
+Host C compiler ('gcc') can't build a simple program.
+
+A working C compiler is necessary for building the project's software.
+Please use the error message above to find a good solution and re-run the
+project configuration.
+
+If you can't find a solution, please send the error message above to the
+link below and we'll try to help
+
+https://savannah.nongnu.org/support/?func=additem&group=reproduce
+
+TIP: Once you find the solution, you can use the '-e' option to use
+existing configuration:
+
+   $ ./project configure -e
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+EOF
+    exit 1
+fi
+
+
+
+
+
+# See if the linker accepts -Wl,-rpath-link
+# -----------------------------------------
+#
+# `-rpath-link' is used to write the information of the linked shared
+# library into the shared object (library or program). But some versions of
+# LLVM's linker don't accept it an can cause problems.
+cat > $testsource <<EOF
+#include <stdio.h>
+#include <stdlib.h>
+int main(void) {return EXIT_SUCCESS;}
+EOF
+if $CC $testsource -o$testprog -Wl,-rpath-link 2>/dev/null > /dev/null; then
+    export rpath_command="-Wl,-rpath-link=$instdir/lib"
+else
+    export rpath_command=""
+fi
+rm -f $testprog $testsource
+
+
+
+
+
+# See if we need the dynamic-linker (-ldl)
+# ----------------------------------------
+#
+# Some programs (like Wget) need dynamic loading (using `libdl'). On
+# GNU/Linux systems, we'll need the `-ldl' flag to link such programs.  But
+# Mac OS doesn't need any explicit linking. So we'll check here to see if
+# it is present (thus necessary) or not.
+cat > $testsource <<EOF
+#include <stdio.h>
+#include <dlfcn.h>
+int
+main(void) {
+    void *handle=dlopen ("/lib/CEDD_LIB.so.6", RTLD_LAZY);
+    return 0;
+}
+EOF
+if $CC $testsource -o$testprog 2>/dev/null > /dev/null; then
+    needs_ldl=no;
+else
+    needs_ldl=yes;
+fi
+rm -f $testprog $testsource
+
+
+
+
+
+# See if the C compiler can build static libraries
+# ------------------------------------------------
+
+# We are manually only working with shared libraries: because some
+# high-level programs like Wget and cURL need dynamic linking and if we
+# build the libraries statically, our own builds will be ignored and these
+# programs will go and find their necessary libraries on the host system.
+#
+# Another good advantage of shared libraries is that we can actually use
+# the shared library tool of the system (`ldd' with GNU C Library) and see
+# exactly where each linked library comes from. But in static building,
+# unless you follow the build closely, its not easy to see if the source of
+# the library came from the system or our build.
+static_build=no
+
+
+
+
+
+# If we are on a Mac OS system
+# ----------------------------
+#
+# For the time being, we'll use the existance of `otool' to see if we are
+# on a Mac OS system or not. Some tools (for example OpenSSL) need to know
+# this.
+#
+# On Mac OS, the building of GCC crashes sometimes while building libiberty
+# with CLang's `g++'. Until we find a solution, we'll just use the host's C
+# compiler.
+if type otool > /dev/null 2>/dev/null; then
+    host_cc=1
+    on_mac_os=yes
+else
+    host_cc=0
+    on_mac_os=no
+fi
+
+
+
+
+
+# Necessary C library element positions
+# -------------------------------------
+#
+# On some systems (in particular Debian-based OSs), the static C library
+# and necessary headers in a non-standard place, and we can't build GCC. So
+# we need to find them first. The `sys/cdefs.h' header is also in a
+# similarly different location.
+sys_cpath=""
+sys_library_path=""
+if [ x"$$on_mac_os" != xyes ]; then
+
+    # Get the GCC target name of the compiler, when its given, special
+    # C libraries and headers are in a sub-directory of the host.
+    gcctarget=$(gcc -v 2>&1 \
+                    | tr ' ' '\n' \
+                    | awk '/\-\-target/' \
+                    | sed -e's/\-\-target=//')
+    if [ x"$gcctarget" != x ]; then
+        if [ -f /usr/lib/$gcctarget/libc.a ]; then
+            export sys_library_path=/usr/lib/$gcctarget
+            export sys_cpath=/usr/include/$gcctarget
+        fi
+    fi
+
+    # For a check:
+    #echo "sys_library_path: $sys_library_path"
+    #echo "sys_cpath: $sys_cpath"
+fi
+
+
+
+
+
+# See if a link-able static C library exists
+# ------------------------------------------
+#
+# After building GCC, we must use PatchELF to correct its RPATHs. However,
+# PatchELF links internally with `libstdc++'. So a dynamicly linked
+# PatchELF cannot be used to correct the links to `libstdc++' in general
+# (on some systems this causes no problem, but on others it doesn't!).
+#
+# However, to build a Static PatchELF, we need to be able to link with the
+# static C library, which is not always available on some GNU/Linux
+# systems. Therefore we need to check this here. If we can't build a static
+# PatchELF, we won't build any GCC either.
+if [ x"$host_cc" = x0 ]; then
+    echo; echo; echo "Checking if static C library is available...";
+    cat > $testsource <<EOF
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/cdefs.h>
+int main(void){printf("...yes\n");
+               return EXIT_SUCCESS;}
+EOF
+    cc_call="$CC $testsource $CPPFLAGS $LDFLAGS -o$testprog -static -lc"
+    if $cc_call && $testprog; then
+        gccwarning=0
+        good_static_libc=1
+        rm $testsource $testprog
+    else
+        echo; echo "Compilation command:"; echo "$cc_call"
+        good_static_libc=0
+        rm $testsource
+        gccwarning=1
+        host_cc=1
+        cat <<EOF
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+!!!!!!!!!!!!!!!!!!!!!!         Warning        !!!!!!!!!!!!!!!!!!!!!!
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+The 'sys/cdefs.h' header cannot be included, or a usable static C library
+('libc.a', in any directory) cannot be used with the current settings of
+this system. SEE THE ERROR MESSAGE ABOVE.
+
+Because of this, we can't build GCC. You either 1) don't have them, or 2)
+the default system environment aren't enough to find them.
+
+1) If you don't have them, your operating system provides them as separate
+packages that you must manually install. Please look into your operating
+system documentation or contact someone familiar with it. For example on
+some Redhat-based GNU/Linux distributions, the static C library package can
+be installed with this command:
+
+    $ sudo yum install glibc-static
+
+2) If you have 'libc.a' and 'sys/cdefs.h', but in a non-standard location (for
+example in '/PATH/TO/STATIC/LIBC/libc.a' and
+'/PATH/TO/SYS/CDEFS_H/sys/cdefs.h'), please run the commands below, then
+re-configure the project to fix this problem.
+
+    $ export LDFLAGS="-L/PATH/TO/STATIC/LIBC \$LDFLAGS"
+    $ export CPPFLAGS="-I/PATH/TO/SYS/CDEFS_H \$LDFLAGS"
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+EOF
+    fi
+fi
+
+# Print a warning if GCC is not meant to be built.
+if [ x"$gccwarning" = x1 ]; then
+        cat <<EOF
+
+PLEASE SEE THE WARNINGS ABOVE.
+
+Since GCC is pretty low-level, this configuration script will continue in 5
+seconds and use your system's C compiler (it won't build a custom GCC). But
+please consider installing the necessary package(s) to complete your C
+compiler, then re-run './project configure'.
+
+EOF
+        sleep 5
+fi
+
+
+
+
+
+# Fortran compiler
+# ----------------
+#
+# If GCC is ultimately build within the project, the user won't need to
+# have a fortran compiler, we'll build it internally for high-level
+# programs. However, when the host C compiler is to be used, the user needs
+# to have a Fortran compiler available.
+if [ $host_cc = 1 ]; then
+
+    # See if a Fortran compiler exists.
+    hasfc=0;
+    if type gfortran > /dev/null 2>/dev/null; then hasfc=1; fi
+    if [ $hasfc = 0 ]; then
+        cat <<EOF
+______________________________________________________
+!!!!!!!      Fortran Compiler NOT FOUND        !!!!!!!
+
+Because the project won't be building its own GCC (which includes a Fortran
+compiler), you need to have a Fortran compiler available. Fortran is
+commonly necessary for many lower-level scientific programs. Currently we
+search for 'gfortran'. If you have a Fortran compiler that is not checked,
+please get in touch with us (with the form below) so we add it:
+
+  https://savannah.nongnu.org/support/?func=additem&group=reproduce
+
+Note: GCC will not be built because you are either using the '--host-cc'
+option, or you are using an operating system that currently has bugs when
+building GCC.
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+EOF
+        exit 1
+    fi
+
+    # See if the Fortran compiler works
+    testsource=$compilertestdir/test.f
+    echo; echo; echo "Checking host Fortran compiler...";
+    echo "      PRINT *, \"... Fortran Compiler works.\""  > $testsource
+    echo "      END"                                      >> $testsource
+    if gfortran $testsource -o$testprog && $testprog; then
+        rm $testsource $testprog
+    else
+        rm $testsource
+        cat <<EOF
+
+______________________________________________________
+!!!!!!!     Fortran compiler doesn't work      !!!!!!!
+
+Host Fortran compiler ('gfortran') can't build a simple program.
+
+A working Fortran compiler is necessary for building some of the project's
+software.  Please use the error message above to find a good solution and
+re-run the project configuration.
+
+If you can't find a solution, please send the error message above to the
+link below and we'll try to help
+
+https://savannah.nongnu.org/support/?func=additem&group=reproduce
+
+TIP: Once you find the solution, you can use the '-e' option to use
+existing configuration:
+
+   $ ./project configure -e
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+EOF
+        exit 1
+    fi
+fi
+
+
+
+
+
+# Delete the compiler testing directory
+# -------------------------------------
+#
+# This directory was made above to make sure the necessary compilers can be
+# run.
+rm -rf $compilertestdir
+
+
+
+
+
 # Inform the user
 # ---------------
 #
@@ -392,6 +784,7 @@ if [ $rewritepconfig = yes ]; then
     sed -e's|@bdir[@]|'"$bdir"'|' \
         -e's|@indir[@]|'"$indir"'|' \
         -e's|@ddir[@]|'"$ddir"'|' \
+        -e's|@sys_cpath[@]|'"$sys_cpath"'|' \
         -e's|@downloader[@]|'"$downloader"'|' \
         -e's|@groupname[@]|'"$reproducible_paper_group_name"'|' \
         $pconf.in >> $pconf
@@ -635,420 +1028,6 @@ fi
 
 
 
-# Check for C/C++ compilers
-# -------------------------
-#
-# To build the software, we'll need some basic tools (the compilers in
-# particular) to be present.
-hascc=0;
-if type cc > /dev/null 2>/dev/null; then
-    if type c++ > /dev/null 2>/dev/null; then export CC=cc; hascc=1; fi
-else
-    if type gcc > /dev/null 2>/dev/null; then
-        if type g++ > /dev/null 2>/dev/null; then export CC=gcc; hascc=1; fi
-    else
-        if type clang > /dev/null 2>/dev/null; then
-            if type clang++ > /dev/null 2>/dev/null; then export CC=clang; hascc=1; fi
-        fi
-    fi
-fi
-if [ $hascc = 0 ]; then
-    cat <<EOF
-______________________________________________________
-!!!!!!!       C/C++ Compiler NOT FOUND         !!!!!!!
-
-To build the project's software, the host system needs to have basic C and
-C++ compilers. The executables that were checked are 'cc', 'gcc' and
-'clang' for a C compiler, and 'c++', 'g++' and 'clang++' for a C++
-compiler. If you have a relevant compiler that is not checked, please get
-in touch with us (with the form below) so we add it:
-
-  https://savannah.nongnu.org/support/?func=additem&group=reproduce
-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
-EOF
-    exit 1
-fi
-
-
-
-
-
-# Check C compiler
-# ----------------
-gcc_works=0
-testprog=$tmpblddir/test-c
-testsource=$tmpblddir/test.c
-echo; echo; echo "Checking host C compiler...";
-cat > $testsource <<EOF
-#include <stdio.h>
-#include <stdlib.h>
-int main(void){printf("...C compiler works.\n");
-               return EXIT_SUCCESS;}
-EOF
-if $CC $testsource -o$testprog && $testprog; then
-    rm $testsource $testprog
-else
-    cat <<EOF
-
-______________________________________________________
-!!!!!!!        C compiler doesn't work         !!!!!!!
-
-Host C compiler ('gcc') can't build a simple program.
-
-A working C compiler is necessary for building the project's software.
-Please use the error message above to find a good solution and re-run the
-project configuration.
-
-If you can't find a solution, please send the error message above to the
-link below and we'll try to help
-
-https://savannah.nongnu.org/support/?func=additem&group=reproduce
-
-TIP: Once you find the solution, you can use the '-e' option to use
-existing configuration:
-
-   $ ./project configure -e
-
-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
-EOF
-    exit 1
-fi
-
-
-
-
-
-# See if the linker accepts -Wl,-rpath-link
-# -----------------------------------------
-#
-# `-rpath-link' is used to write the information of the linked shared
-# library into the shared object (library or program). But some versions of
-# LLVM's linker don't accept it an can cause problems.
-oprog=$sdir/rpath-test
-cprog=$sdir/rpath-test.c
-cat > $cprog <<EOF
-#include <stdio.h>
-#include <stdlib.h>
-int main(void) {return EXIT_SUCCESS;}
-EOF
-if $CC $cprog -o$oprog -Wl,-rpath-link 2>/dev/null > /dev/null; then
-    export rpath_command="-Wl,-rpath-link=$instdir/lib"
-else
-    export rpath_command=""
-fi
-rm -f $oprog $cprog
-
-
-
-
-
-# See if we need the dynamic-linker (-ldl)
-# ----------------------------------------
-#
-# Some programs (like Wget) need dynamic loading (using `libdl'). On
-# GNU/Linux systems, we'll need the `-ldl' flag to link such programs.  But
-# Mac OS doesn't need any explicit linking. So we'll check here to see if
-# it is present (thus necessary) or not.
-oprog=$sdir/ldl-test
-cprog=$sdir/ldl-test.c
-cat > $cprog <<EOF
-#include <stdio.h>
-#include <dlfcn.h>
-int
-main(void) {
-    void *handle=dlopen ("/lib/CEDD_LIB.so.6", RTLD_LAZY);
-    return 0;
-}
-EOF
-if $CC $cprog -o$oprog 2>/dev/null > /dev/null; then
-    needs_ldl=no;
-else
-    needs_ldl=yes;
-fi
-rm -f $oprog $cprog
-
-
-
-
-
-# See if the C compiler can build static libraries
-# ------------------------------------------------
-
-# We are manually only working with shared libraries: because some
-# high-level programs like Wget and cURL need dynamic linking and if we
-# build the libraries statically, our own builds will be ignored and these
-# programs will go and find their necessary libraries on the host system.
-#
-# Another good advantage of shared libraries is that we can actually use
-# the shared library tool of the system (`ldd' with GNU C Library) and see
-# exactly where each linked library comes from. But in static building,
-# unless you follow the build closely, its not easy to see if the source of
-# the library came from the system or our build.
-static_build=no
-
-#oprog=$sdir/static-test
-#cprog=$sdir/static-test.c
-#echo "#include <stdio.h>"          > $cprog
-#echo "int main(void) {return 0;}" >> $cprog
-#if [ x$CC = x ]; then CC=gcc; fi;
-#if $CC $cprog -o$oprog -static > /dev/null; then
-#    export static_build="yes"
-#else
-#    export static_build="no"
-#fi
-#rm -f $oprog $cprog
-#if [ $printnotice = yes ] && [ $static_build = "no" ]; then
-#    cat <<EOF
-#_________________________________________________________________________
-#!!!!!!!!!!!!!!!!!!!!!!!!!!!!      WARNING      !!!!!!!!!!!!!!!!!!!!!!!!!!
-#
-#Your system's C compiler ('$CC') doesn't support building static
-#libraries. Therefore the dependencies will be built dynamically. This means
-#that they will depend more strongly on changes/updates in the host
-#system. For high-level applications (like most research projects in natural
-#sciences), this shouldn't be a significant problem.
-#
-#But generally, for reproducibility, its better to build static libraries
-#and programs. For more on their difference (and generally an introduction
-#on linking), please see the link below:
-#
-#https://www.gnu.org/software/gnuastro/manual/html_node/Linking.html
-#
-#If you have other compilers on your system, you can select a different
-#compiler by setting the 'CC' environment variable before running
-#'./project configure'.
-#
-#!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-#
-#EOF
-#    sleep 5
-#fi
-
-
-
-
-
-# If we are on a Mac OS system
-# ----------------------------
-#
-# For the time being, we'll use the existance of `otool' to see if we are
-# on a Mac OS system or not. Some tools (for example OpenSSL) need to know
-# this.
-#
-# On Mac OS, the building of GCC crashes sometimes while building libiberty
-# with CLang's `g++'. Until we find a solution, we'll just use the host's C
-# compiler.
-if type otool > /dev/null 2>/dev/null; then
-    host_cc=1
-    on_mac_os=yes
-else
-    host_cc=0
-    on_mac_os=no
-fi
-
-
-
-
-
-# Necessary C library element positions
-# -------------------------------------
-#
-# On some systems (in particular Debian-based OSs), the static C library
-# and necessary headers in a non-standard place, and we can't build GCC. So
-# we need to find them first. The `sys/cdefs.h' header is also in a
-# similarly different location.
-sys_cppflags=""
-sys_library_path=""
-if [ x"$$on_mac_os" != xyes ]; then
-
-    # Get the GCC target name of the compiler, when its given, special
-    # C libraries and headers are in a sub-directory of the host.
-    gcctarget=$(gcc -v 2>&1 \
-                    | tr ' ' '\n' \
-                    | awk '/\-\-target/' \
-                    | sed -e's/\-\-target=//')
-    if [ x"$gcctarget" != x ]; then
-        if [ -f /usr/lib/$gcctarget/libc.a ]; then
-            export sys_library_path=/usr/lib/$gcctarget
-            export sys_cpath=/usr/include/$gcctarget
-        fi
-    fi
-
-    # For a check:
-    #echo "sys_library_path: $sys_library_path"
-    #echo "sys_cpath: $sys_cpath"
-fi
-
-
-
-
-
-# See if a link-able static C library exists
-# ------------------------------------------
-#
-# After building GCC, we must use PatchELF to correct its RPATHs. However,
-# PatchELF links internally with `libstdc++'. So a dynamicly linked
-# PatchELF cannot be used to correct the links to `libstdc++' in general
-# (on some systems this causes no problem, but on others it doesn't!).
-#
-# However, to build a Static PatchELF, we need to be able to link with the
-# static C library, which is not always available on some GNU/Linux
-# systems. Therefore we need to check this here. If we can't build a static
-# PatchELF, we won't build any GCC either.
-if [ x"$host_cc" = x0 ]; then
-    testprog=$tmpblddir/test-c
-    testsource=$tmpblddir/test.c
-    echo; echo; echo "Checking if static C library is available...";
-    cat > $testsource <<EOF
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/cdefs.h>
-int main(void){printf("...yes\n");
-               return EXIT_SUCCESS;}
-EOF
-    cc_call="$CC $testsource $CPPFLAGS $LDFLAGS -o$testprog -static -lc"
-    if $cc_call && $testprog; then
-        gccwarning=0
-        good_static_libc=1
-        rm $testsource $testprog
-    else
-        echo; echo "Compilation command:"; echo "$cc_call"
-        good_static_libc=0
-        rm $testsource
-        gccwarning=1
-        host_cc=1
-        cat <<EOF
-
-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-!!!!!!!!!!!!!!!!!!!!!!         Warning        !!!!!!!!!!!!!!!!!!!!!!
-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
-The 'sys/cdefs.h' header cannot be included, or a usable static C library
-('libc.a', in any directory) cannot be used with the current settings of
-this system. SEE THE ERROR MESSAGE ABOVE.
-
-Because of this, we can't build GCC. You either 1) don't have them, or 2)
-the default system environment aren't enough to find them.
-
-1) If you don't have them, your operating system provides them as separate
-packages that you must manually install. Please look into your operating
-system documentation or contact someone familiar with it. For example on
-some Redhat-based GNU/Linux distributions, the static C library package can
-be installed with this command:
-
-    $ sudo yum install glibc-static
-
-2) If you have 'libc.a' and 'sys/cdefs.h', but in a non-standard location (for
-example in '/PATH/TO/STATIC/LIBC/libc.a' and
-'/PATH/TO/SYS/CDEFS_H/sys/cdefs.h'), please run the commands below, then
-re-configure the project to fix this problem.
-
-    $ export LDFLAGS="-L/PATH/TO/STATIC/LIBC \$LDFLAGS"
-    $ export CPPFLAGS="-I/PATH/TO/SYS/CDEFS_H \$LDFLAGS"
-
-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
-EOF
-    fi
-fi
-
-# Print a warning if GCC is not meant to be built.
-if [ x"$gccwarning" = x1 ]; then
-        cat <<EOF
-
-PLEASE SEE THE WARNINGS ABOVE.
-
-Since GCC is pretty low-level, this configuration script will continue in 5
-seconds and use your system's C compiler (it won't build a custom GCC). But
-please consider installing the necessary package(s) to complete your C
-compiler, then re-run './project configure'.
-
-EOF
-        sleep 5
-fi
-
-
-
-
-
-# Fortran compiler
-# ----------------
-#
-# If GCC is ultimately build within the project, the user won't need to
-# have a fortran compiler, we'll build it internally for high-level
-# programs. However, when the host C compiler is to be used, the user needs
-# to have a Fortran compiler available.
-if [ $host_cc = 1 ]; then
-
-    # See if a Fortran compiler exists.
-    hasfc=0;
-    if type gfortran > /dev/null 2>/dev/null; then hasfc=1; fi
-    if [ $hasfc = 0 ]; then
-        cat <<EOF
-______________________________________________________
-!!!!!!!      Fortran Compiler NOT FOUND        !!!!!!!
-
-Because the project won't be building its own GCC (which includes a Fortran
-compiler), you need to have a Fortran compiler available. Fortran is
-commonly necessary for many lower-level scientific programs. Currently we
-search for 'gfortran'. If you have a Fortran compiler that is not checked,
-please get in touch with us (with the form below) so we add it:
-
-  https://savannah.nongnu.org/support/?func=additem&group=reproduce
-
-Note: GCC will not be built because you are either using the '--host-cc'
-option, or you are using an operating system that currently has bugs when
-building GCC.
-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
-EOF
-        exit 1
-    fi
-
-    # See if the Fortran compiler works
-    testprog=$tmpblddir/test-f
-    testsource=$tmpblddir/test.f
-    echo; echo; echo "Checking host Fortran compiler...";
-    echo "      PRINT *, \"... Fortran Compiler works.\"" > $testsource
-    echo "      END"                                      >> $testsource
-    if gfortran $testsource -o$testprog && $testprog; then
-        rm $testsource $testprog
-    else
-        rm $testsource
-        cat <<EOF
-
-______________________________________________________
-!!!!!!!     Fortran compiler doesn't work      !!!!!!!
-
-Host Fortran compiler ('gfortran') can't build a simple program.
-
-A working Fortran compiler is necessary for building some of the project's
-software.  Please use the error message above to find a good solution and
-re-run the project configuration.
-
-If you can't find a solution, please send the error message above to the
-link below and we'll try to help
-
-https://savannah.nongnu.org/support/?func=additem&group=reproduce
-
-TIP: Once you find the solution, you can use the '-e' option to use
-existing configuration:
-
-   $ ./project configure -e
-
-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-
-EOF
-        exit 1
-    fi
-fi
-
-
-
-
-
 # inform the user that the build process is starting
 # -------------------------------------------------
 if [ $printnotice = yes ]; then
@@ -1185,7 +1164,6 @@ fi
 # some system specific locations like `/usr/lib/ARCHITECTURE' that some
 # operating systems use. We thus need to tell the intermediate compiler
 # where its necessary libraries and headers are.
-export CPPFLAGS="$CPPFLAGS $sys_cppflags"
 if [ x"$sys_library_path" != x ]; then
     if [ x"$LIBRARY_PATH" = x ]; then
         export LIBRARY_PATH="$sys_library_path"
@@ -1193,9 +1171,9 @@ if [ x"$sys_library_path" != x ]; then
         export LIBRARY_PATH="$LIBRARY_PATH:$sys_library_path"
     fi
     if [ x"$CPATH" = x ]; then
-        export LIBRARY_PATH="$sys_cpath"
+        export CPATH="$sys_cpath"
     else
-        export LIBRARY_PATH="$CPATH:$sys_cpath"
+        export CPATH="$CPATH:$sys_cpath"
     fi
 fi
 
@@ -1243,6 +1221,7 @@ fi
                     static_build=$static_build \
                     numthreads=$numthreads \
                     on_mac_os=$on_mac_os \
+                    sys_cpath=$sys_cpath \
                     host_cc=$host_cc \
                     -j$numthreads
 
diff --git a/reproduce/software/config/installation/LOCAL.conf.in b/reproduce/software/config/installation/LOCAL.conf.in
index 1045f72..0579218 100644
--- a/reproduce/software/config/installation/LOCAL.conf.in
+++ b/reproduce/software/config/installation/LOCAL.conf.in
@@ -12,5 +12,6 @@
 BDIR             = @bdir@
 INDIR            = @indir@
 DEPENDENCIES-DIR = @ddir@
+SYS_CPATH        = @sys_cpath@
 DOWNLOADER       = @downloader@
 GROUP-NAME       = @groupname@
diff --git a/reproduce/software/make/high-level.mk b/reproduce/software/make/high-level.mk
index 0d05626..02ae1a5 100644
--- a/reproduce/software/make/high-level.mk
+++ b/reproduce/software/make/high-level.mk
@@ -70,8 +70,8 @@ all: $(foreach p, $(top-level-programs),  $(ibidir)/$(p)) \
 .SHELLFLAGS := --noprofile --norc -ec
 export CCACHE_DISABLE := 1
 export PATH := $(ibdir)
-export CXX := $(ibdir)/g++
 export CC := $(ibdir)/gcc
+export CXX := $(ibdir)/g++
 export SHELL := $(ibdir)/bash
 export F77 := $(ibdir)/gfortran
 export LD_RUN_PATH := $(ildir):$(il64dir)
@@ -79,6 +79,11 @@ export PKG_CONFIG_PATH := $(ildir)/pkgconfig
 export LD_LIBRARY_PATH := $(ildir):$(il64dir)
 export PKG_CONFIG_LIBDIR := $(ildir)/pkgconfig
 
+# Until we build our own C library, without this, our GCC won't be able to
+# compile anything! Note that on most systems (in particular
+# non-Debian-based), `sys_cpath' will be empty.
+export CPATH := $(sys_cpath)
+
 # RPATH is automatically written in macOS, so `DYLD_LIBRARY_PATH' is
 # ultimately redundant. But on some systems, even having a single value
 # causes crashs (see bug #56682). So we'll just give it no value at all.