Configure script prefers clang for macOS systems

In the previous commit (Commit 1bc00c9: Only using clang in macOS systems
that also have GCC) we set the used C compiler for high-level programs to
be 'clang' on macOS systems. But I forgot to do the same kind of change in
the configure script (to prefer 'clang' when we are testing for a C
compiler on the host).

With this commit, the compiler checking phases of the configure script have
been improved, so on macOS systems, we now first search for 'clang', then
search for 'gcc'.

While doing this, I also noticed that the 'rpath' checking command was done
before we actually define 'instdir'!!! So in effect, the 'rpath' directory
was being set to '/lib'! So with this commit, this test has been taken to
after defining 'instdir'.

2 files changed, 129 insertions, 96 deletions

diff --git a/reproduce/software/make/high-level.mk b/reproduce/software/make/high-level.mk
index 6e14b2d..3ac3b49 100644
--- a/reproduce/software/make/high-level.mk
+++ b/reproduce/software/make/high-level.mk
@@ -52,6 +52,7 @@ ildir   = $(BDIR)/software/installed/lib
 ibidir  = $(BDIR)/software/installed/version-info/proglib
 
 # Basic directories (specific to this Makefile).
+il64dir  = $(BDIR)/software/installed/lib64
 iidir    = $(BDIR)/software/installed/include
 shsrcdir = $(shell pwd)/reproduce/software/shell
 dtexdir  = $(shell pwd)/reproduce/software/bibtex
diff --git a/reproduce/software/shell/configure.sh b/reproduce/software/shell/configure.sh
index f428416..001b531 100755
--- a/reproduce/software/shell/configure.sh
+++ b/reproduce/software/shell/configure.sh
@@ -186,35 +186,93 @@ free_space_warning()
 
 
 
+# See if we are on a Linux-based system
+# --------------------------------------
+#
+# Some features are tailored to GNU/Linux systems, while the BSD-based
+# behavior is different. Initially we only tested macOS (hence the name of
+# the variable), but as FreeBSD is also being inlucded in our tests. As
+# more systems get used, we need to tailor these kinds of things better.
+kernelname=$(uname -s)
+if [ x$kernelname = xLinux ]; then
+    on_mac_os=no
+
+    # Don't forget to add the respective C++ compiler below (leave 'cc' in
+    # the end).
+    c_compiler_list="gcc clang cc"
+else
+    host_cc=1
+    on_mac_os=yes
+
+    # Don't forget to add the respective C++ compiler below (leave 'cc' in
+    # the end).
+    c_compiler_list="clang gcc cc"
+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
+# To build the software, we'll need some basic tools (the C/C++ compilers
+# in particular) to be present.
+has_compilers=no
+for c in $c_compiler_list; do
+
+    # Set the respective C++ compiler.
+    if   [ x$c = xcc    ]; then cplus=c++;
+    elif [ x$c = xgcc   ]; then cplus=g++;
+    elif [ x$c = xclang ]; then cplus=clang++;
     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
+        cat <<EOF
+______________________________________________________
+!!!!!!!                   BUG                  !!!!!!!
+
+The respective C++ compiler executable name for the C compiler '$c' hasn't
+been set! You can add it in the 'reproduce/software/shell/configure.sh'
+script (just above this error message), or contact us with this web-form:
+
+    https://savannah.nongnu.org/support/?func=additem&group=reproduce
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+EOF
+        exit 1
+    fi
+
+    # Check if they exist.
+    if type $c > /dev/null 2>/dev/null; then
+        export CC=$c;
+        if type $cplus > /dev/null 2>/dev/null; then
+            export CXX=$cplus
+            has_compilers=yes
+            break
         fi
     fi
-fi
-if [ $hascc = 0 ]; then
+done
+if [ x$has_compilers = xno ]; 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:
+To build this project's software, the host system needs to have both C and
+C++ compilers. The commands that were checked are listed below:
+
+    cc, c++            Generic C/C++ compiler (possibly links to below).
+    gcc, g++           Part of GNU Compiler Collection (GCC).
+    clang, clang++     Part of LLVM compiler infrastructure.
+
+If your compiler is not checked, please get in touch with the web-form
+below, so we add it. We will try our best to add it soon. Until then,
+please install at least one of these compilers on your system to proceed.
+
+    https://savannah.nongnu.org/support/?func=additem&group=reproduce
+
+NOTE: for macOS systems, the LLVM compilers that are provided in a native
+Xcode install are recommended. There are known problems with GCC on macOS.
 
-  https://savannah.nongnu.org/support/?func=additem&group=reproduce
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
 EOF
@@ -238,10 +296,9 @@ 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...";
+echo; echo; echo "Checking host C compiler ('$CC')...";
 cat > $testsource <<EOF
 #include <stdio.h>
 #include <stdlib.h>
@@ -257,7 +314,7 @@ else
 ______________________________________________________
 !!!!!!!        C compiler doesn't work         !!!!!!!
 
-Host C compiler ('gcc') can't build a simple program.
+Host C compiler ('$CC') 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
@@ -268,11 +325,6 @@ 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
@@ -283,28 +335,6 @@ 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)
 # ----------------------------------------
 #
@@ -326,7 +356,7 @@ if $CC $testsource -o$testprog 2>/dev/null > /dev/null; then
 else
     needs_ldl=yes;
 fi
-rm -f $testprog $testsource
+
 
 
 
@@ -351,25 +381,6 @@ static_build=no
 
 
 
-# See if we are on a Linux-based system
-# --------------------------------------
-#
-# Some features are tailored to GNU/Linux systems, while the BSD-based
-# behavior is different. Initially we only tested macOS (hence the name of
-# the variable), but as FreeBSD is also being inlucded in our tests. As
-# more systems get used, we need to tailor these kinds of things better.
-kernelname=$(uname -s)
-if [ x$kernelname = xLinux ]; then
-    on_mac_os=no
-else
-    host_cc=1
-    on_mac_os=yes
-fi
-
-
-
-
-
 # Print warning if the host CC is to be used.
 if [ x$host_cc = x1 ]; then
     cat <<EOF
@@ -521,19 +532,19 @@ ______________________________________________________
 !!!!!!!      Fortran Compiler NOT FOUND        !!!!!!!
 
 The project won't be building its own GCC (which includes a Fortran
-compiler) on this system. If you need software that need a Fortran
-compiler, it will crash with an error. Fortran is necessary for many
-lower-level scientific programs, hence this warning. 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:
+compiler) on this system. If the project needs software that require a
+Fortran compiler, they will crash with a error. Fortran is necessary in
+some lower-level scientific programs (hence this warning!). 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
 
-Project's configuration will continue in 5 seconds.
+Project's configuration will continue in 2 seconds.
 ______________________________________________________
 
 EOF
-        sleep 5
+        sleep 2
     else
 
         # See if the Fortran compiler works
@@ -552,25 +563,20 @@ ______________________________________________________
 
 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.
+A working Fortran compiler is necessary for building some software (which
+may not be necessary for this project!). 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
-
-Project's configuration will continue in 5 seconds.
+Project's configuration will continue in 2 seconds.
 ______________________________________________________
 
 EOF
-            sleep 5
+            sleep 2
         fi
     fi
 fi
@@ -579,17 +585,6 @@ 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
 # ---------------
 #
@@ -1254,6 +1249,43 @@ 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.
+#
+# IMPORTANT NOTE: This test has to be done **AFTER** the definition of
+# 'instdir', otherwise, it is going to be used as an empty string.
+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
+
+
+
+
+
+# Delete the compiler testing directory
+# -------------------------------------
+#
+# This directory was made above to make sure the necessary compilers can be
+# run.
+rm -f $testprog $testsource
+rm -rf $compilertestdir
+
+
+
+
+
 # Paths needed by the host compiler (only for `basic.mk')
 # -------------------------------------------------------
 #