Architecture-specific C headers on Debian-based OSs now accounted

Rencely the building of GCC was allowed on Debian-based systems that have
their basic C library in architecture-specific directories, like
`/usr/lib/x86_64-linux-gnu'. However, these systems also have their headers
in non-standard locations, for example `/usr/include/x86_64-linux-gnu' and
this caused a crash on a new Ubuntu system.

/usr/include/stdio.h:27:10: fatal error: bits/libc-header-start.h: No
such file or directory
   27 | #include <bits/libc-header-start.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.

The reason it didn't cause problems on other Ubuntus that we tested before
was historic: In the old days, we would ask Ubuntu systems to install
multilib features to have GCC. Because they had installed those features,
this problem didn't show up! But this wasn't mandatory!

With this commit, the `CPATH' environment variable is set (similar to how
`LIBRARY_PATH' was set) and this fixed the problem on a clean Debian
virtual machine.

This bug was reported by Sebastian Luna Valero.

1 files changed, 15 insertions, 6 deletions

diff --git a/reproduce/software/bash/configure.sh b/reproduce/software/bash/configure.sh
index a4b3e64..96c4ad0 100755
--- a/reproduce/software/bash/configure.sh
+++ b/reproduce/software/bash/configure.sh
@@ -872,13 +872,13 @@ if [ x"$$on_mac_os" != xyes ]; then
     if [ x"$gcctarget" != x ]; then
         if [ -f /usr/lib/$gcctarget/libc.a ]; then
             export sys_library_path=/usr/lib/$gcctarget
-            export sys_cppflags=-I/usr/include/$gcctarget
+            export sys_cpath=/usr/include/$gcctarget
         fi
     fi
 
     # For a check:
     #echo "sys_library_path: $sys_library_path"
-    #echo "sys_cppflags: $sys_cppflags"
+    #echo "sys_cpath: $sys_cpath"
 fi
 
 
@@ -1176,11 +1176,15 @@ fi
 
 
 
-# library_path (ONLY FOR BASIC)
-# -----------------------------
+# Paths needed by the host compiler (only for `basic.mk')
+# -------------------------------------------------------
 #
-# During the basic build, we need to include possibly existing special C
-# compiler targets (if they exist).
+# At the end of the basic build, we need to build GCC. But GCC will build
+# in multiple phases, making its own simple compiler in order to build
+# itself completely. The intermediate/simple compiler doesn't recognize
+# 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"$LIBRARY_PATH" = x ]; then
@@ -1188,6 +1192,11 @@ if [ x"$sys_library_path" != x ]; then
     else
         export LIBRARY_PATH="$LIBRARY_PATH:$sys_library_path"
     fi
+    if [ x"$CPATH" = x ]; then
+        export LIBRARY_PATH="$sys_cpath"
+    else
+        export LIBRARY_PATH="$CPATH:$sys_cpath"
+    fi
 fi