[gcc r13-2932] driver, cppdefault: Unbreak bootstrap on Debian/Ubuntu [PR107059]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:a5a9237e2a78a9854f1f87e63ef5619cf8ba7360

commit r13-2932-ga5a9237e2a78a9854f1f87e63ef5619cf8ba7360
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Sep 29 12:04:24 2022 +0200

    driver, cppdefault: Unbreak bootstrap on Debian/Ubuntu [PR107059]
    
    My recent change to enable _Float{16,32,64,128,32x,64x,128x} for C++
    apparently broke bootstrap on some Debian/Ubuntu setups.
    Those multiarch targets put some headers into
    /usr/include/x86_64-linux-gnu/bits/ etc. subdirectory instead of
    /usr/include/bits/.
    This is handled by
        /* /usr/include comes dead last.  */
        { NATIVE_SYSTEM_HEADER_DIR, NATIVE_SYSTEM_HEADER_COMPONENT, 0, 0, 1, 2 },
        { NATIVE_SYSTEM_HEADER_DIR, NATIVE_SYSTEM_HEADER_COMPONENT, 0, 0, 1, 0 },
    in cppdefault.cc, where the 2 in the last element of the first initializer
    means the entry is ignored on non-multiarch and suffixed by the multiarch
    dir otherwise, so installed gcc has search path like:
     /home/jakub/gcc/obj01inst/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.0.0/include
     /home/jakub/gcc/obj01inst/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.0.0/include-fixed
     /usr/local/include
     /usr/include/x86_64-linux-gnu
     /usr/include
    (when installed with DESTDIR=/home/jakub/gcc/obj01inst).
    Now, when fixincludes is run, it is processing the whole /usr/include dir
    and all its subdirectories, so floatn{,-common.h} actually go into
    .../include-fixed/x86_64-linux-gnu/bits/floatn{,-common.h}
    because that is where they appear in /usr/include too.
    In some setups, /usr/include also contains /usr/include/bits -> x86_64-linux-gnu/bits
    symlink and after the r13-2896 tweak it works.
    In other setups there is no /usr/include/bits symlink and when one
     #include <bits/floatn.h>
    given the above search path, it doesn't find the fixincluded header,
    as
    /home/jakub/gcc/obj01inst/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.0.0/include-fixed/bits/floatn.h
    doesn't exist and
    /home/jakub/gcc/obj01inst/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.0.0/include-fixed/x86_64-linux-gnu/bits/floatn.h
    isn't searched and so
    /usr/include/x86_64-linux-gnu/bits/floatn.h
    wins and we fail because of typedef whatever _Float128; and similar.
    The following patch ought to fix this.  The first hunk by arranging that
    the installed search path actually looks like:
     /home/jakub/gcc/obj01inst/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.0.0/include
     /home/jakub/gcc/obj01inst/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.0.0/include-fixed/x86_64-linux-gnu
     /home/jakub/gcc/obj01inst/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.0.0/include-fixed
     /usr/local/include
     /usr/include/x86_64-linux-gnu
     /usr/include
    and thus for include-fixed it treats it the same as /usr/include.
    The second FIXED_INCLUDE_DIR entry there is:
         { FIXED_INCLUDE_DIR, "GCC", 0, 0, 0,
           /* A multilib suffix needs adding if different multilibs use
              different headers.  */
     #ifdef SYSROOT_HEADERS_SUFFIX_SPEC
           1
     #else
           0
     #endif
         },
    where SYSROOT_HEADERS_SUFFIX_SPEC is defined only on vxworks or mips*-mti-linux
    and arranges for multilib path to be appended there.  Neither of those
    systems is multiarch.
    This isn't enough, because when using the -B option, the driver adds
    -isystem .../include-fixed in another place, so the second hunk modifies
    that spot the same.
    /home/jakub/gcc/obj01/gcc/xgcc -B /home/jakub/gcc/obj01/gcc/
    then has search path:
     /home/jakub/gcc/obj01/gcc/include
     /home/jakub/gcc/obj01/gcc/include-fixed/x86_64-linux-gnu
     /home/jakub/gcc/obj01/gcc/include-fixed
     /usr/local/include
     /usr/include/x86_64-linux-gnu
     /usr/include
    which again is what I think we want to achieve.
    
    2022-09-29  Jakub Jelinek  <jakub@redhat.com>
    
            PR bootstrap/107059
            * cppdefault.cc (cpp_include_defaults): If SYSROOT_HEADERS_SUFFIX_SPEC
            isn't defined, add FIXED_INCLUDE_DIR entry with multilib flag 2
            before FIXED_INCLUDE_DIR entry with multilib flag 0.
            * gcc.cc (do_spec_1): If multiarch_dir, add
            include-fixed/multiarch_dir paths before include-fixed paths.

Diff:
---
 gcc/cppdefault.cc |  3 +++
 gcc/gcc.cc        | 12 ++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/gcc/cppdefault.cc b/gcc/cppdefault.cc
index 7888300f277..7d8f9a53231 100644
--- a/gcc/cppdefault.cc
+++ b/gcc/cppdefault.cc
@@ -74,6 +74,9 @@ const struct default_include cpp_include_defaults[]
 #endif
 #ifdef FIXED_INCLUDE_DIR
     /* This is the dir for fixincludes.  */
+#ifndef SYSROOT_HEADERS_SUFFIX_SPEC
+    { FIXED_INCLUDE_DIR, "GCC", 0, 0, 0, 2 },
+#endif
     { FIXED_INCLUDE_DIR, "GCC", 0, 0, 0,
       /* A multilib suffix needs adding if different multilibs use
 	 different headers.  */
diff --git a/gcc/gcc.cc b/gcc/gcc.cc
index 2ffbbc0bf2a..afb23cd07b0 100644
--- a/gcc/gcc.cc
+++ b/gcc/gcc.cc
@@ -6415,6 +6415,18 @@ do_spec_1 (const char *spec, int inswitch, const char *soft_matched_part)
 	      if (*sysroot_hdrs_suffix_spec)
 		info.append = concat (info.append, dir_separator_str,
 				      multilib_dir, NULL);
+	      else if (multiarch_dir)
+		{
+		  /* For multiarch, search include-fixed/<multiarch-dir>
+		     before include-fixed.  */
+		  info.append = concat (info.append, dir_separator_str,
+					multiarch_dir, NULL);
+		  info.append_len = strlen (info.append);
+		  for_each_path (&include_prefixes, false, info.append_len,
+				 spec_path, &info);
+
+		  info.append = "include-fixed";
+		}
 	      info.append_len = strlen (info.append);
 	      for_each_path (&include_prefixes, false, info.append_len,
 			     spec_path, &info);