[gcc r15-2733] libbacktrace: avoid -Wpointer-arith errors

[Ian Lance Taylor via Gcc-cvs]

https://gcc.gnu.org/g:3a51aaf5f4ccd3d2ed871727c16f9c6f9ed54e50

commit r15-2733-g3a51aaf5f4ccd3d2ed871727c16f9c6f9ed54e50
Author: Ian Lance Taylor <i...@golang.org>
Date:   Mon Aug 5 16:46:03 2024 -0700

    libbacktrace: avoid -Wpointer-arith errors
    
    Based on patch from Kirill Müller.
    
            * configure.ac (ACX_PROG_CC_WARNING_OPTS): Add -Wpointer-arith.
            * pecoff.c (coff_add): Cast void pointers.
            * xcoff.c (xcoff_add): Likewise.
            * configure: Regenerate.

Diff:
---
 libbacktrace/configure    | 3 ++-
 libbacktrace/configure.ac | 3 ++-
 libbacktrace/pecoff.c     | 7 ++++---
 libbacktrace/xcoff.c      | 4 +++-
 4 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/libbacktrace/configure b/libbacktrace/configure
index fe0bb2083eb1..db491a782349 100755
--- a/libbacktrace/configure
+++ b/libbacktrace/configure
@@ -12385,7 +12385,8 @@ save_CFLAGS="$CFLAGS"
 for real_option in -W -Wall -Wwrite-strings -Wstrict-prototypes \
                          -Wmissing-prototypes -Wold-style-definition \
                          -Wmissing-format-attribute -Wcast-qual \
-                         -Wno-attributes -Wno-unknown-attributes; do
+                         -Wno-attributes -Wno-unknown-attributes \
+                         -Wpointer-arith; do
   # Do the check with the no- prefix removed since gcc silently
   # accepts any -Wno-* option on purpose
   case $real_option in
diff --git a/libbacktrace/configure.ac b/libbacktrace/configure.ac
index bfd7f35d2d2b..69eb2023677a 100644
--- a/libbacktrace/configure.ac
+++ b/libbacktrace/configure.ac
@@ -145,7 +145,8 @@ AC_SUBST(EXTRA_FLAGS)
 ACX_PROG_CC_WARNING_OPTS([-W -Wall -Wwrite-strings -Wstrict-prototypes \
                          -Wmissing-prototypes -Wold-style-definition \
                          -Wmissing-format-attribute -Wcast-qual \
-                         -Wno-attributes -Wno-unknown-attributes],
+                         -Wno-attributes -Wno-unknown-attributes \
+                         -Wpointer-arith],
                          [WARN_FLAGS])
 
 AC_ARG_ENABLE([werror],
diff --git a/libbacktrace/pecoff.c b/libbacktrace/pecoff.c
index ccd5ccbce2ce..15a73ff0b2aa 100644
--- a/libbacktrace/pecoff.c
+++ b/libbacktrace/pecoff.c
@@ -704,7 +704,7 @@ coff_add (struct backtrace_state *state, int descriptor,
       magic_ok = memcmp (magic, "PE\0", 4) == 0;
       fhdr_off += 4;
 
-      memcpy (&fhdr, fhdr_view.data + 4, sizeof fhdr);
+      memcpy (&fhdr, (const unsigned char *) fhdr_view.data + 4, sizeof fhdr);
     }
   else
     {
@@ -738,7 +738,7 @@ coff_add (struct backtrace_state *state, int descriptor,
   sects_view_valid = 1;
   opt_hdr = (const b_coff_optional_header *) sects_view.data;
   sects = (const b_coff_section_header *)
-    (sects_view.data + fhdr.size_of_optional_header);
+    ((const unsigned char *) sects_view.data + fhdr.size_of_optional_header);
 
   is_64 = 0;
   memset (&image_base, 0, sizeof image_base);
@@ -781,7 +781,8 @@ coff_add (struct backtrace_state *state, int descriptor,
        goto fail;
       syms_view_valid = 1;
 
-      str_size = coff_read4 (syms_view.data + syms_size);
+      str_size = coff_read4 ((const unsigned char *) syms_view.data
+                            + syms_size);
 
       str_off = syms_off + syms_size;
 
diff --git a/libbacktrace/xcoff.c b/libbacktrace/xcoff.c
index 01443c48401b..84ce07b8e2ca 100644
--- a/libbacktrace/xcoff.c
+++ b/libbacktrace/xcoff.c
@@ -1203,7 +1203,9 @@ xcoff_add (struct backtrace_state *state, int descriptor, 
off_t offset,
        goto fail;
       syms_view_valid = 1;
 
-      memcpy (&str_size, syms_view.data + syms_size, 4);
+      memcpy (&str_size,
+             (const unsigned char *) syms_view.data + syms_size,
+             4);
 
       str_off = fhdr.f_symptr + syms_size;