arm: Make 'conflicting CPU architectures' error message more user-friendly

Error messages such as "conflicting CPU architectures 10/16" are not
very to understand, so this patch replaces the numbers with the
description they actually mean:
"conflicting CPU architectures ARM v7E-M vs Pre v4"

2023-09-01  Christophe Lyon  <[email protected]>

	bfd/
	* elf32-arm.c (tag_cpu_arch_combine): Add name_table parameter and
	use it.
	(elf32_arm_merge_eabi_attributes): Update call to
	tag_cpu_arch_combine.

	ld/
	* testsuite/ld-arm/attr-merge-9.out: Update expected error
	message.
	* testsuite/ld-arm/attr-merge-arch-2.d: Likewise.

Author: Christophe Lyon

bfd/elf32-arm.c

@@ -14119,7 +14119,7 @@ set_secondary_compatible_arch (bfd *abfd, int arch)
 
 static int
 tag_cpu_arch_combine (bfd *ibfd, int oldtag, int *secondary_compat_out,
-		      int newtag, int secondary_compat)
+		      int newtag, int secondary_compat, const char* name_table[])
 {
 #define T(X) TAG_CPU_ARCH_##X
   int tagl, tagh, result;
@@ -14436,8 +14436,8 @@ tag_cpu_arch_combine (bfd *ibfd, int oldtag, int *secondary_compat_out,
 
   if (result == -1)
     {
-      _bfd_error_handler (_("error: %pB: conflicting CPU architectures %d/%d"),
-			  ibfd, oldtag, newtag);
+      _bfd_error_handler (_("error: conflicting CPU architectures %s vs %s in %pB"),
+			  name_table[oldtag], name_table[newtag], ibfd);
       return -1;
     }
 
@@ -14632,7 +14632,8 @@ elf32_arm_merge_eabi_attributes (bfd *ibfd, struct bfd_link_info *info)
 	    arch_attr = tag_cpu_arch_combine (ibfd, out_attr[i].i,
 					      &secondary_compat_out,
 					      in_attr[i].i,
-					      secondary_compat);
+					      secondary_compat,
+					      name_table);
 
 	    /* Return with error if failed to merge.  */
 	    if (arch_attr == -1)

ld/testsuite/ld-arm/attr-merge-9.out

@@ -1,2 +1,2 @@
-.*: error: .*: conflicting CPU architectures 10/16
+.*: error: conflicting CPU architectures ARM v7 vs ARM v8-M.baseline in .*
 .*: failed to merge target specific data of file tmpdir/attr-merge-9b.o

ld/testsuite/ld-arm/attr-merge-arch-2.d

@@ -2,4 +2,4 @@
 #source: attr-merge-arch-2b.s
 #as:
 #ld: -e main
-#error: conflicting CPU architectures 13/0
+#error: conflicting CPU architectures ARM v7E-M vs Pre v4 in .*