PR fortran/95090 - ICE: identifier overflow

The initial fix for this PR uncovered several latent issues with further
too small string buffers which showed up only when testing on i686.
Provide sufficiently large temporaries.

2020-05-29  Harald Anlauf  <anlauf@gmx.de>

gcc/fortran/
	PR fortran/95090
	* class.c (get_unique_type_string): Enlarge temporary for
	name-mangling.  Use strncpy to prevent buffer overrun.
	(get_unique_hashed_string): Enlarge temporary.
	(gfc_hash_value): Enlarge temporary for name-mangling.

(cherry picked from commit 7deca8c0b3765787627b11387b56b97b01a8bf33)

gcc/fortran/class.c

@@ -479,11 +479,12 @@ gfc_class_initializer (gfc_typespec *ts, gfc_expr *init_expr)
 static void
 get_unique_type_string (char *string, gfc_symbol *derived)
 {
-  char dt_name[GFC_MAX_SYMBOL_LEN+1];
+  /* Provide sufficient space to hold "Pdtsymbol".  */
+  char dt_name[GFC_MAX_SYMBOL_LEN+4];
   if (derived->attr.unlimited_polymorphic)
     strcpy (dt_name, "STAR");
   else
-    strcpy (dt_name, gfc_dt_upper_string (derived->name));
+    strncpy (dt_name, gfc_dt_upper_string (derived->name), sizeof (dt_name));
   if (derived->attr.unlimited_polymorphic)
     sprintf (string, "_%s", dt_name);
   else if (derived->module)
@@ -501,7 +502,8 @@ get_unique_type_string (char *string, gfc_symbol *derived)
 static void
 get_unique_hashed_string (char *string, gfc_symbol *derived)
 {
-  char tmp[2*GFC_MAX_SYMBOL_LEN+2];
+  /* Provide sufficient space to hold "symbol_Pdtsymbol".  */
+  char tmp[2*GFC_MAX_SYMBOL_LEN+5];
   get_unique_type_string (&tmp[0], derived);
   /* If string is too long, use hash value in hex representation (allow for
      extra decoration, cf. gfc_build_class_symbol & gfc_find_derived_vtab).
@@ -523,7 +525,8 @@ unsigned int
 gfc_hash_value (gfc_symbol *sym)
 {
   unsigned int hash = 0;
-  char c[2*(GFC_MAX_SYMBOL_LEN+1)];
+  /* Provide sufficient space to hold "symbol_Pdtsymbol".  */
+  char c[2*GFC_MAX_SYMBOL_LEN+5];
   int i, len;
 
   get_unique_type_string (&c[0], sym);