cp-demangle.c (cplus_demangle_print_callback): Avoid zero-length VLAs.

2016-06-12  Brooks Moses  <bmoses@google.com>

	* cp-demangle.c (cplus_demangle_print_callback): Avoid zero-length
	  VLAs.

From-SVN: r238233

libiberty/ChangeLog

+2016-06-12  Brooks Moses  <bmoses@google.com>
+
+	* cp-demangle.c (cplus_demangle_print_callback): Avoid zero-length
+	  VLAs.
+
 2016-05-31  Alan Modra  <amodra@gmail.com>
 
 	* xmemdup.c (xmemdup): Use xmalloc rather than xcalloc.

libiberty/cp-demangle.c

@@ -4128,8 +4128,12 @@ cplus_demangle_print_callback (int options,
 
   {
 #ifdef CP_DYNAMIC_ARRAYS
-    __extension__ struct d_saved_scope scopes[dpi.num_saved_scopes];
-    __extension__ struct d_print_template temps[dpi.num_copy_templates];
+    /* Avoid zero-length VLAs, which are prohibited by the C99 standard
+       and flagged as errors by Address Sanitizer.  */
+    __extension__ struct d_saved_scope scopes[(dpi.num_saved_scopes > 0)
+                                              ? dpi.num_saved_scopes : 1];
+    __extension__ struct d_print_template temps[(dpi.num_copy_templates > 0)
+                                                ? dpi.num_copy_templates : 1];
 
     dpi.saved_scopes = scopes;
     dpi.copy_templates = temps;