[patch,avr] PR81407: Error if progmem variable needs constructing.

[Georg-Johann Lay]

Hi, if the C++ front-end decides that something will need constructing,
it will silently put the stuff into .rodata so that according
pgm_read_xxx will read garbage from .progmem.

As proposed by Jason, this patch diagnoses such situations.

Ok to commit?

Johann

        PR target/81407
        * config/avr/avr.c (avr_encode_section_info)
        [progmem && !TREE_READONLY]: Error if progmem object needs
        constructing.

Index: config/avr/avr.c
===================================================================
--- config/avr/avr.c	(revision 250093)
+++ config/avr/avr.c	(working copy)
@@ -10380,14 +10380,22 @@ avr_encode_section_info (tree decl, rtx
       && !DECL_EXTERNAL (decl)
       && avr_progmem_p (decl, DECL_ATTRIBUTES (decl)))
     {
-      // Don't warn for (implicit) aliases like in PR80462.
       tree asmname = DECL_ASSEMBLER_NAME (decl);
       varpool_node *node = varpool_node::get_for_asmname (asmname);
       bool alias_p = node && node->alias;
 
-      if (!alias_p)
-        warning (OPT_Wuninitialized, "uninitialized variable %q+D put into "
-                 "program memory area", decl);
+      if (!TREE_READONLY (decl))
+        {
+          // This might happen with C++ if stuff needs constructing.
+          error ("variable %q+D with dynamic initialization put "
+                 "into program memory area", decl);
+        }
+      else if (!alias_p)
+        {
+          // Don't warn for (implicit) aliases like in PR80462.
+          warning (OPT_Wuninitialized, "uninitialized variable %q+D put "
+                   "into program memory area", decl);
+        }
     }
 
   default_encode_section_info (decl, rtl, new_decl_p);