[Bug c++/88261] [9 Regression] ICE: verify_gimple failed (error: non-trivial conversion at assignment)

[edlinger at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88261

--- Comment #10 from Bernd Edlinger <edlinger at gcc dot gnu.org> ---
Hmm, there are a few loose ends, where there is simply no decl.
For instance in this example:

/* PR c/5597 */
/* { dg-do compile } */
/* { dg-options "" } */

/* Verify that GCC forbids non-static initialization of
   flexible array members. */

struct str { int len; char s[]; };

struct str a = { 2, "a" };

void foo()
{
  static struct str d = (struct str) { 2, "d" }; /* { dg-error
"(non-static)|(near initialization)" } */
  static struct str e = (struct str) { d.len, "e" }; /* { dg-error
"(non-static)|(initialization)" } */
}

$ g++ -S array-6.c
array-6.c:14:47: error: non-static initialization of a flexible array member
   14 |   static struct str d = (struct str) { 2, "d" }; /* { dg-error
"(non-static)|(near initialization)" } */
      |                                               ^
array-6.c:15:51: error: non-static initialization of a flexible array member
   15 |   static struct str e = (struct str) { d.len, "e" }; /* { dg-error
"(non-static)|(initialization)" } */
      |                                                   ^


the patch prints an error, but digest_init_r is called from
finish_compound_literal:
2830      compound_literal = digest_init_flags (type, compound_literal,
LOOKUP_NORMAL,
2831                                            complain, NULL_TREE);

So here it is impossible to tell which decl is going to be initialized,
because this is called drectly from the parser (cp_parser_postfix_expression).

However the C-FE does also not have a decl here, and I think I cannot do
much about that:

$ gcc -S array-6.c 
array-6.c: In function 'foo':
array-6.c:14:43: error: non-static initialization of a flexible array member
   14 |   static struct str d = (struct str) { 2, "d" }; /* { dg-error
"(non-static)|(near initialization)" } */
      |                                           ^~~
array-6.c:14:43: note: (near initialization for '(anonymous)')
array-6.c:15:47: error: non-static initialization of a flexible array member
   15 |   static struct str e = (struct str) { d.len, "e" }; /* { dg-error
"(non-static)|(initialization)" } */
      |                                               ^~~
array-6.c:15:47: note: (near initialization for '(anonymous)')
array-6.c:15:25: error: initializer element is not constant
   15 |   static struct str e = (struct str) { d.len, "e" }; /* { dg-error
"(non-static)|(initialization)" } */
      |                         ^