C: detect more missing semicolons (PR c/7356)

C: detect more missing semicolons (PR c/7356)

c_parser_declaration_or_fndef has logic for parsing what might be
either a declaration or a function definition.

This patch adds a test to detect cases where a semicolon would have
terminated the decls as a declaration, where the token that follows
would start a new declaration specifier, and updates the error message
accordingly, with a fix-it hint.

This addresses PR c/7356, fixing the case of a stray token before a
#include that previously gave inscrutable output, and improving e.g.:

  int i
  int j;

from:

  t.c:2:1: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'int'
   int j;
   ^~~

to:

  t.c:1:6: error: expected ';' before 'int'
   int i
        ^
        ;
   int j;
   ~~~

gcc.dg/noncompile/920923-1.c needs a slight update, as the output for
the first line changes from:

  920923-1.c:2:14: error: expected '=', ',', ';', 'asm' or
  '__attribute__' before 'unsigned'
   typedef BYTE unsigned char; /* { dg-error "expected" } */
                ^~~~~~~~

to:
  920923-1.c:2:13: error: expected ';' before 'unsigned'
   typedef BYTE unsigned char; /* { dg-error "expected" } */
               ^~~~~~~~~
               ;
  920923-1.c:2:1: warning: useless type name in empty declaration
   typedef BYTE unsigned char; /* { dg-error "expected" } */
   ^~~~~~~

The patch also adds a test for PR c/44515 as a baseline.

gcc/c/ChangeLog:
	PR c/7356
	* c-parser.c (c_parser_declaration_or_fndef): Detect missing
	semicolons.

gcc/testsuite/ChangeLog:
	PR c/7356
	PR c/44515
	* c-c++-common/pr44515.c: New test case.
	* gcc.dg/pr7356-2.c: New test case.
	* gcc.dg/pr7356.c: New test case.
	* gcc.dg/spellcheck-typenames.c: Update the "singed" char "TODO"
	case to reflect changes to output.
	* gcc.dg/noncompile/920923-1.c: Add dg-warning to reflect changes
	to output.

From-SVN: r254093