PR c++/92215 - flawed diagnostic for bit-field with non-integral type.

I noticed that for code like

  struct S {
    int *foo : 3;
  };

we generate nonsensical

  r.C:2:8: error: function definition does not declare parameters
      2 |   int *foo : 3;

It talks about a function because after parsing the declspecs of 'foo' we don't
see either ':' or "name :", so we think it's not a bit-field decl.  So we parse
the declarator and since a ctor-initializer begins with a ':', we try to parse
it as a function body, generating the awful diagnostic.  With this patch, we
issue:

  r.C:2:8: error: bit-field ‘foo’ has non-integral type ‘int*’
      2 |   int *foo : 3;

	* parser.c (cp_parser_member_declaration): Add a diagnostic for
	bit-fields with non-integral types.

	* g++.dg/diagnostic/bitfld4.C: New test.

From-SVN: r277991

gcc/cp/ChangeLog

+2019-11-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/92215 - flawed diagnostic for bit-field with non-integral type.
+	* parser.c (cp_parser_member_declaration): Add a diagnostic for
+	bit-fields with non-integral types.
+
 2019-11-08  Jakub Jelinek  <jakub@redhat.com>
 
 	* init.c (build_vec_delete_1): Fix a comment typo - mist -> must.

gcc/cp/parser.c

@@ -25037,6 +25037,31 @@ cp_parser_member_declaration (cp_parser* parser)
 		  else
 		    initializer = cp_parser_initializer (parser, &x, &x);
 		}
+	      /* Detect invalid bit-field cases such as
+
+		   int *p : 4;
+		   int &&r : 3;
+
+		 and similar.  */
+	      else if (cp_lexer_next_token_is (parser->lexer, CPP_COLON)
+		       /* If there were no type specifiers, it was a
+			  constructor.  */
+		       && decl_specifiers.any_type_specifiers_p)
+		{
+		  /* This is called for a decent diagnostic only.  */
+		  tree d = grokdeclarator (declarator, &decl_specifiers,
+					   BITFIELD, /*initialized=*/false,
+					   &attributes);
+		  error_at (DECL_SOURCE_LOCATION (d),
+			    "bit-field %qD has non-integral type %qT",
+			    d, TREE_TYPE (d));
+		  cp_parser_skip_to_end_of_statement (parser);
+		  /* Avoid "extra ;" pedwarns.  */
+		  if (cp_lexer_next_token_is (parser->lexer,
+					      CPP_SEMICOLON))
+		    cp_lexer_consume_token (parser->lexer);
+		  goto out;
+		}
 	      /* Otherwise, there is no initializer.  */
 	      else
 		initializer = NULL_TREE;

gcc/testsuite/ChangeLog

 2019-11-08  Marek Polacek  <polacek@redhat.com>
 
+	PR c++/92215 - flawed diagnostic for bit-field with non-integral type.
+	* g++.dg/diagnostic/bitfld4.C: New test.
+
+2019-11-08  Marek Polacek  <polacek@redhat.com>
+
 	PR c++/92058 - constinit malfunction in static data member.
 	* g++.dg/cpp2a/constinit15.C: New test.
 

gcc/testsuite/g++.dg/diagnostic/bitfld4.C

+// PR c++/92215 - flawed diagnostic for bit-field with non-integral type.
+// { dg-do compile { target c++11 } }
+
+struct S {
+  int *f1 : 3; // { dg-error "bit-field .f1. has non-integral type .int\\*." }
+  int &f2 : 3; // { dg-error "bit-field .f2. has non-integral type .int&." }
+  int &&f3 : 3; // { dg-error "bit-field .f3. has non-integral type .int&&." }
+  int f4[1] : 3; // { dg-error "bit-field .f4. has non-integral type .int \\\[1\\\]." }
+  int *f5 __attribute__((deprecated)) : 3; // { dg-error "bit-field .f5. has non-integral type .int\\*." }
+  int f6[1] __attribute__((deprecated)) : 3; // { dg-error "bit-field .f6. has non-integral type .int \\\[1\\\]." }
+  int &f7 __attribute__((deprecated)): 3; // { dg-error "bit-field .f7. has non-integral type .int&." }
+  int ****: 3; // { dg-error "expected" }
+  int *f9[1] : 3; // { dg-error "bit-field .f9. has non-integral type .int\\* \\\[1\\\]." }
+  int (*f10)() : 3; // { dg-error "bit-field .f10. has non-integral type .int \\(\\*\\)\\(\\)." }
+  int [][2] : 3; // { dg-error "expected" }
+};