On 09/15/2015 10:52 AM, Marek Polacek wrote:
Currently, when one writes a code that is missing the struct/union/enum
tag, we get less than ideal error message. The following patch improves
the situation a bit by giving a hint to the user.
I can't count the number of times I've made this mistake and
scratched my head wondering what I did wrong. This is going
to help a lot!
FWIW, I would like it even more if there was just one message
instead of an error and a note. Since (when) the type is known,
could the error simply say:
error_at (here, "must use the %<struct%> keyword to refer to type %qE",
name);
Martin
I couldn't use lookup_tag as that gives the "defined as wrong kind of tag"
error; instead I wrote a new predicate.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2015-09-15 Marek Polacek <pola...@redhat.com>
PR c/67580
* c-decl.c (tag_exists_p): New function.
* c-parser.c (c_parser_declaration_or_fndef): Give a hint when
struct/union/enum keywords are missing.
* c-tree.h (tag_exists_p): Declare.
* gcc.dg/pr67580.c: New test.
diff --git gcc/c/c-decl.c gcc/c/c-decl.c
index 989ff99..a110226 100644
--- gcc/c/c-decl.c
+++ gcc/c/c-decl.c
@@ -3856,6 +3856,18 @@ lookup_tag (enum tree_code code, tree name, bool
thislevel_only,
return b->decl;
}
+/* Return true if a definition exists for NAME with code CODE. */
+
+bool
+tag_exists_p (enum tree_code code, tree name)
+{
+ struct c_binding *b = I_TAG_BINDING (name);
+
+ if (b == NULL || b->decl == NULL_TREE)
+ return false;
+ return TREE_CODE (b->decl) == code;
+}
+
/* Print an error message now
for a recent invalid struct, union or enum cross reference.
We don't print them immediately because they are not invalid
diff --git gcc/c/c-parser.c gcc/c/c-parser.c
index 4d9cbe0..d5de102 100644
--- gcc/c/c-parser.c
+++ gcc/c/c-parser.c
@@ -1539,8 +1539,16 @@ c_parser_declaration_or_fndef (c_parser *parser, bool
fndef_ok,
|| c_parser_peek_2nd_token (parser)->type == CPP_MULT)
&& (!nested || !lookup_name (c_parser_peek_token (parser)->value)))
{
- error_at (here, "unknown type name %qE",
- c_parser_peek_token (parser)->value);
+ tree name = c_parser_peek_token (parser)->value;
+ error_at (here, "unknown type name %qE", name);
+ /* Give a hint to the user. This is not C++ with its implicit
+ typedef. */
+ if (tag_exists_p (RECORD_TYPE, name))
+ inform (here, "use %<struct%> keyword to refer to the type");
+ else if (tag_exists_p (UNION_TYPE, name))
+ inform (here, "use %<union%> keyword to refer to the type");
+ else if (tag_exists_p (ENUMERAL_TYPE, name))
+ inform (here, "use %<enum%> keyword to refer to the type");
/* Parse declspecs normally to get a correct pointer type, but avoid
a further "fails to be a type name" error. Refuse nested functions
diff --git gcc/c/c-tree.h gcc/c/c-tree.h
index a3979dd..667529a 100644
--- gcc/c/c-tree.h
+++ gcc/c/c-tree.h
@@ -701,6 +701,7 @@ extern tree c_omp_reduction_lookup (tree, tree);
extern tree c_check_omp_declare_reduction_r (tree *, int *, void *);
extern void c_pushtag (location_t, tree, tree);
extern void c_bind (location_t, tree, bool);
+extern bool tag_exists_p (enum tree_code, tree);
/* In c-errors.c */
extern void pedwarn_c90 (location_t, int opt, const char *, ...)
diff --git gcc/testsuite/gcc.dg/pr67580.c gcc/testsuite/gcc.dg/pr67580.c
index e69de29..90e4b1b 100644
--- gcc/testsuite/gcc.dg/pr67580.c
+++ gcc/testsuite/gcc.dg/pr67580.c
@@ -0,0 +1,31 @@
+/* PR c/67580 */
+/* { dg-do compile } */
+
+struct S { int s; };
+union U { int s; };
+enum E { A };
+
+void
+f (void)
+{
+ S s; /* { dg-error "unknown type name" } */
+/* { dg-message "use .struct. keyword to refer to the type" "" { target *-*-*
} 11 } */
+ U u; /* { dg-error "unknown type name" } */
+/* { dg-message "use .union. keyword to refer to the type" "" { target *-*-* }
13 } */
+ E e; /* { dg-error "unknown type name" } */
+/* { dg-message "use .enum. keyword to refer to the type" "" { target *-*-* }
15 } */
+}
+
+void
+g (void)
+{
+ struct T { int i; };
+ union V { int i; };
+ enum F { J };
+ T t; /* { dg-error "unknown type name" } */
+/* { dg-message "use .struct. keyword to refer to the type" "" { target *-*-*
} 25 } */
+ V v; /* { dg-error "unknown type name" } */
+/* { dg-message "use .union. keyword to refer to the type" "" { target *-*-* }
27 } */
+ F f; /* { dg-error "unknown type name" } */
+/* { dg-message "use .enum. keyword to refer to the type" "" { target *-*-* }
29 } */
+}
Marek
