Fix type mismatches with incomplete types

If I put the following in a public header:

   struct foo;
   typedef struct foo *Foo;

   void func (Foo f);

and the definition of struct foo in a private header:

   struct foo { int bar; }

then I get a sparse warning (different base type for argument 1) when
I compile the implementation file:

   #include "public.h"
   #include "private.h"

   void func (Foo f) { ... }

i.e. sparse doesn't realise that the incomplete structure definition
in the function  prototype refers to the same type as the complete
structure definition in the function definition.

*I think* that the patch fixes this - it silences the error - but I
don't know enough about sparse to know whether it's correct (or
whether it silences other legitimate errors, for example).

Signed-off-by: Geoff Johnstone <geoff.johnstone@googlemail.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/evaluate.c b/evaluate.c
index 49285841..2a126ddb 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -697,8 +697,12 @@ const char *type_difference(struct ctype *c1, struct ctype *c2,
 				     type);
 			return "bad types";
 		case SYM_RESTRICT:
+			return "different base types";
 		case SYM_UNION:
 		case SYM_STRUCT:
+			/* allow definition of incomplete structs and unions */
+			if (t1->ident == t2->ident)
+			  return NULL;
 			return "different base types";
 		case SYM_ARRAY:
 			/* XXX: we ought to compare sizes */