Hi!
handle_dll_attribute sets DECL_EXTERNAL on node for "dllimport" on
VAR_DECLs, it wants to handle those as if those vars are actually declared
extern. The problem is that it doesn't clear TREE_STATIC on them, which
is what is normally the case on VAR_DECLs that are DECL_EXTERNAL and so
the C FE that checks for incomplete structs and uses TREE_STATIC incorrectly
diagnoses that.
Joseph said in the PR that DECL_EXTERNAL + TREE_STATIC combination is for
gnu_inline extern inlines, where it indeed makes sense, there is an external
definition and a static alternative for that, but for the VAR_DECLs nothing
like that makes sense.
I have no idea under what maintainership this falls into, because it is
in middle-end code, but handle_dll_attribute seems to be very Windows
specific.
JonY said in the PR that testing went well.
Ok for trunk?
2019-01-10 Jakub Jelinek <ja...@redhat.com>
PR c/88568
* attribs.c (handle_dll_attribute): Clear TREE_STATIC after setting
DECL_EXTERNAL.
* gcc.dg/pr88568.c: New test.
--- gcc/attribs.c.jj 2019-01-05 12:06:12.055124090 +0100
+++ gcc/attribs.c 2019-01-07 12:57:09.739782281 +0100
@@ -1691,6 +1691,8 @@ handle_dll_attribute (tree * pnode, tree
a function global scope, unless declared static. */
if (current_function_decl != NULL_TREE && !TREE_STATIC (node))
TREE_PUBLIC (node) = 1;
+ /* Clear TREE_STATIC because DECL_EXTERNAL is set. */
+ TREE_STATIC (node) = 0;
}
if (*no_add_attrs == false)
--- gcc/testsuite/gcc.dg/pr88568.c.jj 2019-01-07 13:00:43.113279882 +0100
+++ gcc/testsuite/gcc.dg/pr88568.c 2019-01-07 13:00:16.494718463 +0100
@@ -0,0 +1,4 @@
+/* PR c/88568 */
+/* { dg-do compile } */
+/* { dg-require-dll "" } */
+__attribute__((dllimport)) struct S var; /* { dg-bogus "storage size of
.var. isn.t known" } */
Jakub
