One failure with a -std=gnu23 default that indicates a
quality-of-implementation regression in C23 mode is gcc.dg/pr39084.c,
which loses the expected "originally defined here" message on struct
redefinition errors (which occur in a different place in the front end
for C23 because it is necessary to see the members of the struct to
determine whether the redefinition is valid). That message seems a
good thing to have both in and out of C23 mode, so add logic to
restore it in the C23 case.
Bootstrapped with no regressions for x86-64-pc-linux-gnu.
gcc/c/
* c-decl.cc (c_struct_parse_info): Add member refloc.
(start_struct): Store refloc in struct_parse_info.
(finish_struct): Give "originally defined" message for C23 struct
redefinition errors.
gcc/testsuite/
* gcc.dg/gnu17-tag-1.c, gcc.dg/gnu23-tag-5.c: New tests.
diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index 3733ecfc13f..047158eef9d 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -640,6 +640,8 @@ public:
/* If warn_cxx_compat, a list of typedef names used when defining
fields in this struct. */
auto_vec<tree> typedefs_seen;
+ /* The location of a previous definition of this struct. */
+ location_t refloc;
};
@@ -9000,6 +9002,7 @@ start_struct (location_t loc, enum tree_code code, tree
name,
*enclosing_struct_parse_info = struct_parse_info;
struct_parse_info = new c_struct_parse_info ();
+ struct_parse_info->refloc = refloc;
/* FIXME: This will issue a warning for a use of a type defined
within a statement expr used within sizeof, et. al. This is not
@@ -9896,10 +9899,18 @@ finish_struct (location_t loc, tree t, tree fieldlist,
tree attributes,
{
TYPE_STUB_DECL (vistype) = TYPE_STUB_DECL (t);
if (c_type_variably_modified_p (t))
- error ("redefinition of struct or union %qT with variably "
- "modified type", t);
+ {
+ error ("redefinition of struct or union %qT with variably "
+ "modified type", t);
+ if (struct_parse_info->refloc != UNKNOWN_LOCATION)
+ inform (struct_parse_info->refloc, "originally defined here");
+ }
else if (!comptypes_same_p (t, vistype))
- error ("redefinition of struct or union %qT", t);
+ {
+ error ("redefinition of struct or union %qT", t);
+ if (struct_parse_info->refloc != UNKNOWN_LOCATION)
+ inform (struct_parse_info->refloc, "originally defined here");
+ }
}
}
diff --git a/gcc/testsuite/gcc.dg/gnu17-tag-1.c
b/gcc/testsuite/gcc.dg/gnu17-tag-1.c
new file mode 100644
index 00000000000..2c548aa50f4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gnu17-tag-1.c
@@ -0,0 +1,13 @@
+/* Test "originally defined" message for struct redefinition for C17. */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu17" } */
+
+struct s { int i; }; /* { dg-message "originally defined" } */
+struct s { int j; }; /* { dg-error "redefinition" } */
+
+void
+f (int x)
+{
+ struct t { int (*a)[x]; }; /* { dg-message "originally defined" } */
+ struct t { int (*a)[x]; }; /* { dg-error "redefinition" } */
+}
diff --git a/gcc/testsuite/gcc.dg/gnu23-tag-5.c
b/gcc/testsuite/gcc.dg/gnu23-tag-5.c
new file mode 100644
index 00000000000..bb5670e20bb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gnu23-tag-5.c
@@ -0,0 +1,13 @@
+/* Test "originally defined" message for struct redefinition for C23. */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu23" } */
+
+struct s { int i; }; /* { dg-message "originally defined" } */
+struct s { int j; }; /* { dg-error "redefinition" } */
+
+void
+f (int x)
+{
+ struct t { int (*a)[x]; }; /* { dg-message "originally defined" } */
+ struct t { int (*a)[x]; }; /* { dg-error "redefinition" } */
+}
--
Joseph S. Myers
josmy...@redhat.com
