On Thu, Sep 05, 2024 at 10:42:22AM -0400, Jason Merrill wrote:
> On 9/4/24 1:18 PM, Marek Polacek wrote:
> > On Wed, Sep 04, 2024 at 12:28:49PM -0400, Jason Merrill wrote:
>
> > > > + if (!validate_constexpr_redeclaration (alias, decl))
> > > > + return;
> > > > +
> > > > retrofit_lang_decl (decl);
> > > > DECL_LOCAL_DECL_ALIAS (decl) = alias;
> > > > }
> > >
> > > I don't think we need this in the case that we built a new alias and
> > > pushed
> > > it; in that case alias is built from decl, and should certainly match
> > > already. So let's put this call before we decide to build a new alias,
> > > either in the loop or just after it.
> >
> > That's right. How about this?
>
> Hmm, I'd still prefer to have it *before* the !alias case for locality;
> putting it as an else to a 66-line if seems obscure.
>
> But OK however.
Ah, let me change it. Still OK? dg.exp passed.
-- >8 --
Redeclaration such as
void f(void);
consteval void f(void);
is invalid. In a namespace scope, we detect the collision in
validate_constexpr_redeclaration, but not when one declaration is
at block scope.
When we have
void f(void);
void g() { consteval void f(void); }
we call pushdecl on the second f and call push_local_extern_decl_alias.
It finds the namespace-scope f:
for (ovl_iterator iter (binding); iter; ++iter)
if (decls_match (decl, *iter, /*record_versions*/false))
{
alias = *iter;
break;
}
but decls_match says they match so we just set DECL_LOCAL_DECL_ALIAS
(and do not call another pushdecl leading to duplicate_decls which
would detect mismatching return types, for example). I don't think
we want to change decls_match, so a simple fix is to detect the
problem in push_local_extern_decl_alias.
PR c++/116239
gcc/cp/ChangeLog:
* cp-tree.h (validate_constexpr_redeclaration): Declare.
* decl.cc (validate_constexpr_redeclaration): No longer static.
* name-lookup.cc (push_local_extern_decl_alias): Call
validate_constexpr_redeclaration.
gcc/testsuite/ChangeLog:
* g++.dg/diagnostic/redeclaration-6.C: New test.
---
gcc/cp/cp-tree.h | 1 +
gcc/cp/decl.cc | 2 +-
gcc/cp/name-lookup.cc | 2 ++
.../g++.dg/diagnostic/redeclaration-6.C | 34 +++++++++++++++++++
4 files changed, 38 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 2eeb5e3e8b1..1a763b683de 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6992,6 +6992,7 @@ extern bool member_like_constrained_friend_p (tree);
extern bool fns_correspond (tree, tree);
extern int decls_match (tree, tree, bool = true);
extern bool maybe_version_functions (tree, tree, bool);
+extern bool validate_constexpr_redeclaration (tree, tree);
extern bool merge_default_template_args (tree, tree, bool);
extern tree duplicate_decls (tree, tree,
bool hiding = false,
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 7bad3047ad9..f4128dbccdf 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -1412,7 +1412,7 @@ check_redeclaration_exception_specification (tree
new_decl,
/* Return true if OLD_DECL and NEW_DECL agree on constexprness.
Otherwise issue diagnostics. */
-static bool
+bool
validate_constexpr_redeclaration (tree old_decl, tree new_decl)
{
old_decl = STRIP_TEMPLATE (old_decl);
diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index 7a6cc244c15..cd3947cbe4f 100644
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -3637,6 +3637,8 @@ push_local_extern_decl_alias (tree decl)
if (decls_match (decl, *iter, /*record_versions*/false))
{
alias = *iter;
+ if (!validate_constexpr_redeclaration (alias, decl))
+ return;
break;
}
diff --git a/gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C
b/gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C
new file mode 100644
index 00000000000..ed8d4af7792
--- /dev/null
+++ b/gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C
@@ -0,0 +1,34 @@
+// PR c++/116239
+// { dg-do compile { target c++20 } }
+
+consteval void f1();
+void f2();
+constexpr void f3();
+void f4();
+consteval void f5();
+constexpr void f6();
+
+void
+g ()
+{
+ void f1(); // { dg-error "differs in .consteval." }
+ consteval void f2(); // { dg-error "differs in .consteval." }
+
+ void f3(); // { dg-error "differs in .constexpr." }
+ constexpr void f4(); // { dg-error "differs in .constexpr." }
+
+ consteval void f5();
+ constexpr void f6();
+
+ void f7();
+ consteval void f7(); // { dg-error "differs in .consteval." }
+
+ consteval void f8();
+ void f8(); // { dg-error "differs in .consteval." }
+
+ void f9();
+ constexpr void f9(); // { dg-error "differs in .constexpr." }
+
+ constexpr void f10();
+ void f10(); // { dg-error "differs in .constexpr." }
+}
base-commit: ae88e91938af364ef5613e5461b12b484b578bc5
--
2.46.0
