From dcb4bd0789d13dd4d07428bff712d01d3ea71ebe Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Thu, 31 Mar 2022 16:18:58 -0400
Subject: [PATCH] c++: also note name used in enclosing class
While looking at PR96645 I noticed that while we were diagnosing names
changing meaning in the full class context, we weren't doing this for
lookups in nested class bodies.
Note that this breaks current range-v3; I've submitted a pull request to fix
its violation of the rule.
gcc/cp/ChangeLog:
* class.cc (maybe_note_name_used_in_class): Note in all enclosing
classes. Remember location of use.
(note_name_declared_in_class): Adjust.
gcc/testsuite/ChangeLog:
* g++.dg/lookup/name-clash13.C: New test.
* g++.dg/lookup/name-clash14.C: New test.
* g++.dg/lookup/name-clash15.C: New test.
* g++.dg/lookup/name-clash16.C: New test.
---
gcc/cp/class.cc | 61 +++++++++++++++-------
gcc/testsuite/g++.dg/lookup/name-clash13.C | 7 +++
gcc/testsuite/g++.dg/lookup/name-clash14.C | 9 ++++
gcc/testsuite/g++.dg/lookup/name-clash15.C | 14 +++++
gcc/testsuite/g++.dg/lookup/name-clash16.C | 13 +++++
5 files changed, 86 insertions(+), 18 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/lookup/name-clash13.C
create mode 100644 gcc/testsuite/g++.dg/lookup/name-clash14.C
create mode 100644 gcc/testsuite/g++.dg/lookup/name-clash15.C
create mode 100644 gcc/testsuite/g++.dg/lookup/name-clash16.C
diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc
index bfda0065bf46..bc94ed45e17e 100644
--- a/gcc/cp/class.cc
+++ b/gcc/cp/class.cc
@@ -8931,32 +8931,53 @@ is_really_empty_class (tree type, bool ignore_vptr)
void
maybe_note_name_used_in_class (tree name, tree decl)
{
- splay_tree names_used;
-
/* If we're not defining a class, there's nothing to do. */
if (!(innermost_scope_kind() == sk_class
&& TYPE_BEING_DEFINED (current_class_type)
&& !LAMBDA_TYPE_P (current_class_type)))
return;
- /* If there's already a binding for this NAME, then we don't have
- anything to worry about. */
- if (lookup_member (current_class_type, name,
- /*protect=*/0, /*want_type=*/false, tf_warning_or_error))
- return;
+ const cp_binding_level *blev = nullptr;
+ if (const cxx_binding *binding = IDENTIFIER_BINDING (name))
+ blev = binding->scope;
+ const cp_binding_level *lev = current_binding_level;
- if (!current_class_stack[current_class_depth - 1].names_used)
- current_class_stack[current_class_depth - 1].names_used
- = splay_tree_new (splay_tree_compare_pointers, 0, 0);
- names_used = current_class_stack[current_class_depth - 1].names_used;
+ /* Record the binding in the names_used tables for classes inside blev. */
+ for (int i = current_class_depth; i > 0; --i)
+ {
+ tree type = (i == current_class_depth
+ ? current_class_type
+ : current_class_stack[i].type);
- splay_tree_insert (names_used,
- (splay_tree_key) name,
- (splay_tree_value) decl);
+ for (; lev; lev = lev->level_chain)
+ {
+ if (lev == blev)
+ /* We found the declaration. */
+ return;
+ if (lev->kind == sk_class && lev->this_entity == type)
+ /* This class is inside the declaration scope. */
+ break;
+ }
+
+ auto &names_used = current_class_stack[i-1].names_used;
+ if (!names_used)
+ names_used = splay_tree_new (splay_tree_compare_pointers, 0, 0);
+
+ tree use = build1_loc (input_location, VIEW_CONVERT_EXPR,
+ TREE_TYPE (decl), decl);
+ EXPR_LOCATION_WRAPPER_P (use) = 1;
+ splay_tree_insert (names_used,
+ (splay_tree_key) name,
+ (splay_tree_value) use);
+ }
}
/* Note that NAME was declared (as DECL) in the current class. Check
- to see that the declaration is valid. */
+ to see that the declaration is valid under [class.member.lookup]:
+
+ If [the result of a search in T for N at point P] differs from the result of
+ a search in T for N from immediately after the class-specifier of T, the
+ program is ill-formed, no diagnostic required. */
void
note_name_declared_in_class (tree name, tree decl)
@@ -8979,6 +9000,9 @@ note_name_declared_in_class (tree name, tree decl)
n = splay_tree_lookup (names_used, (splay_tree_key) name);
if (n)
{
+ tree use = (tree) n->value;
+ location_t loc = EXPR_LOCATION (use);
+ tree olddecl = OVL_FIRST (TREE_OPERAND (use, 0));
/* [basic.scope.class]
A name N used in a class S shall refer to the same declaration
@@ -8987,9 +9011,10 @@ note_name_declared_in_class (tree name, tree decl)
if (permerror (location_of (decl),
"declaration of %q#D changes meaning of %qD",
decl, OVL_NAME (decl)))
- inform (location_of ((tree) n->value),
- "%qD declared here as %q#D",
- OVL_NAME (decl), (tree) n->value);
+ {
+ inform (loc, "used here to mean %q#D", olddecl);
+ inform (location_of (olddecl), "declared here" );
+ }
}
}
diff --git a/gcc/testsuite/g++.dg/lookup/name-clash13.C b/gcc/testsuite/g++.dg/lookup/name-clash13.C
new file mode 100644
index 000000000000..ce43435f0114
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/name-clash13.C
@@ -0,0 +1,7 @@
+typedef int T;
+struct A {
+ struct B {
+ static T t;
+ };
+ typedef float T; // { dg-error "changes meaning" }
+};
diff --git a/gcc/testsuite/g++.dg/lookup/name-clash14.C b/gcc/testsuite/g++.dg/lookup/name-clash14.C
new file mode 100644
index 000000000000..71305ba082c7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/name-clash14.C
@@ -0,0 +1,9 @@
+const int x = 24;
+struct A
+{
+ struct B
+ {
+ enum { E = x };
+ };
+ static const int x = 42; // { dg-error "changes meaning" }
+};
diff --git a/gcc/testsuite/g++.dg/lookup/name-clash15.C b/gcc/testsuite/g++.dg/lookup/name-clash15.C
new file mode 100644
index 000000000000..5c123bf7005e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/name-clash15.C
@@ -0,0 +1,14 @@
+struct C {
+ static const int x = 24;
+};
+
+struct A
+{
+ struct B: C
+ {
+ enum { E = x };
+ };
+
+ // OK, earlier x was found in a base, lookup didn't pass through A.
+ static const int x = 42;
+};
diff --git a/gcc/testsuite/g++.dg/lookup/name-clash16.C b/gcc/testsuite/g++.dg/lookup/name-clash16.C
new file mode 100644
index 000000000000..250d6147c73c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/name-clash16.C
@@ -0,0 +1,13 @@
+typedef int T;
+
+struct A
+{
+ template <class T>
+ struct B
+ {
+ T t;
+ };
+
+ // OK, earlier T was found in template header, didn't look in A.
+ typedef float T;
+};
--
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