convert_like issues errors about bad_p conversions at the beginning
of the function, but in the ck_ref_bind case, it only issues them
after we've called convert_like on the next conversion.
This doesn't work as expected since r10-7096 because when we see
a conversion from/to class type in a template, we return early, thereby
missing the error, and a bad_p conversion goes by undetected. That
made the attached test to compile even though it should not.
I had thought that I could just move the ck_ref_bind/bad_p errors
above to the rest of them, but that regressed diagnostics because
expr then wasn't converted yet by the nested convert_like_real call.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk and 10?
gcc/cp/ChangeLog:
PR c++/95789
* call.c (convert_like_real): Do the normal processing for
ck_ref_bind conversion that are bad_p.
gcc/testsuite/ChangeLog:
PR c++/95789
* g++.dg/conversion/ref4.C: New test.
---
gcc/cp/call.c | 9 ++++++++-
gcc/testsuite/g++.dg/conversion/ref4.C | 22 ++++++++++++++++++++++
2 files changed, 30 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/conversion/ref4.C
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 2b39a3700fc..7b16895d5db 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -7402,7 +7402,14 @@ convert_like_real (conversion *convs, tree expr, tree
fn, int argnum,
function. */
if (processing_template_decl
&& convs->kind != ck_identity
- && (CLASS_TYPE_P (totype) || CLASS_TYPE_P (TREE_TYPE (expr))))
+ && (CLASS_TYPE_P (totype) || CLASS_TYPE_P (TREE_TYPE (expr)))
+ /* Do the normal processing to give the bad_p errors in ck_ref_bind
+ to avoid losing the fact that this conversion was bad. Since we
+ are going to return error_mark_node, we don't care about trees
+ breaking in templates. */
+ && !(convs->kind == ck_ref_bind
+ && convs->bad_p
+ && !next_conversion (convs)->bad_p))
{
expr = build1 (IMPLICIT_CONV_EXPR, totype, expr);
return convs->kind == ck_ref_bind ? expr : convert_from_reference (expr);
diff --git a/gcc/testsuite/g++.dg/conversion/ref4.C
b/gcc/testsuite/g++.dg/conversion/ref4.C
new file mode 100644
index 00000000000..464a4cf6c0f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/conversion/ref4.C
@@ -0,0 +1,22 @@
+// PR c++/95789
+// { dg-do compile { target c++11 } }
+
+struct B {
+ int n;
+};
+
+template <typename T>
+struct A {
+ B& get() const { return f; } // { dg-error "binding reference" }
+
+ B f;
+};
+
+int main() {
+ A<int> a;
+ a.f = {};
+
+ a.get().n = 10;
+ if (a.f.n != 0)
+ __builtin_abort();
+}
base-commit: 0164e59835de81d758fd4c56248ad7a46435fbfa
--
Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
