Hello,
Consider this short code snippet:
struct A
{
virtual void foo();
};
template <typename T>
void
bar(T x)
{
A &b = *x;
b.foo();
}
When we look at b.foo() during the parsing (in
cp_parser_postfix_expression), 'b.foo()' is (rightfully) considered
non-dependent. So we go on an build the method call expression. Then
build_new_method_call wants to know the determine the dynamic type of
'b' and uses fixed_type_or_null for that.
fixed_type_or_null goes to look into the initializer of the reference
variable 'b', which is dependent; and it crashes while trying to poke at
the type of the INDIRECT_REF '*x', which has no type yet (because it's
dependent).
The patch below makes fixed_type_or_null consider that it cannot
determine the dynamic type of a reference variable if its initializer is
dependent.
Tested on x86_64-unknown-linux-gnu against trunk.
gcc/cp/
* class.c (fixed_type_or_null): We cannot determine the dynamic
type of a reference variable if its initializer is dependent.
gcc/testsuite/
* g++.dg/template/dependent-expr7.C: New test case.
---
gcc/cp/class.c | 8 ++++++++
gcc/testsuite/g++.dg/template/dependent-expr7.C | 22 ++++++++++++++++++++++
2 files changed, 30 insertions(+), 0 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/template/dependent-expr7.C
diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index b6aebae..d40c11c 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -5944,6 +5944,14 @@ fixed_type_or_null (tree instance, int *nonnull, int
*cdtorp)
tree type;
void **slot;
+ if (type_dependent_expression_p (DECL_INITIAL (instance)))
+ {
+ /* The initializer is type dependent so we cannot
+ determine the dynamic type of this reference. */
+ if (nonnull)
+ *nonnull = 0;
+ return NULL_TREE;
+ }
slot = htab_find_slot (ht, instance, INSERT);
*slot = instance;
type = RECUR (DECL_INITIAL (instance));
diff --git a/gcc/testsuite/g++.dg/template/dependent-expr7.C
b/gcc/testsuite/g++.dg/template/dependent-expr7.C
new file mode 100644
index 0000000..b246820
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/dependent-expr7.C
@@ -0,0 +1,22 @@
+// Origin PR c++/48574
+// { dg-do compile }
+
+struct A
+{
+ virtual void foo();
+};
+
+template <typename T>
+void
+bar(T x)
+{
+ A &b = *x;
+ b.foo ();
+}
+
+void
+foo()
+{
+ A a;
+ bar(&a);
+}
--
Dodji
