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C++ PATCH for c++/88216, ICE with class type in non-type template parameter
- From: Marek Polacek <polacek at redhat dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>, Jason Merrill <jason at redhat dot com>
- Date: Mon, 10 Dec 2018 14:52:15 -0500
- Subject: C++ PATCH for c++/88216, ICE with class type in non-type template parameter
Here we were crashing in cxx_eval_constant_expression:
4600 /* We can only get here in checking mode via
4601 build_non_dependent_expr, because any expression that
4602 calls or takes the address of the function will have
4603 pulled a FUNCTION_DECL out of the COMPONENT_REF. */
4604 gcc_checking_assert (ctx->quiet || errorcount);
4605 *non_constant_p = true;
4606 return t;
4607 }
where we got via
6661 if (!TREE_CONSTANT (expr))
6662 {
6663 if ((complain & tf_error)
6664 && require_rvalue_constant_expression (expr))
6665 cxx_constant_value (expr);
6666 return error_mark_node;
6667 }
because the expr wasn't constant. The fix would be to add error() I think.
But the testcase is valid, so we need (also) something else. This problem
occurs when using a class type non-type template parameter as a template
argument, because the TREE_CONSTANT check in get_template_parm_object will
fail--we're in a template and build_converted_constant_expr didn't produce
a constant, because the expression contains template codes. So I thought
it would make sense to just return and create the template parameter object
at instantiation.
But then I was running into sorry() in the demangler so I had to make tweaks
there too. I don't know much about that code, so I hope I'm not doing anything
overly stoopid.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2018-12-10 Marek Polacek <polacek@redhat.com>
PR c++/88216 - ICE with class type in non-type template parameter.
* mangle.c (write_expression): Handle TARGET_EXPR and
VIEW_CONVERT_EXPR.
* pt.c (get_template_parm_object): Just return for value dependent
expressions.
* g++.dg/cpp2a/nontype-class9.C: New test.
diff --git gcc/cp/mangle.c gcc/cp/mangle.c
index 64415894bc5..56247883010 100644
--- gcc/cp/mangle.c
+++ gcc/cp/mangle.c
@@ -2836,13 +2836,21 @@ write_expression (tree expr)
{
enum tree_code code = TREE_CODE (expr);
+ if (TREE_CODE (expr) == TARGET_EXPR)
+ {
+ expr = TARGET_EXPR_INITIAL (expr);
+ code = TREE_CODE (expr);
+ }
+
/* Skip NOP_EXPR and CONVERT_EXPR. They can occur when (say) a pointer
argument is converted (via qualification conversions) to another type. */
while (CONVERT_EXPR_CODE_P (code)
|| location_wrapper_p (expr)
/* Parentheses aren't mangled. */
|| code == PAREN_EXPR
- || code == NON_LVALUE_EXPR)
+ || code == NON_LVALUE_EXPR
+ || (code == VIEW_CONVERT_EXPR
+ && TREE_CODE (TREE_OPERAND (expr, 0)) == TEMPLATE_PARM_INDEX))
{
expr = TREE_OPERAND (expr, 0);
code = TREE_CODE (expr);
diff --git gcc/cp/pt.c gcc/cp/pt.c
index 8560e588593..878a354b193 100644
--- gcc/cp/pt.c
+++ gcc/cp/pt.c
@@ -6655,6 +6655,9 @@ invalid_tparm_referent_p (tree type, tree expr, tsubst_flags_t complain)
static tree
get_template_parm_object (tree expr, tsubst_flags_t complain)
{
+ if (processing_template_decl && value_dependent_expression_p (expr))
+ return expr;
+
if (TREE_CODE (expr) == TARGET_EXPR)
expr = TARGET_EXPR_INITIAL (expr);
diff --git gcc/testsuite/g++.dg/cpp2a/nontype-class9.C gcc/testsuite/g++.dg/cpp2a/nontype-class9.C
new file mode 100644
index 00000000000..737f712be47
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp2a/nontype-class9.C
@@ -0,0 +1,29 @@
+// PR c++/88216
+// { dg-do compile { target c++2a } }
+
+template <class T, class U> struct same;
+template <class T> struct same<T,T> {};
+
+struct T { };
+
+template <T t>
+struct U { };
+
+template <T t>
+void f (U<t>)
+{
+ same<T,decltype(t)> s;
+ same<const T&,decltype((t))> s2;
+}
+
+template<T t>
+U<t> u;
+
+T t;
+U<t> u2;
+
+void
+g ()
+{
+ f<t>(u2);
+}