On 4/28/20 9:48 AM, Patrick Palka wrote:
When printing the substituted parameter list of a requires-expression as
part of the "in requirements with ..." context line during concepts
diagnostics, we weren't considering that substitution into a parameter
pack can yield zero or multiple parameters.
Since this patch affects only concepts diagnostics, so far I tested with
RUNTESTFLAGS="dg.exp=*concepts*" and also verified that we no longer ICE
with the unreduced testcase in the PR. Is this OK to commit after a
full bootstrap and regtest?
OK.
Though I wonder about printing the dependent form and template arguments
instead. Do you have an opinion?
gcc/cp/ChangeLog:
PR c++/94808
* error.c (print_requires_expression_info): Substitute into and
collect all parameters in a vector first before printing them.
Handle zero or multiple parameters of an expanded parameter
pack.
gcc/testsuite/ChangeLog:
PR c++/94808
* g++.dg/concepts/diagnostic12.C: New test.
---
gcc/cp/error.c | 21 ++++++++++++++------
gcc/testsuite/g++.dg/concepts/diagnostic12.C | 14 +++++++++++++
2 files changed, 29 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/concepts/diagnostic12.C
diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index 98c163db572..a314412988f 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -3752,8 +3752,7 @@ print_requires_expression_info (diagnostic_context
*context, tree constr, tree a
pp_verbatim (context->printer, "in requirements ");
tree parms = TREE_OPERAND (expr, 0);
- if (parms)
- pp_verbatim (context->printer, "with ");
+ auto_vec<tree> substed_parms;
while (parms)
{
tree next = TREE_CHAIN (parms);
@@ -3761,15 +3760,25 @@ print_requires_expression_info (diagnostic_context
*context, tree constr, tree a
TREE_CHAIN (parms) = NULL_TREE;
cp_unevaluated u;
tree p = tsubst (parms, args, tf_none, NULL_TREE);
- pp_verbatim (context->printer, "%q#D", p);
+ while (p)
+ {
+ substed_parms.safe_push (p);
+ p = TREE_CHAIN (p);
+ }
TREE_CHAIN (parms) = next;
- if (next)
- pp_separate_with_comma ((cxx_pretty_printer *)context->printer);
-
parms = next;
}
+ for (unsigned i = 0; i < substed_parms.length (); i++)
+ {
+ if (i == 0)
+ pp_verbatim (context->printer, "with ");
+ else
+ pp_separate_with_comma ((cxx_pretty_printer *)context->printer);
+ pp_verbatim (context->printer, "%q#D", substed_parms[i]);
+ }
+
pp_verbatim (context->printer, "\n");
}
diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic12.C b/gcc/testsuite/g++.dg/concepts/diagnostic12.C
new file mode 100644
index 00000000000..7dd286291f3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/diagnostic12.C
@@ -0,0 +1,14 @@
+// PR c++/94808
+// { dg-do compile { target concepts } }
+
+template<typename T, typename... Args>
+ concept c1 = requires (T t, Args... args) { *t; };
+// { dg-message "in requirements with .int t." "" { target *-*-* } .-1 }
+
+static_assert(c1<int>); // { dg-error "failed" }
+
+template<typename T, typename... Args>
+ concept c2 = requires (T t, Args... args) { *t; };
+// { dg-message "in requirements with .int t., .char args#0., .bool args#1."
"" { target *-*-* } .-1 }
+
+static_assert(c2<int, char, bool>); // { dg-error "failed" }
