[PATCH] c++: improve location of fold expressions

[Patrick Palka via Gcc-patches]

This improves diagnostic quality for unsatisfied atomic constraints
that consist of a fold expression, e.g. in concepts/diagnostics3.C:

  .../diagnostic3.C:10:22: note: the expression ‘(foo<Ts> && ...) [with Ts = 
{int, char}]’ evaluated to ‘false’
     10 | requires (foo<Ts> && ...)
        |          ~~~~~~~~~~~~^~~~

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?

gcc/cp/ChangeLog:

        * semantics.cc (finish_unary_fold_expr): Use input_location
        instead of UNKNOWN_LOCATION.
        (finish_binary_fold_expr): Likewise.

gcc/testsuite/ChangeLog:

        * g++.dg/concepts/diagnostic3.C: Adjusted expected location of
        "evaluated to false" diagnostics.
---
 gcc/cp/semantics.cc                         | 4 ++--
 gcc/testsuite/g++.dg/concepts/diagnostic3.C | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index a2c0eb050e6..07cae993efe 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12185,7 +12185,7 @@ finish_unary_fold_expr (tree expr, int op, tree_code 
dir)
 
   /* Build the fold expression.  */
   tree code = build_int_cstu (integer_type_node, abs (op));
-  tree fold = build_min_nt_loc (UNKNOWN_LOCATION, dir, code, pack);
+  tree fold = build_min_nt_loc (input_location, dir, code, pack);
   FOLD_EXPR_MODIFY_P (fold) = (op < 0);
   TREE_TYPE (fold) = build_dependent_operator_type (NULL_TREE,
                                                    FOLD_EXPR_OP (fold),
@@ -12214,7 +12214,7 @@ finish_binary_fold_expr (tree pack, tree init, int op, 
tree_code dir)
 {
   pack = make_pack_expansion (pack);
   tree code = build_int_cstu (integer_type_node, abs (op));
-  tree fold = build_min_nt_loc (UNKNOWN_LOCATION, dir, code, pack, init);
+  tree fold = build_min_nt_loc (input_location, dir, code, pack, init);
   FOLD_EXPR_MODIFY_P (fold) = (op < 0);
   TREE_TYPE (fold) = build_dependent_operator_type (NULL_TREE,
                                                    FOLD_EXPR_OP (fold),
diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic3.C 
b/gcc/testsuite/g++.dg/concepts/diagnostic3.C
index 7796e264251..410651a9c1a 100644
--- a/gcc/testsuite/g++.dg/concepts/diagnostic3.C
+++ b/gcc/testsuite/g++.dg/concepts/diagnostic3.C
@@ -7,18 +7,18 @@ template<typename T>
   concept foo = (bool)(foo_v<T> | foo_v<T&>);
 
 template<typename... Ts>
-requires (foo<Ts> && ...)
+requires (foo<Ts> && ...) // { dg-message "with Ts = .int, char... evaluated 
to .false." }
 void
-bar() // { dg-message "with Ts = .int, char... evaluated to .false." }
+bar()
 { }
 
 template<int>
 struct S { };
 
 template<int... Is>
-requires (foo<S<Is>> && ...)
+requires (foo<S<Is>> && ...) // { dg-message "with Is = .2, 3, 4... evaluated 
to .false." }
 void
-baz() // { dg-message "with Is = .2, 3, 4... evaluated to .false." }
+baz()
 { }
 
 void
-- 
2.35.1.354.g715d08a9e5