This patch improves our concept diagnostics in two ways. First, it sets a more
precise location for the constraint expressions built in
finish_constraint_binary_op. As a result, when a disjunction is unsatisfied we
now print e.g.
.../include/bits/range_access.h:467:2: note: neither operand of the disjunction
is satisfied
466 | requires is_bounded_array_v<remove_reference_t<_Tp>> ||
__member_end<_Tp>
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
467 | || __adl_end<_Tp>
| ^~~~~~~~~~~~~~~~~
instead of
.../include/bits/range_access.h:467:2: note: neither operand of the disjunction
is satisfied
467 | || __adl_end<_Tp>
| ^~
Second, this patch changes diagnose_atomic_constraint to pretty-print
unsatisfied atomic constraint expressions with their template arguments
substituted in (if doing so does not result in a trivial expression). So for
example we now emit
cpp2a/concepts-pr67719.C:9:8: note: the expression ‘((C<int>() && C<long
int>()) && C<void>())’ evaluated to ‘false’
instead of
cpp2a/concepts-pr67719.C:9:8: note: the expression ‘(... &&(C<Tx>)())’
evaluated to ‘false’
Tested on x86_64-pc-linux-gnu, and verified that all the diagnostics emitted in
our concept tests are no worse with this patch. Does this look OK to commit?
gcc/cp/ChangeLog:
* constraint.cc (finish_constraint_binary_op): Set expr's location range
to the range of its operands.
(diagnose_atomic_constraint): Prefer to pretty-print the atomic
constraint with template arguments substituted in.
gcc/testsuite/ChangeLog:
* g++.dg/concepts/diagnostic2.C: New test.
* g++.dg/concepts/diagnostic3.C: New test.
---
gcc/cp/constraint.cc | 15 +++++++----
gcc/testsuite/g++.dg/concepts/diagnostic2.C | 30 +++++++++++++++++++++
gcc/testsuite/g++.dg/concepts/diagnostic3.C | 19 +++++++++++++
3 files changed, 59 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/concepts/diagnostic2.C
create mode 100644 gcc/testsuite/g++.dg/concepts/diagnostic3.C
diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index 58044cd0f9d..4f6bc11e7e8 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -155,14 +155,14 @@ finish_constraint_binary_op (location_t loc,
if (!check_constraint_operands (loc, lhs, rhs))
return error_mark_node;
tree overload;
- tree expr = build_x_binary_op (loc, code,
- lhs, TREE_CODE (lhs),
- rhs, TREE_CODE (rhs),
- &overload, tf_none);
+ cp_expr expr = build_x_binary_op (loc, code,
+ lhs, TREE_CODE (lhs),
+ rhs, TREE_CODE (rhs),
+ &overload, tf_none);
/* When either operand is dependent, the overload set may be non-empty. */
if (expr == error_mark_node)
return error_mark_node;
- SET_EXPR_LOCATION (expr, loc);
+ expr.set_range (lhs.get_start (), rhs.get_finish ());
return expr;
}
@@ -3330,6 +3330,11 @@ diagnose_atomic_constraint (tree t, tree args,
subst_info info)
inform (loc, "%qE is never satisfied", expr);
break;
default:
+ tree orig_expr = expr;
+ expr = tsubst_expr (expr, args, tf_none, NULL_TREE, false);
+ if (CONSTANT_CLASS_P (expr))
+ /* We are better off printing the original expression. */
+ expr = orig_expr;
inform (loc, "the expression %qE evaluated to %<false%>", expr);
}
}
diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic2.C
b/gcc/testsuite/g++.dg/concepts/diagnostic2.C
new file mode 100644
index 00000000000..ce51b71fa8b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/diagnostic2.C
@@ -0,0 +1,30 @@
+// { dg-do compile { target c++2a } }
+// { dg-options "-fdiagnostics-show-caret" }
+
+template<typename T>
+ inline constexpr bool foo_v = false;
+
+template<typename T>
+ concept foo = foo_v<T> || foo_v<T&>; // { dg-message "neither operand" }
+/* { dg-begin-multiline-output "" }
+ concept foo = foo_v<T> || foo_v<T&>;
+ ~~~~~~~~~^~~~~~~~~~~~
+ { dg-end-multiline-output "" } */
+
+template<typename T>
+ requires foo<T>
+ void bar();
+/* { dg-begin-multiline-output "" }
+ void bar();
+ { dg-end-multiline-output "" } */
+/* { dg-prune-output "~" } */
+
+void
+baz()
+{
+ bar<int>(); // { dg-error "unsatisfied constraints" }
+/* { dg-begin-multiline-output "" }
+ bar<int>();
+ ^
+ { dg-end-multiline-output "" } */
+}
diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic3.C
b/gcc/testsuite/g++.dg/concepts/diagnostic3.C
new file mode 100644
index 00000000000..e0649dac51a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/diagnostic3.C
@@ -0,0 +1,19 @@
+// { dg-do compile { target c++2a } }
+
+template<typename T>
+ inline constexpr bool foo_v = false;
+
+template<typename T>
+ concept foo = (bool)(foo_v<T> | foo_v<T&>); // { dg-message
"foo_v<int>.*foo_v<int&>" }
+
+template<typename T>
+requires foo<T>
+void
+bar()
+{ }
+
+void
+baz()
+{
+ bar<int>(); // { dg-error "unsatisfied constraints" }
+}
--
2.25.1.291.ge68e29171c
