Bootstrapped and regtested on x86_64-pc-linux-gnu. This isn't really a
bugfix but I think it's a simple improvement, OK for trunk?
Or otherwise for GCC 17?
-- >8 --
This adds another case to static_assert to print a helpful diagnostic
when comparing reflections. This makes it easier to see what's gone
wrong when doing 'static_assert(some_query(^^a) == some_query(^^b));'
by decomposing the resulting resulting reflection.
There's no need to do this decomposition in cases where both operands
are already in their lowest form however, e.g. for cases like
static_assert(^^int == ^^double).
gcc/cp/ChangeLog:
* constexpr.cc (diagnose_failing_condition): Also decompose
comparisons of reflections.
gcc/testsuite/ChangeLog:
* g++.dg/reflect/diag5.C: New test.
Signed-off-by: Nathaniel Shead <[email protected]>
---
gcc/cp/constexpr.cc | 10 +++++++---
gcc/testsuite/g++.dg/reflect/diag5.C | 9 +++++++++
2 files changed, 16 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/reflect/diag5.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 44e6b352d9a..4169f571285 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -3107,12 +3107,16 @@ diagnose_failing_condition (tree bad, location_t cloc,
bool show_expr_p,
else if (maybe_diagnose_standard_trait (cloc, bad))
;
else if (COMPARISON_CLASS_P (bad)
- && ARITHMETIC_TYPE_P (TREE_TYPE (TREE_OPERAND (bad, 0))))
+ && (ARITHMETIC_TYPE_P (TREE_TYPE (TREE_OPERAND (bad, 0)))
+ || REFLECTION_TYPE_P (TREE_TYPE (TREE_OPERAND (bad, 0)))))
{
tree op0 = fold_operand (TREE_OPERAND (bad, 0), ctx);
tree op1 = fold_operand (TREE_OPERAND (bad, 1), ctx);
- tree cond = build2 (TREE_CODE (bad), boolean_type_node, op0, op1);
- inform (cloc, "the comparison reduces to %qE", cond);
+ if (op0 != TREE_OPERAND (bad, 0) || op1 != TREE_OPERAND (bad, 1))
+ {
+ tree cond = build2 (TREE_CODE (bad), boolean_type_node, op0, op1);
+ inform (cloc, "the comparison reduces to %qE", cond);
+ }
}
else if (show_expr_p)
inform (cloc, "%qE evaluates to false", bad);
diff --git a/gcc/testsuite/g++.dg/reflect/diag5.C
b/gcc/testsuite/g++.dg/reflect/diag5.C
new file mode 100644
index 00000000000..44af952415d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/reflect/diag5.C
@@ -0,0 +1,9 @@
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+// Test that we decompose reflections in static_asserts, where applicable.
+
+constexpr auto a = ^^int;
+consteval auto b() { return ^^double; }
+
+static_assert(a == b()); // { dg-error "static assertion failed" }
+// { dg-message "the comparison reduces to '(^^int == ^^double)'" "" { target
*-*-* } .-1 }
--
2.51.0
