Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
During speculative constant folding of an if consteval, we take the false
branch, but the true branch is an immediate function context, so we don't
want to to cp_fold_immediate it. So we could check IF_STMT_CONSTEVAL_P
here. But beyond that, we don't want to do this inside a call, only when
first parsing a function.
PR c++/115583
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_conditional_expression): Don't
cp_fold_immediate for if consteval.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/consteval-if13.C: New test.
---
gcc/cp/constexpr.cc | 7 +++++--
gcc/testsuite/g++.dg/cpp23/consteval-if13.C | 17 +++++++++++++++++
2 files changed, 22 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp23/consteval-if13.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index abd3b04ea7f..8277b3b79ba 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -3974,10 +3974,13 @@ cxx_eval_conditional_expression (const constexpr_ctx
*ctx, tree t,
if (TREE_CODE (t) == IF_STMT && !val)
val = void_node;
- /* P2564: a subexpression of a manifestly constant-evaluated expression
- or conversion is an immediate function context. */
+ /* P2564: If we aren't in immediate function context (including a manifestly
+ constant-evaluated expression), check any uses of immediate functions in
+ the arm we're discarding. But don't do this inside a call; we already
+ checked when parsing the function. */
if (ctx->manifestly_const_eval != mce_true
&& !in_immediate_context ()
+ && !ctx->call
&& cp_fold_immediate (&TREE_OPERAND (t, zero_p ? 1 : 2),
ctx->manifestly_const_eval))
{
diff --git a/gcc/testsuite/g++.dg/cpp23/consteval-if13.C
b/gcc/testsuite/g++.dg/cpp23/consteval-if13.C
new file mode 100644
index 00000000000..b98bbc33d13
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/consteval-if13.C
@@ -0,0 +1,17 @@
+// PR c++/115583
+// { dg-do compile { target c++23 } }
+
+consteval int f(int i) {
+ return i;
+}
+const bool b = 0;
+constexpr int g(int i) {
+ if consteval {
+ return f(i);
+ } else {
+ return i;
+ }
+}
+int main() {
+ return g(1);
+}
base-commit: 027bde11d44d58e6ad473af3a69dc21b451bcbc0
--
2.45.2
