This was finally fixed for GCC 11 by r11-434.
Tested x86_64-pc-linux-gnu, applying to trunk.
PR c++/78244
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/Wnarrowing20.C: New test.
---
gcc/testsuite/g++.dg/cpp0x/Wnarrowing20.C | 26 +++++++++++++++++++++++
1 file changed, 26 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/Wnarrowing20.C
diff --git a/gcc/testsuite/g++.dg/cpp0x/Wnarrowing20.C
b/gcc/testsuite/g++.dg/cpp0x/Wnarrowing20.C
new file mode 100644
index 00000000000..17a6001266d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/Wnarrowing20.C
@@ -0,0 +1,26 @@
+// PR c++/78244
+// { dg-do compile { target c++11 } }
+
+struct S { S(int); int d; };
+
+template <typename T>
+auto f1() -> decltype(S{2.0}, void()) { } // { dg-error "narrowing conversion"
}
+
+template <typename T>
+auto f2() -> decltype(S{2.0}, 1) { return 1; } // { dg-error "narrowing
conversion" }
+
+template <typename T>
+auto f3() -> decltype(void(), S{2.0}, 1) { return 1; } // { dg-error
"narrowing conversion" }
+
+template <typename T>
+auto f4() -> decltype((S{2.0}, 1)) { return 1; } // { dg-error "narrowing
conversion" }
+
+// Test OVERLOAD in a template.
+int id(int v) { return v; }
+double id(double v) { return v; }
+
+template <typename T>
+auto f5(double v) -> decltype((S{id(v)}, 1)) { return 1; } // { dg-error
"narrowing conversion" }
+
+template <typename T>
+auto f6(int v) -> decltype((S{id(v)}, 1)) { return 1; }
base-commit: e1115a4f1b4afb346341237355186949f8e568a8
--
2.35.1
