Jonathan pointed me at this issue where
constexpr unsigned f() { constexpr int n = -1; return unsigned{n}; }
is accepted in system headers, despite the narrowing conversion from
a constant. I suspect that whereas narrowing warnings should be
disabled, ill-formed narrowing of constants should be a hard error
(which can still be disabled by -Wno-narrowing).
Bootstrapped/regtested on {ppc64le,x86_64}-pc-linux-gnu, ok for trunk?
gcc/cp/ChangeLog:
* typeck2.c (check_narrowing): Don't suppress the pedantic error
in system headers.
libstdc++-v3/ChangeLog:
* testsuite/20_util/ratio/operations/ops_overflow_neg.cc: Add
dg-error.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/Wnarrowing2.C: New test.
* g++.dg/cpp1y/Wnarrowing2.h: New test.
---
gcc/cp/typeck2.c | 1 +
gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.C | 4 ++++
gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.h | 2 ++
.../testsuite/20_util/ratio/operations/ops_overflow_neg.cc | 2 ++
4 files changed, 9 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.h
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index 6679e247816..dcfdff2f905 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -986,6 +986,7 @@ check_narrowing (tree type, tree init, tsubst_flags_t
complain,
{
int savederrorcount = errorcount;
global_dc->pedantic_errors = 1;
+ auto s = make_temp_override (global_dc->dc_warn_system_headers, true);
pedwarn (loc, OPT_Wnarrowing,
"narrowing conversion of %qE from %qH to %qI",
init, ftype, type);
diff --git a/gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.C
b/gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.C
new file mode 100644
index 00000000000..048d484f46f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.C
@@ -0,0 +1,4 @@
+// { dg-do compile { target c++14 } }
+
+#include "Wnarrowing2.h"
+// { dg-error "narrowing conversion" "" { target *-*-* } 0 }
diff --git a/gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.h
b/gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.h
new file mode 100644
index 00000000000..7dafa51af14
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/Wnarrowing2.h
@@ -0,0 +1,2 @@
+#pragma GCC system_header
+constexpr unsigned f() { constexpr int n = -1; return unsigned{n}; }
diff --git
a/libstdc++-v3/testsuite/20_util/ratio/operations/ops_overflow_neg.cc
b/libstdc++-v3/testsuite/20_util/ratio/operations/ops_overflow_neg.cc
index 47d3c3a037e..f120e599a33 100644
--- a/libstdc++-v3/testsuite/20_util/ratio/operations/ops_overflow_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/ratio/operations/ops_overflow_neg.cc
@@ -39,6 +39,7 @@ test02()
}
// { dg-error "required from here" "" { target *-*-* } 28 }
+// { dg-error "expected initializer" "" { target *-*-* } 28 }
// { dg-error "expected initializer" "" { target *-*-* } 35 }
// { dg-error "expected initializer" "" { target *-*-* } 37 }
// { dg-error "overflow in addition" "" { target *-*-* } 0 }
@@ -46,5 +47,6 @@ test02()
// { dg-error "overflow in multiplication" "" { target *-*-* } 100 }
// { dg-error "overflow in multiplication" "" { target *-*-* } 102 }
// { dg-error "overflow in constant expression" "" { target *-*-* } 0 }
+// { dg-error "narrowing conversion" "" { target *-*-* } 0 }
// { dg-prune-output "out of range" }
// { dg-prune-output "not usable in a constant expression" }
base-commit: f364cdffa47af574f90f671b2dcf5afa91442741
--
2.31.1
