The immediate issue here was that the second warning didn't depend on the
first one, so if the first location was in a system header, we'd
mysteriously give the second by itself.
It's also the case that the thing we care about being in a system header is
the function that we want to suggest adding 'noexcept' to, not the
noexcept-expression; it's useful to suggest adding noexcept to a user
function to satisfy a noexcept-expression in a system header.
Tested x86_64-pc-linux-gnu, applying to trunk.
PR c++/90992
* except.c (maybe_noexcept_warning): Check DECL_IN_SYSTEM_HEADER and
temporarily enable -Wsystem-headers. Change second warning to
conditional inform.
---
gcc/testsuite/g++.dg/warn/Wnoexcept1.h | 37 ++++++++++++++++++++++++++
gcc/cp/except.c | 16 ++++++-----
gcc/testsuite/g++.dg/warn/Wnoexcept1.C | 34 +++++++++++++++++++++++
3 files changed, 81 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/Wnoexcept1.h
create mode 100644 gcc/testsuite/g++.dg/warn/Wnoexcept1.C
diff --git a/gcc/testsuite/g++.dg/warn/Wnoexcept1.h
b/gcc/testsuite/g++.dg/warn/Wnoexcept1.h
new file mode 100644
index 00000000000..f59733e705f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wnoexcept1.h
@@ -0,0 +1,37 @@
+// -*- C++ -*-
+#pragma GCC system_header
+
+using size_t = decltype(sizeof(42));
+inline void * operator new (size_t, void *p) noexcept { return p; }
+
+class NotNoexcept {
+public:
+ NotNoexcept() noexcept(false) {}
+ NotNoexcept(const NotNoexcept&) noexcept(false) {}
+ NotNoexcept(NotNoexcept &&) noexcept(false) {}
+ ~NotNoexcept() noexcept(false) {}
+
+ NotNoexcept&operator=(const NotNoexcept&) noexcept(false) { return *this;}
+ NotNoexcept&operator=(NotNoexcept &&) noexcept(false) {return *this;}
+};
+
+template<typename _Up, typename... _Args>
+void
+construct1(_Up* __p, _Args... __args)
+ noexcept(noexcept(::new((void *)__p) _Up(__args...)))
+{ ::new((void *)__p) _Up(__args...); }
+
+template<typename _Up, typename... _Args>
+void
+construct2(_Up* __p, _Args... __args)
+ noexcept(noexcept(::new((void *)__p) _Up(__args...)))
+{ ::new((void *)__p) _Up(__args...); }
+
+class Automatic1 {
+public:
+ Automatic1(size_t bla) : Bla(bla) {};
+
+private:
+ size_t Bla;
+ NotNoexcept Dummy;
+};
diff --git a/gcc/cp/except.c b/gcc/cp/except.c
index 0b40234e228..788b96de243 100644
--- a/gcc/cp/except.c
+++ b/gcc/cp/except.c
@@ -1165,13 +1165,17 @@ static GTY(()) vec<pending_noexcept, va_gc>
*pending_noexcept_checks;
static void
maybe_noexcept_warning (tree fn)
{
- if (TREE_NOTHROW (fn))
+ if (TREE_NOTHROW (fn)
+ && (!DECL_IN_SYSTEM_HEADER (fn)
+ || global_dc->dc_warn_system_headers))
{
- warning (OPT_Wnoexcept, "noexcept-expression evaluates to %<false%> "
- "because of a call to %qD", fn);
- warning_at (DECL_SOURCE_LOCATION (fn), OPT_Wnoexcept,
- "but %qD does not throw; perhaps "
- "it should be declared %<noexcept%>", fn);
+ temp_override<bool> s (global_dc->dc_warn_system_headers, true);
+ auto_diagnostic_group d;
+ if (warning (OPT_Wnoexcept, "noexcept-expression evaluates to %<false%> "
+ "because of a call to %qD", fn))
+ inform (DECL_SOURCE_LOCATION (fn),
+ "but %qD does not throw; perhaps "
+ "it should be declared %<noexcept%>", fn);
}
}
diff --git a/gcc/testsuite/g++.dg/warn/Wnoexcept1.C
b/gcc/testsuite/g++.dg/warn/Wnoexcept1.C
new file mode 100644
index 00000000000..e3a5df64459
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wnoexcept1.C
@@ -0,0 +1,34 @@
+// PR c++/90992
+// { dg-do compile { target c++11 } }
+// { dg-additional-options -Wnoexcept }
+
+#include "Wnoexcept1.h"
+
+// We expect a warning at the declaration of construct2, since Automatic2 is
+// defined below; we don't expect one for construct1, because Automatic1 is
+// defined in the fake system header.
+// { dg-warning "noexcept-expression" "" { target *-*-* } 26 }
+
+class Automatic2 {
+public:
+ Automatic2(size_t bla) : Bla(bla) {}; // { dg-message "noexcept" }
+
+private:
+ size_t Bla;
+ NotNoexcept Dummy;
+};
+
+union U
+{
+ unsigned char buf[sizeof(Automatic1)];
+ Automatic1 a1;
+ Automatic2 a2;
+ U(): buf{} {}
+ ~U() {}
+};
+
+int main() {
+ U u;
+ construct1(&u.a1, 42);
+ construct2(&u.a2, 42);
+}
base-commit: cf17dcc6fc1f9f69d592952c2dd5796a5665bd5a
--
2.18.1
