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* [gcc r13-4615] libstdc++: Add a test checking for chrono::duration overflows
@ 2022-12-12 14:01 Jonathan Wakely
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From: Jonathan Wakely @ 2022-12-12 14:01 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:dc94eaab008165698a1161c757db96fc701103a2
commit r13-4615-gdc94eaab008165698a1161c757db96fc701103a2
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Dec 12 12:51:49 2022 +0000
libstdc++: Add a test checking for chrono::duration overflows
This test fails if chrono::days::rep or chrono::years::rep is a 32-bit
type, because a large days or years value silently overflows a 32-bit
integer when converted to seconds. It would be conforming to implement
chrono::days as chrono::duration<int32_t, ratio<86400>>, but would make
this overflow case more likely. Similarly for chrono::years,
chrono::months and chrono::weeks. This test is here to remind us not to
make that change lightly.
libstdc++-v3/ChangeLog:
* testsuite/20_util/duration/arithmetic/overflow_c++20.cc: New
test.
Diff:
---
.../20_util/duration/arithmetic/overflow_c++20.cc | 29 ++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/libstdc++-v3/testsuite/20_util/duration/arithmetic/overflow_c++20.cc b/libstdc++-v3/testsuite/20_util/duration/arithmetic/overflow_c++20.cc
new file mode 100644
index 00000000000..42fa7ea55fb
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/duration/arithmetic/overflow_c++20.cc
@@ -0,0 +1,29 @@
+// { dg-options "-std=gnu++20" }
+// { dg-do run { target c++20 } }
+
+#include <chrono>
+#include <cstdint>
+#include <testsuite_hooks.h>
+
+void
+test_overflow()
+{
+ using namespace std::chrono;
+
+ using seconds32_t = duration<std::int_least32_t>;
+ seconds32_t t = 14h + 25min + 55s;
+ auto snow = sys_days(1854y/December/11);
+ auto snow_t = snow + t;
+ // Fails if days::rep is 32-bit:
+ VERIFY( snow_t.time_since_epoch() < seconds::zero() );
+ auto y = floor<years>(snow);
+ auto y_t = y + t;
+ // Fails if years::rep is 32-bit:
+ VERIFY( y_t.time_since_epoch() < seconds::zero() );
+ VERIFY( y_t < snow_t );
+}
+
+int main()
+{
+ test_overflow();
+}
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