https://gcc.gnu.org/g:cfc9fa3bdddc1af59b7854937b99516067fd8c63
commit r15-1688-gcfc9fa3bdddc1af59b7854937b99516067fd8c63
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue Jun 18 20:57:13 2024 +0100
libstdc++: Enable more debug assertions during constant evaluation
[PR111250]
Some of our debug assertions expand to nothing unless
_GLIBCXX_ASSERTIONS is defined, which means they are not checked during
constant evaluation. By making them unconditionally expand to a
__glibcxx_assert expression they will be checked during constant
evaluation. This allows us to diagnose more instances of undefined
behaviour at compile-time, such as accessing a vector past-the-end.
libstdc++-v3/ChangeLog:
PR libstdc++/111250
* include/debug/assertions.h (__glibcxx_requires_non_empty_range)
(__glibcxx_requires_nonempty, __glibcxx_requires_subscript):
Define to __glibcxx_assert expressions or to debug mode
__glibcxx_check_xxx expressions.
* testsuite/23_containers/array/element_access/constexpr_c++17.cc:
Add checks for out-of-bounds accesses in constant expressions.
* testsuite/23_containers/vector/element_access/constexpr.cc:
Likewise.
Diff:
---
libstdc++-v3/include/debug/assertions.h | 14 ++++---
.../array/element_access/constexpr_c++17.cc | 44 ++++++++++++++++++++++
.../vector/element_access/constexpr.cc | 24 ++++++++++--
3 files changed, 72 insertions(+), 10 deletions(-)
diff --git a/libstdc++-v3/include/debug/assertions.h
b/libstdc++-v3/include/debug/assertions.h
index fff1ae8def0..20441e33897 100644
--- a/libstdc++-v3/include/debug/assertions.h
+++ b/libstdc++-v3/include/debug/assertions.h
@@ -31,12 +31,7 @@
#include <bits/c++config.h>
-#ifndef _GLIBCXX_ASSERTIONS
-# define __glibcxx_requires_non_empty_range(_First,_Last)
-# define __glibcxx_requires_nonempty()
-# define __glibcxx_requires_subscript(_N)
-#else
-
+#ifndef _GLIBCXX_DEBUG
// Verify that [_First, _Last) forms a non-empty iterator range.
# define __glibcxx_requires_non_empty_range(_First,_Last) \
__glibcxx_assert(_First != _Last)
@@ -45,6 +40,13 @@
// Verify that the container is nonempty
# define __glibcxx_requires_nonempty() \
__glibcxx_assert(!this->empty())
+#else // Use the more verbose Debug Mode checks.
+# define __glibcxx_requires_non_empty_range(_First,_Last) \
+ __glibcxx_check_non_empty_range(_First,_Last)
+# define __glibcxx_requires_nonempty() \
+ __glibcxx_check_nonempty()
+# define __glibcxx_requires_subscript(_N) \
+ __glibcxx_check_subscript(_N)
#endif
#if defined _GLIBCXX_DEBUG && _GLIBCXX_HOSTED
diff --git
a/libstdc++-v3/testsuite/23_containers/array/element_access/constexpr_c++17.cc
b/libstdc++-v3/testsuite/23_containers/array/element_access/constexpr_c++17.cc
index a14ad487b42..19ab1cc1f8e 100644
---
a/libstdc++-v3/testsuite/23_containers/array/element_access/constexpr_c++17.cc
+++
b/libstdc++-v3/testsuite/23_containers/array/element_access/constexpr_c++17.cc
@@ -66,3 +66,47 @@ constexpr bool test_zero()
}
static_assert( test_zero() );
+
+#ifdef __cpp_concepts
+template<typename T = int>
+ constexpr std::false_type
+ access_empty() { return {}; }
+
+template<typename T = int>
+ requires (std::bool_constant<&std::array<T, 0>{}.at(0) != nullptr>::value)
+ constexpr std::true_type
+ access_empty() { return {}; }
+
+template<typename T = int>
+ requires (std::bool_constant<&std::array<T, 0>{}[0] != nullptr>::value)
+ constexpr std::true_type
+ access_empty() { return {}; }
+
+template<typename T = int>
+ requires (std::bool_constant<&std::array<T, 0>{}.front() != nullptr>::value)
+ constexpr std::true_type
+ access_empty() { return {}; }
+
+template<typename T = int>
+ requires (std::bool_constant<&std::array<T, 0>{}.back() != nullptr>::value)
+ constexpr std::true_type
+ access_empty() { return {}; }
+
+static_assert( ! access_empty() );
+
+template<typename T = int>
+ constexpr std::false_type
+ access_past_the_end() { return {}; }
+
+template<typename T = int>
+ requires (std::bool_constant<std::array<T, 1>{}.at(0) != nullptr>::value)
+ constexpr std::true_type
+ access_past_the_end() { return {}; }
+
+template<typename T = int>
+ requires (std::bool_constant<&std::array<T, 1>{}[1] != nullptr>::value)
+ constexpr std::true_type
+ access_past_the_end() { return {}; }
+
+static_assert( ! access_past_the_end() );
+#endif
diff --git
a/libstdc++-v3/testsuite/23_containers/vector/element_access/constexpr.cc
b/libstdc++-v3/testsuite/23_containers/vector/element_access/constexpr.cc
index 19c91d28cd6..358ded47ad9 100644
--- a/libstdc++-v3/testsuite/23_containers/vector/element_access/constexpr.cc
+++ b/libstdc++-v3/testsuite/23_containers/vector/element_access/constexpr.cc
@@ -85,23 +85,39 @@ template<typename T = int>
access_empty() { return {}; }
template<typename T = int>
- requires (std::bool_constant<(std::vector<T>().at(0), true)>::value)
+ requires (std::bool_constant<&std::vector<T>().at(0) != nullptr>::value)
constexpr std::true_type
access_empty() { return {}; }
template<typename T = int>
- requires (std::bool_constant<(std::vector<T>()[0], true)>::value)
+ requires (std::bool_constant<&std::vector<T>()[0] != nullptr>::value)
constexpr std::true_type
access_empty() { return {}; }
template<typename T = int>
- requires (std::bool_constant<(std::vector<T>().front(), true)>::value)
+ requires (std::bool_constant<&std::vector<T>().front() != nullptr>::value)
constexpr std::true_type
access_empty() { return {}; }
template<typename T = int>
- requires (std::bool_constant<(std::vector<T>().back(), true)>::value)
+ requires (std::bool_constant<&std::vector<T>().back() != nullptr>::value)
constexpr std::true_type
access_empty() { return {}; }
static_assert( ! access_empty() );
+
+template<typename T = int>
+ constexpr std::false_type
+ access_past_the_end() { return {}; }
+
+template<typename T = int>
+ requires (std::bool_constant<&std::vector<T>(3).at(3) != nullptr>::value)
+ constexpr std::true_type
+ access_past_the_end() { return {}; }
+
+template<typename T = int>
+ requires (std::bool_constant<&std::vector<T>(3)[3] != nullptr>::value)
+ constexpr std::true_type
+ access_past_the_end() { return {}; }
+
+static_assert( ! access_past_the_end() );
