From 75df481fcc381d6aaefdbe2ef1d66927e30b5743 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 21 Mar 2025 22:49:44 +0000
Subject: [PATCH] libstdc++: Ensure that std::vector<bool> allocator has bool
 value_type
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This is the subject of LWG 4228 which notes that libstdc++ doesn't
enforce this requirement. That's just a bug because I forgot to add it
to vector<bool> when adding it elsewhere.

For consistency with the other containers we should not allow incorrect
allocator types for strict -std=c++NN modes, but it is very late to make
that change for GCC 15 so this only enables the assertion for C++20
(where it's required). For GCC 16 we can enable it for strict modes too.

libstdc++-v3/ChangeLog:

	* include/bits/stl_bvector.h (vector<bool, A>): Enforce the
	C++20 requirement that the allocator's value_type matches the
	container.
	* testsuite/23_containers/vector/bool/cons/from_range.cc: Fix
	incorrect allocator type.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
---
 libstdc++-v3/include/bits/stl_bvector.h                       | 4 ++++
 .../testsuite/23_containers/vector/bool/cons/from_range.cc    | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/bits/stl_bvector.h b/libstdc++-v3/include/bits/stl_bvector.h
index 2292eec54ad..3ee15eaa938 100644
--- a/libstdc++-v3/include/bits/stl_bvector.h
+++ b/libstdc++-v3/include/bits/stl_bvector.h
@@ -751,6 +751,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 
 #if __cplusplus >= 201103L
       friend struct std::hash<vector>;
+# if __cplusplus > 201703L // || defined __STRICT_ANSI__
+      static_assert(is_same<typename _Alloc::value_type, bool>::value,
+	  "std::vector must have the same value_type as its allocator");
+# endif
 #endif
 
     public:
diff --git a/libstdc++-v3/testsuite/23_containers/vector/bool/cons/from_range.cc b/libstdc++-v3/testsuite/23_containers/vector/bool/cons/from_range.cc
index f531e7f5039..37f0ecf32ad 100644
--- a/libstdc++-v3/testsuite/23_containers/vector/bool/cons/from_range.cc
+++ b/libstdc++-v3/testsuite/23_containers/vector/bool/cons/from_range.cc
@@ -71,7 +71,7 @@ test_ranges()
     bool val;
   };
   using rvalue_input_range = test_range<C, input_iterator_wrapper_rval>;
-  do_test<rvalue_input_range>(std::allocator<int>());
+  do_test<rvalue_input_range>(std::allocator<bool>());
 
   return true;
 }