[libc++] Fix uses of non-empty transparent comparator in <map> (llvm#152624)

frederick-vs-ja · tru · commit c092e2af144d · 2025-08-11T14:10:52.000+02:00
The `__get_value()` member function was removed in LLVM 21, but the calls in `<map>` weren't removed. This patch completes the removal and adds regression test cases. Fixes llvm#152543. (cherry picked from commit 7ae1424)
diff --git a/libcxx/include/map b/libcxx/include/map
@@ -692,12 +692,12 @@ public:
 #  if _LIBCPP_STD_VER >= 14
   template <typename _K2>
   _LIBCPP_HIDE_FROM_ABI bool operator()(const _K2& __x, const _CP& __y) const {
-    return __comp_(__x, __y.__get_value().first);
+    return __comp_(__x, __y.first);
   }
 
   template <typename _K2>
   _LIBCPP_HIDE_FROM_ABI bool operator()(const _CP& __x, const _K2& __y) const {
-    return __comp_(__x.__get_value().first, __y);
+    return __comp_(__x.first, __y);
   }
 #  endif
 };
diff --git a/libcxx/test/std/containers/associative/map/map.ops/count0.pass.cpp b/libcxx/test/std/containers/associative/map/map.ops/count0.pass.cpp
@@ -33,6 +33,10 @@ int main(int, char**) {
     typedef std::map<int, double, transparent_less_not_referenceable> M;
     assert(M().count(C2Int{5}) == 0);
   }
+  {
+    using M = std::map<int, double, transparent_less_nonempty>;
+    assert(M().count(C2Int{5}) == 0);
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/map/map.ops/equal_range0.pass.cpp b/libcxx/test/std/containers/associative/map/map.ops/equal_range0.pass.cpp
@@ -40,6 +40,13 @@ int main(int, char**) {
     P result = example.equal_range(C2Int{5});
     assert(result.first == result.second);
   }
+  {
+    using M = std::map<int, double, transparent_less_nonempty>;
+    using P = std::pair<typename M::iterator, typename M::iterator>;
+    M example;
+    P result = example.equal_range(C2Int{5});
+    assert(result.first == result.second);
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/map/map.ops/find0.pass.cpp b/libcxx/test/std/containers/associative/map/map.ops/find0.pass.cpp
@@ -36,6 +36,11 @@ int main(int, char**) {
     M example;
     assert(example.find(C2Int{5}) == example.end());
   }
+  {
+    using M = std::map<int, double, transparent_less_nonempty>;
+    M example;
+    assert(example.find(C2Int{5}) == example.end());
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/map/map.ops/lower_bound0.pass.cpp b/libcxx/test/std/containers/associative/map/map.ops/lower_bound0.pass.cpp
@@ -36,6 +36,11 @@ int main(int, char**) {
     M example;
     assert(example.lower_bound(C2Int{5}) == example.end());
   }
+  {
+    using M = std::map<int, double, transparent_less_nonempty>;
+    M example;
+    assert(example.lower_bound(C2Int{5}) == example.end());
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/map/map.ops/upper_bound0.pass.cpp b/libcxx/test/std/containers/associative/map/map.ops/upper_bound0.pass.cpp
@@ -36,6 +36,11 @@ int main(int, char**) {
     M example;
     assert(example.upper_bound(C2Int{5}) == example.end());
   }
+  {
+    using M = std::map<int, double, transparent_less_nonempty>;
+    M example;
+    assert(example.upper_bound(C2Int{5}) == example.end());
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/multimap/multimap.ops/count0.pass.cpp b/libcxx/test/std/containers/associative/multimap/multimap.ops/count0.pass.cpp
@@ -33,6 +33,10 @@ int main(int, char**) {
     typedef std::multimap<int, double, transparent_less_not_referenceable> M;
     assert(M().count(C2Int{5}) == 0);
   }
+  {
+    using M = std::multimap<int, double, transparent_less_nonempty>;
+    assert(M().count(C2Int{5}) == 0);
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/multimap/multimap.ops/equal_range0.pass.cpp b/libcxx/test/std/containers/associative/multimap/multimap.ops/equal_range0.pass.cpp
@@ -40,6 +40,13 @@ int main(int, char**) {
     P result = example.equal_range(C2Int{5});
     assert(result.first == result.second);
   }
+  {
+    using M = std::multimap<int, double, transparent_less_nonempty>;
+    using P = std::pair<typename M::iterator, typename M::iterator>;
+    M example;
+    P result = example.equal_range(C2Int{5});
+    assert(result.first == result.second);
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/multimap/multimap.ops/find0.pass.cpp b/libcxx/test/std/containers/associative/multimap/multimap.ops/find0.pass.cpp
@@ -36,6 +36,11 @@ int main(int, char**) {
     M example;
     assert(example.find(C2Int{5}) == example.end());
   }
+  {
+    using M = std::multimap<int, double, transparent_less_nonempty>;
+    M example;
+    assert(example.find(C2Int{5}) == example.end());
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/multimap/multimap.ops/lower_bound0.pass.cpp b/libcxx/test/std/containers/associative/multimap/multimap.ops/lower_bound0.pass.cpp
@@ -36,6 +36,11 @@ int main(int, char**) {
     M example;
     assert(example.lower_bound(C2Int{5}) == example.end());
   }
+  {
+    using M = std::multimap<int, double, transparent_less_nonempty>;
+    M example;
+    assert(example.lower_bound(C2Int{5}) == example.end());
+  }
 
   return 0;
 }
diff --git a/libcxx/test/std/containers/associative/multimap/multimap.ops/upper_bound0.pass.cpp b/libcxx/test/std/containers/associative/multimap/multimap.ops/upper_bound0.pass.cpp
@@ -36,6 +36,11 @@ int main(int, char**) {
     M example;
     assert(example.upper_bound(C2Int{5}) == example.end());
   }
+  {
+    using M = std::multimap<int, double, transparent_less_nonempty>;
+    M example;
+    assert(example.upper_bound(C2Int{5}) == example.end());
+  }
 
   return 0;
 }
diff --git a/libcxx/test/support/is_transparent.h b/libcxx/test/support/is_transparent.h
@@ -36,6 +36,17 @@ struct transparent_less_not_referenceable
     using is_transparent = void () const &;  // it's a type; a weird one, but a type
 };
 
+// Prevent regression when empty base class optimization is not suitable.
+// See https://github.com/llvm/llvm-project/issues/152543.
+struct transparent_less_nonempty {
+  template <class T, class U>
+  constexpr bool operator()(T&& t, U&& u) const {
+    return std::forward<T>(t) < std::forward<U>(u);
+  }
+  struct is_transparent {
+  } pad_; // making this comparator non-empty
+};
+
 struct transparent_less_no_type
 {
     template <class T, class U>

Original file line number	Diff line number	Diff line change
`@@ -692,12 +692,12 @@ public:`
`692`	`692`	`# if _LIBCPP_STD_VER >= 14`
`693`	`693`	`template <typename _K2>`
`694`	`694`	`_LIBCPP_HIDE_FROM_ABI bool operator()(const _K2& __x, const _CP& __y) const {`
`695`		`- return __comp_(__x, __y.__get_value().first);`
	`695`	`+ return __comp_(__x, __y.first);`
`696`	`696`	`}`
`697`	`697`
`698`	`698`	`template <typename _K2>`
`699`	`699`	`_LIBCPP_HIDE_FROM_ABI bool operator()(const _CP& __x, const _K2& __y) const {`
`700`		`- return __comp_(__x.__get_value().first, __y);`
	`700`	`+ return __comp_(__x.first, __y);`
`701`	`701`	`}`
`702`	`702`	`# endif`
`703`	`703`	`};`
Original file line number	Diff line number	Diff line change
`@@ -33,6 +33,10 @@ int main(int, char**) {`
`33`	`33`	`typedef std::map<int, double, transparent_less_not_referenceable> M;`
`34`	`34`	`assert(M().count(C2Int{5}) == 0);`
`35`	`35`	`}`
	`36`	`+ {`
	`37`	`+ using M = std::map<int, double, transparent_less_nonempty>;`
	`38`	`+ assert(M().count(C2Int{5}) == 0);`
	`39`	`+ }`
`36`	`40`
`37`	`41`	`return 0;`
`38`	`42`	`}`
Original file line number	Diff line number	Diff line change
`@@ -40,6 +40,13 @@ int main(int, char**) {`
`40`	`40`	`P result = example.equal_range(C2Int{5});`
`41`	`41`	`assert(result.first == result.second);`
`42`	`42`	`}`
	`43`	`+ {`
	`44`	`+ using M = std::map<int, double, transparent_less_nonempty>;`
	`45`	`+ using P = std::pair<typename M::iterator, typename M::iterator>;`
	`46`	`+ M example;`
	`47`	`+ P result = example.equal_range(C2Int{5});`
	`48`	`+ assert(result.first == result.second);`
	`49`	`+ }`
`43`	`50`
`44`	`51`	`return 0;`
`45`	`52`	`}`
Original file line number	Diff line number	Diff line change
`@@ -36,6 +36,11 @@ int main(int, char**) {`
`36`	`36`	`M example;`
`37`	`37`	`assert(example.find(C2Int{5}) == example.end());`
`38`	`38`	`}`
	`39`	`+ {`
	`40`	`+ using M = std::map<int, double, transparent_less_nonempty>;`
	`41`	`+ M example;`
	`42`	`+ assert(example.find(C2Int{5}) == example.end());`
	`43`	`+ }`
`39`	`44`
`40`	`45`	`return 0;`
`41`	`46`	`}`