diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -862,7 +862,10 @@
         export locale
       }
       module format_error                    { private header "__format/format_error.h" }
-      module format_functions                { private header "__format/format_functions.h" }
+      module format_functions                {
+        private header "__format/format_functions.h"
+        export string
+      }
       module format_fwd                      { private header "__format/format_fwd.h" }
       module format_parse_context            { private header "__format/format_parse_context.h" }
       module format_string                   { private header "__format/format_string.h" }
diff --git a/libcxx/test/libcxx/utilities/format/format.formatter/format.context/types.compile.pass.cpp b/libcxx/test/libcxx/utilities/format/format.formatter/format.context/types.compile.pass.cpp
--- a/libcxx/test/libcxx/utilities/format/format.formatter/format.context/types.compile.pass.cpp
+++ b/libcxx/test/libcxx/utilities/format/format.formatter/format.context/types.compile.pass.cpp
@@ -24,6 +24,7 @@
 // using wformat_context = basic_format_context<unspecified, wchar_t>;
 
 #include <format>
+#include <iterator>
 #include <string_view>
 #include <type_traits>
 
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.sh.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.sh.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.sh.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.sh.cpp
@@ -19,6 +19,7 @@
 // - otherwise, if T is char and char_type is wchar_t, initializes value with static_cast<wchar_t>(v);
 
 #include <format>
+#include <iterator>
 #include <string>
 
 void test() {
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
@@ -16,6 +16,7 @@
 // template<class Visitor, class Context>
 //   see below visit_format_arg(Visitor&& vis, basic_format_arg<Context> arg);
 
+#include <algorithm>
 #include <format>
 #include <cassert>
 #include <type_traits>
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/arg.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/arg.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/arg.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/arg.pass.cpp
@@ -13,6 +13,7 @@
 // basic_format_arg<basic_format_context> arg(size_t id) const;
 
 #include <format>
+#include <iterator>
 #include <cassert>
 
 #include "test_basic_format_arg.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/ctor.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/ctor.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/ctor.pass.cpp
@@ -24,6 +24,7 @@
 
 #include <format>
 #include <cassert>
+#include <iterator>
 #include <type_traits>
 
 #include "test_basic_format_arg.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/locale.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/locale.pass.cpp
@@ -17,6 +17,7 @@
 // std::locale locale();
 
 #include <format>
+#include <iterator>
 #include <cassert>
 
 #include "make_string.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.handle.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.handle.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.handle.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.handle.pass.cpp
@@ -21,6 +21,7 @@
 #include <cmath>
 #include <charconv>
 #include <concepts>
+#include <iterator>
 #include <string>
 #include <type_traits>
 
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.bool.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.bool.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.bool.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.bool.pass.cpp
@@ -22,6 +22,7 @@
 #include <format>
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <type_traits>
 
 #include "test_format_context.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.c_string.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.c_string.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.c_string.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.c_string.pass.cpp
@@ -21,6 +21,7 @@
 #include <format>
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <type_traits>
 
 #include "test_format_context.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char.pass.cpp
@@ -22,6 +22,7 @@
 #include <format>
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <type_traits>
 
 #include "test_format_context.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp
@@ -21,6 +21,7 @@
 #include <format>
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <type_traits>
 
 #include "test_format_context.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.const_char_array.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.const_char_array.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.const_char_array.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.const_char_array.pass.cpp
@@ -22,6 +22,7 @@
 #include <format>
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <type_traits>
 
 #include "test_format_context.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.floating_point.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.floating_point.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.floating_point.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.floating_point.pass.cpp
@@ -31,6 +31,7 @@
 #include <cmath>
 #include <charconv>
 #include <concepts>
+#include <iterator>
 #include <string>
 #include <type_traits>
 
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.pointer.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.pointer.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.pointer.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.pointer.pass.cpp
@@ -26,6 +26,7 @@
 #include <cmath>
 #include <charconv>
 #include <concepts>
+#include <iterator>
 #include <string>
 #include <type_traits>
 
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.signed_integral.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.signed_integral.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.signed_integral.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.signed_integral.pass.cpp
@@ -29,6 +29,7 @@
 #include <format>
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <type_traits>
 
 #include "test_format_context.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.string.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.string.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.string.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.string.pass.cpp
@@ -23,6 +23,7 @@
 #include <format>
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <type_traits>
 
 #include "make_string.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.unsigned_integral.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.unsigned_integral.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.unsigned_integral.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.unsigned_integral.pass.cpp
@@ -29,6 +29,7 @@
 #include <format>
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <type_traits>
 
 #include "test_format_context.h"
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.pass.cpp
@@ -19,6 +19,7 @@
 #include <format>
 
 #include <cassert>
+#include <cstring>
 #include <string_view>
 
 #include "test_macros.h"
@@ -39,8 +40,7 @@
       context.check_arg_id(0);
       assert(false);
     } catch ([[maybe_unused]] const std::format_error& e) {
-      LIBCPP_ASSERT(strcmp(e.what(), "Using manual argument numbering in automatic "
-                                     "argument numbering mode") == 0);
+      LIBCPP_ASSERT(std::strcmp(e.what(), "Using manual argument numbering in automatic argument numbering mode") == 0);
       return;
     }
     assert(false);
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/next_arg_id.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/next_arg_id.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/next_arg_id.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/next_arg_id.pass.cpp
@@ -19,6 +19,7 @@
 #include <format>
 
 #include <cassert>
+#include <cstring>
 #include <string_view>
 
 #include "test_macros.h"
@@ -39,8 +40,7 @@
     TEST_IGNORE_NODISCARD context.next_arg_id();
     assert(false);
   } catch ([[maybe_unused]] const std::format_error& e) {
-    LIBCPP_ASSERT(strcmp(e.what(), "Using automatic argument numbering in manual "
-                                   "argument numbering mode") == 0);
+    LIBCPP_ASSERT(std::strcmp(e.what(), "Using automatic argument numbering in manual argument numbering mode") == 0);
     return;
   }
   assert(false);
diff --git a/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp b/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
@@ -18,6 +18,7 @@
 
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <list>
 #include <vector>
 
diff --git a/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp b/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
@@ -24,6 +24,7 @@
 
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <list>
 #include <vector>
 
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format_to.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to.locale.pass.cpp
@@ -23,6 +23,7 @@
 #include <format>
 #include <algorithm>
 #include <cassert>
+#include <iterator>
 #include <list>
 #include <vector>
 
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp
@@ -20,6 +20,7 @@
 #include <format>
 #include <algorithm>
 #include <cassert>
+#include <iterator>
 #include <list>
 #include <vector>
 
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to_n.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format_to_n.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to_n.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to_n.pass.cpp
@@ -22,6 +22,7 @@
 #include <format>
 #include <algorithm>
 #include <cassert>
+#include <iterator>
 #include <list>
 #include <vector>
 
diff --git a/libcxx/test/std/utilities/format/format.range/format.range.fmtmap/format.pass.cpp b/libcxx/test/std/utilities/format/format.range/format.range.fmtmap/format.pass.cpp
--- a/libcxx/test/std/utilities/format/format.range/format.range.fmtmap/format.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.range/format.range.fmtmap/format.pass.cpp
@@ -30,6 +30,7 @@
 #include <cassert>
 #include <concepts>
 #include <format>
+#include <iterator>
 #include <map>
 
 #include "test_format_context.h"
diff --git a/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.pass.cpp b/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.pass.cpp
--- a/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.pass.cpp
@@ -26,6 +26,7 @@
 
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <format>
 #include <set>
 
diff --git a/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h b/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h
--- a/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h
+++ b/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h
@@ -17,6 +17,7 @@
 #include <list>
 #include <ranges>
 #include <span>
+#include <tuple>
 #include <vector>
 
 #include "format.functions.common.h"
diff --git a/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.pass.cpp b/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.pass.cpp
--- a/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.range/format.range.formatter/format.pass.cpp
@@ -30,6 +30,7 @@
 
 #include <cassert>
 #include <concepts>
+#include <iterator>
 #include <format>
 #include <vector>
 
diff --git a/libcxx/test/std/utilities/format/format.range/format.range.formatter/set_brackets.pass.cpp b/libcxx/test/std/utilities/format/format.range/format.range.formatter/set_brackets.pass.cpp
--- a/libcxx/test/std/utilities/format/format.range/format.range.formatter/set_brackets.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.range/format.range.formatter/set_brackets.pass.cpp
@@ -29,6 +29,7 @@
 
 #include <format>
 #include <cassert>
+#include <iterator>
 #include <type_traits>
 #include <vector>
 
diff --git a/libcxx/test/std/utilities/format/format.range/format.range.formatter/set_separator.pass.cpp b/libcxx/test/std/utilities/format/format.range/format.range.formatter/set_separator.pass.cpp
--- a/libcxx/test/std/utilities/format/format.range/format.range.formatter/set_separator.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.range/format.range.formatter/set_separator.pass.cpp
@@ -28,6 +28,7 @@
 
 #include <format>
 #include <cassert>
+#include <iterator>
 #include <type_traits>
 #include <vector>
 
diff --git a/libcxx/test/std/utilities/format/format.syn/format_to_n_result.pass.cpp b/libcxx/test/std/utilities/format/format.syn/format_to_n_result.pass.cpp
--- a/libcxx/test/std/utilities/format/format.syn/format_to_n_result.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.syn/format_to_n_result.pass.cpp
@@ -22,6 +22,7 @@
 
 #include <cassert>
 #include <concepts>
+#include <iterator>
 
 #include "test_macros.h"
 
diff --git a/libcxx/test/std/utilities/format/format.tuple/format.functions.tests.h b/libcxx/test/std/utilities/format/format.tuple/format.functions.tests.h
--- a/libcxx/test/std/utilities/format/format.tuple/format.functions.tests.h
+++ b/libcxx/test/std/utilities/format/format.tuple/format.functions.tests.h
@@ -10,6 +10,7 @@
 
 #include <concepts>
 #include <format>
+#include <tuple>
 
 #include "format.functions.common.h"
 
diff --git a/libcxx/test/std/utilities/format/format.tuple/format.pass.cpp b/libcxx/test/std/utilities/format/format.tuple/format.pass.cpp
--- a/libcxx/test/std/utilities/format/format.tuple/format.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.tuple/format.pass.cpp
@@ -30,6 +30,7 @@
 #include <cassert>
 #include <concepts>
 #include <format>
+#include <iterator>
 #include <tuple>
 #include <utility>