Update std.cppm to Clang 18, add std.compat.cppm

Note that Clang 17 is not longer supported with regards to standard
library modules.

4 files changed, 1087 insertions, 80 deletions

diff --git a/libbuild2/cc/buildfile b/libbuild2/cc/buildfile
index 654d0a4..05e4c8c 100644
--- a/libbuild2/cc/buildfile
+++ b/libbuild2/cc/buildfile
@@ -25,14 +25,14 @@ libul{build2-cc}: cxx{pkgconfig-libpkg-config}: include = (!$libpkgconf)
 
 libul{build2-cc}: $intf_libs $impl_libs
 
-# libc++ std module interface translation unit.
+# libc++ std module interface translation units.
 #
 # Hopefully temporary, see llvm-project GH issues #73089.
 #
 # @@ TMP: make sure sync'ed with upstream before release (keep this note).
 #
-lib{build2-cc}: file{std.cppm}
-file{std.cppm}@./: install = data/libbuild2/cc/
+lib{build2-cc}: file{std.cppm std.compat.cppm}
+file{std.cppm}@./ file{std.compat.cppm}@./: install = data/libbuild2/cc/
 
 # Unit tests.
 #
diff --git a/libbuild2/cc/compile-rule.cxx b/libbuild2/cc/compile-rule.cxx
index 2e4775e..1548395 100644
--- a/libbuild2/cc/compile-rule.cxx
+++ b/libbuild2/cc/compile-rule.cxx
@@ -6157,7 +6157,7 @@ namespace build2
       //
       if ((ctype == compiler_type::msvc)          ||
           (ctype == compiler_type::clang &&
-           cmaj >= 17                    &&
+           cmaj >= 18                    &&
            cast<string> (rs[x_stdlib]) == "libc++"))
       {
         // Similar logic to check_exact() above.
@@ -6177,10 +6177,7 @@ namespace build2
             {
             case compiler_type::clang:
               {
-                if (m.name != "std")
-                  fail << "module " << m.name << " not yet provided by libc++";
-
-                // Find or insert std.cppm (similar code to pkgconfig.cxx).
+                // Find or insert std*.cppm (similar code to pkgconfig.cxx).
                 //
                 // Note: build_install_data is absolute and normalized.
                 //
@@ -6188,7 +6185,7 @@ namespace build2
                   *x_mod,
                   (dir_path (build_install_data) /= "libbuild2") /= "cc",
                   dir_path (),
-                  "std",
+                  m.name,
                   string ("cppm"), // For C++14 during bootstrap.
                   target_decl::implied,
                   trace).first;
@@ -6199,18 +6196,18 @@ namespace build2
                 // type. And we could do that by looking for -static-libstdc++
                 // in loption (and no, it's not -static-libc++).
                 //
-                // But, looking at the object file produced from std.cppm, it
-                // only contains one symbol, the static object initializer.
-                // And this is unlikely to change since all other non-inline
-                // or template symbols should be in libc++. So feels like it's
-                // not worth the trouble and one variant should be good enough
-                // for both cases. Let's use the shared one for less
-                // surprising diagnostics (as in, "why are you linking obje{}
-                // to a shared library?")
+                // But, looking at the object file produced from std*.cppm,
+                // they only contain one symbol, the static object
+                // initializer. And this is unlikely to change since all
+                // other non-inline or template symbols should be in
+                // libc++. So feels like it's not worth the trouble and one
+                // variant should be good enough for both cases. Let's use the
+                // shared one for less surprising diagnostics (as in, "why are
+                // you linking obje{} to a shared library?")
                 //
-                // (Of course, theoretically, std.cppm could detect via a
-                // macro whether it's being compiled with -fPIC or not and do
-                // things differently, but this seems far-fetched).
+                // (Of course, theoretically, std*.cppm could detect via a
+                // macro whether they are being compiled with -fPIC or not and
+                // do things differently, but this seems far-fetched).
                 //
                 ot = otype::s;
 
diff --git a/libbuild2/cc/std.compat.cppm b/libbuild2/cc/std.compat.cppm
new file mode 100644
index 0000000..2668b30
--- /dev/null
+++ b/libbuild2/cc/std.compat.cppm
@@ -0,0 +1,996 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// WARNING, this entire header is generated by
+// utils/generate_libcxx_cppm_in.py
+// DO NOT MODIFY!
+
+module;
+
+#include <__config>
+
+#if _LIBCPP_VERSION < 180000
+#error libc++ version 18.0.0 or later required
+#endif
+
+// The headers of Table 24: C++ library headers [tab:headers.cpp]
+// and the headers of Table 25: C++ headers for C library facilities [tab:headers.cpp.c]
+#include <cassert>
+#include <cctype>
+#include <cerrno>
+#include <cfenv>
+#include <cfloat>
+#include <cinttypes>
+#include <climits>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#  include <clocale>
+#endif
+#include <cmath>
+#include <csetjmp>
+#include <csignal>
+#include <cstdarg>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <ctime>
+#include <cuchar>
+#if !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
+#  include <cwchar>
+#endif
+#if !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
+#  include <cwctype>
+#endif
+
+#if 0
+// *** Headers not yet available ***
+#if __has_include(<debugging>)
+#  error "please update the header information for <debugging> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<debugging>)
+#if __has_include(<flat_map>)
+#  error "please update the header information for <flat_map> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<flat_map>)
+#if __has_include(<flat_set>)
+#  error "please update the header information for <flat_set> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<flat_set>)
+#if __has_include(<generator>)
+#  error "please update the header information for <generator> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<generator>)
+#if __has_include(<hazard_pointer>)
+#  error "please update the header information for <hazard_pointer> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<hazard_pointer>)
+#if __has_include(<linalg>)
+#  error "please update the header information for <linalg> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<linalg>)
+#if __has_include(<rcu>)
+#  error "please update the header information for <rcu> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<rcu>)
+#if __has_include(<spanstream>)
+#  error "please update the header information for <spanstream> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<spanstream>)
+#if __has_include(<stacktrace>)
+#  error "please update the header information for <stacktrace> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<stacktrace>)
+#if __has_include(<stdfloat>)
+#  error "please update the header information for <stdfloat> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<stdfloat>)
+#if __has_include(<text_encoding>)
+#  error "please update the header information for <text_encoding> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<text_encoding>)
+#endif
+
+export module std.compat;
+export import std;
+
+// cassert.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  // This module exports nothing.
+} // export
+
+// cctype.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::isalnum;
+  using ::isalpha;
+  using ::isblank;
+  using ::iscntrl;
+  using ::isdigit;
+  using ::isgraph;
+  using ::islower;
+  using ::isprint;
+  using ::ispunct;
+  using ::isspace;
+  using ::isupper;
+  using ::isxdigit;
+  using ::tolower;
+  using ::toupper;
+} // export
+
+// cerrno.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  // This module exports nothing.
+} // export
+
+// cfenv.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  // types
+  using ::fenv_t;
+  using ::fexcept_t;
+
+  // functions
+  using ::feclearexcept;
+  using ::fegetexceptflag;
+  using ::feraiseexcept;
+  using ::fesetexceptflag;
+  using ::fetestexcept;
+
+  using ::fegetround;
+  using ::fesetround;
+
+  using ::fegetenv;
+  using ::feholdexcept;
+  using ::fesetenv;
+  using ::feupdateenv;
+} // export
+
+// cfloat.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  // This module exports nothing.
+} // export
+
+// cinttypes.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::imaxdiv_t;
+
+  using ::imaxabs;
+  using ::imaxdiv;
+  using ::strtoimax;
+  using ::strtoumax;
+  using ::wcstoimax;
+  using ::wcstoumax;
+
+  // abs is conditionally here, but always present in cmath.cppm. To avoid
+  // conflicing declarations omit the using here.
+
+  // div is conditionally here, but always present in cstdlib.cppm. To avoid
+  // conflicing declarations omit the using here.
+} // export
+
+// climits.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  // This module exports nothing.
+} // export
+
+// clocale.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+#ifndef _LIBCPP_HAS_NO_LOCALIZATION
+  using ::lconv;
+
+  using ::localeconv;
+  using ::setlocale;
+#endif // _LIBCPP_HAS_NO_LOCALIZATION
+} // export
+
+// cmath.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::double_t;
+  using ::float_t;
+
+  using ::acos;
+  using ::acosf;
+  using ::acosl;
+
+  using ::asin;
+  using ::asinf;
+  using ::asinl;
+
+  using ::atan;
+  using ::atanf;
+  using ::atanl;
+
+  using ::atan2;
+  using ::atan2f;
+  using ::atan2l;
+
+  using ::cos;
+  using ::cosf;
+  using ::cosl;
+
+  using ::sin;
+  using ::sinf;
+  using ::sinl;
+
+  using ::tan;
+  using ::tanf;
+  using ::tanl;
+
+  using ::acosh;
+  using ::acoshf;
+  using ::acoshl;
+
+  using ::asinh;
+  using ::asinhf;
+  using ::asinhl;
+
+  using ::atanh;
+  using ::atanhf;
+  using ::atanhl;
+
+  using ::cosh;
+  using ::coshf;
+  using ::coshl;
+
+  using ::sinh;
+  using ::sinhf;
+  using ::sinhl;
+
+  using ::tanh;
+  using ::tanhf;
+  using ::tanhl;
+
+  using ::exp;
+  using ::expf;
+  using ::expl;
+
+  using ::exp2;
+  using ::exp2f;
+  using ::exp2l;
+
+  using ::expm1;
+  using ::expm1f;
+  using ::expm1l;
+
+  using ::frexp;
+  using ::frexpf;
+  using ::frexpl;
+
+  using ::ilogb;
+  using ::ilogbf;
+  using ::ilogbl;
+
+  using ::ldexp;
+  using ::ldexpf;
+  using ::ldexpl;
+
+  using ::log;
+  using ::logf;
+  using ::logl;
+
+  using ::log10;
+  using ::log10f;
+  using ::log10l;
+
+  using ::log1p;
+  using ::log1pf;
+  using ::log1pl;
+
+  using ::log2;
+  using ::log2f;
+  using ::log2l;
+
+  using ::logb;
+  using ::logbf;
+  using ::logbl;
+
+  using ::modf;
+  using ::modff;
+  using ::modfl;
+
+  using ::scalbn;
+  using ::scalbnf;
+  using ::scalbnl;
+
+  using ::scalbln;
+  using ::scalblnf;
+  using ::scalblnl;
+
+  using ::cbrt;
+  using ::cbrtf;
+  using ::cbrtl;
+
+  // [c.math.abs], absolute values
+  using ::abs;
+
+  using ::fabs;
+  using ::fabsf;
+  using ::fabsl;
+
+  using ::hypot;
+  using ::hypotf;
+  using ::hypotl;
+
+  // [c.math.hypot3], three-dimensional hypotenuse
+
+  using ::pow;
+  using ::powf;
+  using ::powl;
+
+  using ::sqrt;
+  using ::sqrtf;
+  using ::sqrtl;
+
+  using ::erf;
+  using ::erff;
+  using ::erfl;
+
+  using ::erfc;
+  using ::erfcf;
+  using ::erfcl;
+
+  using ::lgamma;
+  using ::lgammaf;
+  using ::lgammal;
+
+  using ::tgamma;
+  using ::tgammaf;
+  using ::tgammal;
+
+  using ::ceil;
+  using ::ceilf;
+  using ::ceill;
+
+  using ::floor;
+  using ::floorf;
+  using ::floorl;
+
+  using ::nearbyint;
+  using ::nearbyintf;
+  using ::nearbyintl;
+
+  using ::rint;
+  using ::rintf;
+  using ::rintl;
+
+  using ::lrint;
+  using ::lrintf;
+  using ::lrintl;
+
+  using ::llrint;
+  using ::llrintf;
+  using ::llrintl;
+
+  using ::round;
+  using ::roundf;
+  using ::roundl;
+
+  using ::lround;
+  using ::lroundf;
+  using ::lroundl;
+
+  using ::llround;
+  using ::llroundf;
+  using ::llroundl;
+
+  using ::trunc;
+  using ::truncf;
+  using ::truncl;
+
+  using ::fmod;
+  using ::fmodf;
+  using ::fmodl;
+
+  using ::remainder;
+  using ::remainderf;
+  using ::remainderl;
+
+  using ::remquo;
+  using ::remquof;
+  using ::remquol;
+
+  using ::copysign;
+  using ::copysignf;
+  using ::copysignl;
+
+  using ::nan;
+  using ::nanf;
+  using ::nanl;
+
+  using ::nextafter;
+  using ::nextafterf;
+  using ::nextafterl;
+
+  using ::nexttoward;
+  using ::nexttowardf;
+  using ::nexttowardl;
+
+  using ::fdim;
+  using ::fdimf;
+  using ::fdiml;
+
+  using ::fmax;
+  using ::fmaxf;
+  using ::fmaxl;
+
+  using ::fmin;
+  using ::fminf;
+  using ::fminl;
+
+  using ::fma;
+  using ::fmaf;
+  using ::fmal;
+
+  // [c.math.lerp], linear interpolation
+  // [support.c.headers.other]/1
+  // ...  placed within the global namespace scope, except for the functions
+  // described in [sf.cmath], the std::lerp function overloads ([c.math.lerp])
+  // ...
+
+  // [c.math.fpclass], classification / comparison functions
+  using ::fpclassify;
+  using ::isfinite;
+  using ::isgreater;
+  using ::isgreaterequal;
+  using ::isinf;
+  using ::isless;
+  using ::islessequal;
+  using ::islessgreater;
+  using ::isnan;
+  using ::isnormal;
+  using ::isunordered;
+  using ::signbit;
+
+  // [sf.cmath], mathematical special functions
+} // export
+
+// csetjmp.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::jmp_buf;
+  using ::longjmp;
+} // export
+
+// csignal.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::sig_atomic_t;
+
+  // [support.signal], signal handlers
+  using ::signal;
+
+  using ::raise;
+} // export
+
+// cstdarg.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export { using ::va_list; } // export
+
+// cstddef.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::max_align_t;
+  using ::nullptr_t;
+  using ::ptrdiff_t;
+  using ::size_t;
+
+  // [support.c.headers]/1
+  // ...  placed within the global namespace scope, except for ... the
+  // declaration of std::byte ([cstddef.syn]), and the functions and
+  // function templates described in [support.types.byteops]. ...
+
+  // [support.types.byteops], byte type operations
+} // export
+
+// cstdint.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  // signed
+  using ::int8_t _LIBCPP_USING_IF_EXISTS;
+  using ::int16_t _LIBCPP_USING_IF_EXISTS;
+  using ::int32_t _LIBCPP_USING_IF_EXISTS;
+  using ::int64_t _LIBCPP_USING_IF_EXISTS;
+
+  using ::int_fast16_t;
+  using ::int_fast32_t;
+  using ::int_fast64_t;
+  using ::int_fast8_t;
+
+  using ::int_least16_t;
+  using ::int_least32_t;
+  using ::int_least64_t;
+  using ::int_least8_t;
+
+  using ::intmax_t;
+
+  using ::intptr_t _LIBCPP_USING_IF_EXISTS;
+
+  // unsigned
+  using ::uint8_t _LIBCPP_USING_IF_EXISTS;
+  using ::uint16_t _LIBCPP_USING_IF_EXISTS;
+  using ::uint32_t _LIBCPP_USING_IF_EXISTS;
+  using ::uint64_t _LIBCPP_USING_IF_EXISTS;
+
+  using ::uint_fast16_t;
+  using ::uint_fast32_t;
+  using ::uint_fast64_t;
+  using ::uint_fast8_t;
+
+  using ::uint_least16_t;
+  using ::uint_least32_t;
+  using ::uint_least64_t;
+  using ::uint_least8_t;
+
+  using ::uintmax_t;
+
+  using ::uintptr_t _LIBCPP_USING_IF_EXISTS;
+} // export
+
+// cstdio.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::FILE;
+  using ::fpos_t;
+  using ::size_t;
+
+  using ::clearerr;
+  using ::fclose;
+  using ::feof;
+  using ::ferror;
+  using ::fflush;
+  using ::fgetc;
+  using ::fgetpos;
+  using ::fgets;
+  using ::fopen;
+  using ::fprintf;
+  using ::fputc;
+  using ::fputs;
+  using ::fread;
+  using ::freopen;
+  using ::fscanf;
+  using ::fseek;
+  using ::fsetpos;
+  using ::ftell;
+  using ::fwrite;
+  using ::getc;
+  using ::getchar;
+  using ::perror;
+  using ::printf;
+  using ::putc;
+  using ::putchar;
+  using ::puts;
+  using ::remove;
+  using ::rename;
+  using ::rewind;
+  using ::scanf;
+  using ::setbuf;
+  using ::setvbuf;
+  using ::snprintf;
+  using ::sprintf;
+  using ::sscanf;
+  using ::tmpfile;
+  using ::tmpnam;
+  using ::ungetc;
+  using ::vfprintf;
+  using ::vfscanf;
+  using ::vprintf;
+  using ::vscanf;
+  using ::vsnprintf;
+  using ::vsprintf;
+  using ::vsscanf;
+
+} // export
+
+// cstdlib.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::div_t;
+  using ::ldiv_t;
+  using ::lldiv_t;
+  using ::size_t;
+
+  // [support.start.term], start and termination
+  using ::_Exit;
+  using ::abort;
+  using ::at_quick_exit _LIBCPP_USING_IF_EXISTS;
+  using ::atexit;
+  using ::exit;
+  using ::quick_exit _LIBCPP_USING_IF_EXISTS;
+
+  using ::getenv;
+  using ::system;
+
+  // [c.malloc], C library memory allocation
+  using ::aligned_alloc _LIBCPP_USING_IF_EXISTS;
+  using ::calloc;
+  using ::free;
+  using ::malloc;
+  using ::realloc;
+
+  using ::atof;
+  using ::atoi;
+  using ::atol;
+  using ::atoll;
+  using ::strtod;
+  using ::strtof;
+  using ::strtol;
+  using ::strtold;
+  using ::strtoll;
+  using ::strtoul;
+  using ::strtoull;
+
+  // [c.mb.wcs], multibyte / wide string and character conversion functions
+  using ::mblen;
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+  using ::mbstowcs;
+  using ::mbtowc;
+  using ::wcstombs;
+  using ::wctomb;
+#endif
+  // [alg.c.library], C standard library algorithms
+  using ::bsearch;
+  using ::qsort;
+
+  // [c.math.rand], low-quality random number generation
+  using ::rand;
+  using ::srand;
+
+  // [c.math.abs], absolute values
+  using ::abs;
+
+  using ::labs;
+  using ::llabs;
+
+  using ::div;
+  using ::ldiv;
+  using ::lldiv;
+
+} // export
+
+// cstring.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::size_t;
+
+  using ::memchr;
+  using ::memcmp;
+  using ::memcpy;
+  using ::memmove;
+  using ::memset;
+  using ::strcat;
+  using ::strchr;
+  using ::strcmp;
+  using ::strcoll;
+  using ::strcpy;
+  using ::strcspn;
+  using ::strerror;
+  using ::strlen;
+  using ::strncat;
+  using ::strncmp;
+  using ::strncpy;
+  using ::strpbrk;
+  using ::strrchr;
+  using ::strspn;
+  using ::strstr;
+  using ::strtok;
+  using ::strxfrm;
+
+} // export
+
+// ctime.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  using ::clock_t;
+  using ::size_t;
+  using ::time_t;
+
+  using ::timespec;
+  using ::tm;
+
+  using ::asctime;
+  using ::clock;
+  using ::ctime;
+  using ::difftime;
+  using ::gmtime;
+  using ::localtime;
+  using ::mktime;
+  using ::strftime;
+  using ::time;
+  using ::timespec_get _LIBCPP_USING_IF_EXISTS;
+} // export
+
+// cuchar.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+  // Note the Standard does not mark these symbols optional, but libc++'s header
+  // does. So this seems strictly not to be conforming.
+
+  // mbstate_t is conditionally here, but always present in cwchar.cppm. To avoid
+  // conflicing declarations omit the using here.
+
+  // size_t is conditionally here, but always present in cstddef.cppm. To avoid
+  // conflicing declarations omit the using here.
+
+#if !defined(_LIBCPP_HAS_NO_C8RTOMB_MBRTOC8)
+  using ::mbrtoc8 _LIBCPP_USING_IF_EXISTS;
+  using ::c8rtomb _LIBCPP_USING_IF_EXISTS;
+#endif
+  using ::mbrtoc16 _LIBCPP_USING_IF_EXISTS;
+  using ::c16rtomb _LIBCPP_USING_IF_EXISTS;
+  using ::mbrtoc32 _LIBCPP_USING_IF_EXISTS;
+  using ::c32rtomb _LIBCPP_USING_IF_EXISTS;
+} // export
+
+// cwchar.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+  using ::mbstate_t;
+  using ::size_t;
+  using ::wint_t;
+
+  using ::tm;
+
+  using ::btowc;
+  using ::fgetwc;
+  using ::fgetws;
+  using ::fputwc;
+  using ::fputws;
+  using ::fwide;
+  using ::fwprintf;
+  using ::fwscanf;
+  using ::getwc;
+  using ::getwchar;
+  using ::putwc;
+  using ::putwchar;
+  using ::swprintf;
+  using ::swscanf;
+  using ::ungetwc;
+  using ::vfwprintf;
+  using ::vfwscanf;
+  using ::vswprintf;
+  using ::vswscanf;
+  using ::vwprintf;
+  using ::vwscanf;
+  using ::wcscat;
+  using ::wcschr;
+  using ::wcscmp;
+  using ::wcscoll;
+  using ::wcscpy;
+  using ::wcscspn;
+  using ::wcsftime;
+  using ::wcslen;
+  using ::wcsncat;
+  using ::wcsncmp;
+  using ::wcsncpy;
+  using ::wcspbrk;
+  using ::wcsrchr;
+  using ::wcsspn;
+  using ::wcsstr;
+  using ::wcstod;
+  using ::wcstof;
+  using ::wcstok;
+  using ::wcstol;
+  using ::wcstold;
+  using ::wcstoll;
+  using ::wcstoul;
+  using ::wcstoull;
+  using ::wcsxfrm;
+  using ::wctob;
+  using ::wmemchr;
+  using ::wmemcmp;
+  using ::wmemcpy;
+  using ::wmemmove;
+  using ::wmemset;
+  using ::wprintf;
+  using ::wscanf;
+
+  // [c.mb.wcs], multibyte / wide string and character conversion functions
+  using ::mbrlen;
+  using ::mbrtowc;
+  using ::mbsinit;
+  using ::mbsrtowcs;
+  using ::wcrtomb;
+  using ::wcsrtombs;
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+} // export
+
+// cwctype.inc
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+export {
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+  using ::wctrans_t;
+  using ::wctype_t;
+  using ::wint_t;
+
+  using ::iswalnum;
+  using ::iswalpha;
+  using ::iswblank;
+  using ::iswcntrl;
+  using ::iswctype;
+  using ::iswdigit;
+  using ::iswgraph;
+  using ::iswlower;
+  using ::iswprint;
+  using ::iswpunct;
+  using ::iswspace;
+  using ::iswupper;
+  using ::iswxdigit;
+  using ::towctrans;
+  using ::towlower;
+  using ::towupper;
+  using ::wctrans;
+  using ::wctype;
+#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+} // export
diff --git a/libbuild2/cc/std.cppm b/libbuild2/cc/std.cppm
index 5368d1c..575e6a4 100644
--- a/libbuild2/cc/std.cppm
+++ b/libbuild2/cc/std.cppm
@@ -8,15 +8,15 @@
 //===----------------------------------------------------------------------===//
 
 // WARNING, this entire header is generated by
-// utils/generate_std_cppm_in.py
+// utils/generate_libcxx_cppm_in.py
 // DO NOT MODIFY!
 
 module;
 
 #include <__config>
 
-#if _LIBCPP_VERSION < 170000
-#error libc++ version 17.0.0 or later required
+#if _LIBCPP_VERSION < 180000
+#error libc++ version 18.0.0 or later required
 #endif
 
 // The headers of Table 24: C++ library headers [tab:headers.cpp]
@@ -153,11 +153,8 @@ module;
 #  include <strstream>
 #endif
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#if __has_include(<syncstream>)
-#  define _LIPCPP_HAS_YES_SYNCSTREAM
 #  include <syncstream>
 #endif
-#endif
 #include <system_error>
 #if !defined(_LIBCPP_HAS_NO_THREADS)
 #  include <thread>
@@ -177,38 +174,38 @@ module;
 #if 0
 // *** Headers not yet available ***
 #if __has_include(<debugging>)
-#  error "update the header information for <debugging> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<debugging>)
+#  error "please update the header information for <debugging> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<debugging>)
 #if __has_include(<flat_map>)
-#  error "update the header information for <flat_map> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<flat_map>)
+#  error "please update the header information for <flat_map> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<flat_map>)
 #if __has_include(<flat_set>)
-#  error "update the header information for <flat_set> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<flat_set>)
+#  error "please update the header information for <flat_set> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<flat_set>)
 #if __has_include(<generator>)
-#  error "update the header information for <generator> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<generator>)
+#  error "please update the header information for <generator> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<generator>)
 #if __has_include(<hazard_pointer>)
-#  error "update the header information for <hazard_pointer> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<hazard_pointer>)
+#  error "please update the header information for <hazard_pointer> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<hazard_pointer>)
 #if __has_include(<linalg>)
-#  error "update the header information for <linalg> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<linalg>)
+#  error "please update the header information for <linalg> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<linalg>)
 #if __has_include(<rcu>)
-#  error "update the header information for <rcu> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<rcu>)
+#  error "please update the header information for <rcu> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<rcu>)
 #if __has_include(<spanstream>)
-#  error "update the header information for <spanstream> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<spanstream>)
+#  error "please update the header information for <spanstream> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<spanstream>)
 #if __has_include(<stacktrace>)
-#  error "update the header information for <stacktrace> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<stacktrace>)
+#  error "please update the header information for <stacktrace> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<stacktrace>)
 #if __has_include(<stdfloat>)
-#  error "update the header information for <stdfloat> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<stdfloat>)
+#  error "please update the header information for <stdfloat> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<stdfloat>)
 #if __has_include(<text_encoding>)
-#  error "update the header information for <text_encoding> in libcxx/utils/generate_std_cppm_in.py"
-#endif //   __has_include(<text_encoding>)
+#  error "please update the header information for <text_encoding> in headers_not_available in utils/libcxx/header_information.py"
+#endif // __has_include(<text_encoding>)
 #endif
 
 export module std;
@@ -232,7 +229,9 @@ export namespace std {
     using std::ranges::in_in_result;
     using std::ranges::in_out_out_result;
     using std::ranges::in_out_result;
-    // using std::ranges::in_value_result;
+#if _LIBCPP_STD_VER >= 23
+    using std::ranges::in_value_result;
+#endif
     using std::ranges::min_max_result;
     // using std::ranges::out_value_result;
   } // namespace ranges
@@ -256,13 +255,15 @@ export namespace std {
     using std::ranges::none_of;
   }
 
+#if _LIBCPP_STD_VER >= 23
   // [alg.contains], contains
-#if 0
   namespace ranges {
     using std::ranges::contains;
+#if 0
     using std::ranges::contains_subrange;
-  } // namespace ranges
 #endif
+  } // namespace ranges
+#endif // _LIBCPP_STD_VER >= 23
 
   // [alg.foreach], for each
   using std::for_each;
@@ -370,20 +371,18 @@ export namespace std {
     // [alg.starts.with], starts with
     using std::ranges::starts_with;
 
-#if _LIBCPP_VERSION >= 180000
     // [alg.ends.with], ends with
     using std::ranges::ends_with;
-#endif
 
-#  if 0
     // [alg.fold], fold
     using std::ranges::fold_left;
+    using std::ranges::fold_left_with_iter;
+    using std::ranges::fold_left_with_iter_result;
+#  if 0
     using std::ranges::fold_left_first;
     using std::ranges::fold_right;
     using std::ranges::fold_right_last;
     using std::ranges::fold_left_with_iter;
-    using std::ranges::fold_left_with_iter_result;
-    using std::ranges::fold_left_with_iter;
     using std::ranges::fold_left_first_with_iter;
     using std::ranges::fold_left_first_with_iter;
 #  endif
@@ -955,7 +954,9 @@ export namespace std {
   using std::atomic_char;
   using std::atomic_char16_t;
   using std::atomic_char32_t;
+#ifndef _LIBCPP_HAS_NO_CHAR8_T
   using std::atomic_char8_t;
+#endif
   using std::atomic_int;
   using std::atomic_llong;
   using std::atomic_long;
@@ -1993,11 +1994,13 @@ export namespace std {
 
 export namespace std {
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
+#  if _LIBCPP_STD_VER < 26 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_CODECVT)
   using std::codecvt_mode;
 
   using std::codecvt_utf16;
   using std::codecvt_utf8;
   using std::codecvt_utf8_utf16;
+#  endif // _LIBCPP_STD_VER < 26 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_CODECVT)
 #endif // _LIBCPP_HAS_NO_LOCALIZATION
 } // namespace std
 
@@ -2617,7 +2620,7 @@ export namespace std {
   using std::mktime;
   using std::strftime;
   using std::time;
-  using std::timespec_get;
+  using std::timespec_get _LIBCPP_USING_IF_EXISTS;
 } // namespace std
 
 // cuchar.inc
@@ -3108,6 +3111,9 @@ export namespace std {
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
   using std::wformat_string;
 #endif
+#if _LIBCPP_STD_VER >= 26
+  using std::runtime_format;
+#endif //_LIBCPP_STD_VER >= 26
 
   // [format.functions], formatting functions
   using std::format;
@@ -3590,9 +3596,11 @@ export namespace std {
 #endif
   using std::u16streampos;
   using std::u32streampos;
+#ifndef _LIBCPP_HAS_NO_CHAR8_T
   using std::u8streampos;
+#endif
 
-#ifdef _LIBCPP_HAS_YES_SYNCSTREAM
+#ifndef _LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM
   using std::basic_osyncstream;
   using std::basic_syncbuf;
 #endif
@@ -3600,13 +3608,11 @@ export namespace std {
   using std::istreambuf_iterator;
   using std::ostreambuf_iterator;
 
-#ifdef _LIBCPP_HAS_YES_SYNCSTREAM
+#ifndef _LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM
   using std::osyncstream;
   using std::syncbuf;
-#endif
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-#ifdef _LIBCPP_HAS_YES_SYNCSTREAM
   using std::wosyncstream;
   using std::wsyncbuf;
 #endif
@@ -4112,9 +4118,7 @@ export namespace std {
   // [mdspan.layout], layout mapping
   using std::layout_left;
   using std::layout_right;
-#if _LIBCPP_VERSION >= 180000
   using std::layout_stride;
-#endif
 
   // [mdspan.accessor.default], class template default_accessor
   using std::default_accessor;
@@ -4171,7 +4175,9 @@ export namespace std {
 #if _LIBCPP_STD_VER >= 23
   using std::allocation_result;
 
-  using std::allocate_at_least;
+  // Note: no longer in Clang 19.
+  //
+  //using std::allocate_at_least;
 #endif
 
   // [default.allocator], the default allocator
@@ -4283,7 +4289,9 @@ export namespace std {
   using std::reinterpret_pointer_cast;
   using std::static_pointer_cast;
 
+#ifndef _LIBCPP_HAS_NO_RTTI
   using std::get_deleter;
+#endif // _LIBCPP_HAS_NO_RTTI
 
   // [util.smartptr.shared.io], shared_ptr I/O
 
@@ -4555,6 +4563,16 @@ export namespace std {
 
   // [numeric.ops.midpoint], midpoint
   using std::midpoint;
+
+#if _LIBCPP_STD_VER >= 26
+  // [numeric.sat], saturation arithmetic
+  using std::add_sat;
+  using std::div_sat;
+  using std::mul_sat;
+  using std::saturate_cast;
+  using std::sub_sat;
+#endif
+
 } // namespace std
 
 // optional.inc
@@ -4626,14 +4644,17 @@ export namespace std {
 #  endif
   using std::operator<<;
 
-#  if 0
+#  if _LIBCPP_STD_VER >= 23
   // [ostream.formatted.print], print functions
   using std::print;
   using std::println;
 
   using std::vprint_nonunicode;
+#    ifndef _LIBCPP_HAS_NO_UNICODE
   using std::vprint_unicode;
-#  endif
+#    endif // _LIBCPP_HAS_NO_UNICODE
+#  endif   // _LIBCPP_STD_VER >= 23
+
 #endif // _LIBCPP_HAS_NO_LOCALIZATION
 } // namespace std
 
@@ -5013,13 +5034,11 @@ export namespace std {
       using std::ranges::views::drop_while;
     } // namespace views
 
-#ifdef _LIBCPP_ENABLE_EXPERIMENTAL
     using std::ranges::join_view;
 
     namespace views {
       using std::ranges::views::join;
     } // namespace views
-#endif // _LIBCPP_ENABLE_EXPERIMENTAL
 #if 0
     using std::ranges::join_with_view;
 
@@ -5123,14 +5142,12 @@ export namespace std {
 #endif
 
 #if _LIBCPP_STD_VER >= 23
-#if _LIBCPP_VERSION >= 180000
     // [range.chunk.by], chunk by view
     using std::ranges::chunk_by_view;
 
     namespace views {
       using std::ranges::views::chunk_by;
     }
-#endif
 #endif // _LIBCPP_STD_VER >= 23
 
 #if 0
@@ -5783,7 +5800,9 @@ export namespace std {
   using std::string;
   using std::u16string;
   using std::u32string;
+#ifndef _LIBCPP_HAS_NO_CHAR8_T
   using std::u8string;
+#endif
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
   using std::wstring;
 #endif
@@ -5807,7 +5826,9 @@ export namespace std {
     using std::pmr::string;
     using std::pmr::u16string;
     using std::pmr::u32string;
+#ifndef _LIBCPP_HAS_NO_CHAR8_T
     using std::pmr::u8string;
+#endif
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
     using std::pmr::wstring;
 #endif
@@ -5816,17 +5837,12 @@ export namespace std {
   // [basic.string.hash], hash support
   using std::hash;
 
-  // TODO MODULES is this a bug?
-#if _LIBCPP_STD_VER >= 23
-  using std::operator""s;
-#else
   inline namespace literals {
     inline namespace string_literals {
       // [basic.string.literals], suffix for basic_string literals
       using std::literals::string_literals::operator""s;
     } // namespace string_literals
-  }   // namespace literals
-#endif
+  } // namespace literals
 } // namespace std
 
 // string_view.inc
@@ -5859,7 +5875,9 @@ export namespace std {
   using std::string_view;
   using std::u16string_view;
   using std::u32string_view;
+#ifndef _LIBCPP_HAS_NO_CHAR8_T
   using std::u8string_view;
+#endif
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
   using std::wstring_view;
 #endif
@@ -5904,8 +5922,6 @@ export namespace std {
 //
 //===----------------------------------------------------------------------===//
 
-#ifdef _LIBCPP_HAS_YES_SYNCSTREAM
-
 export namespace std {
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM)
   using std::basic_syncbuf;
@@ -5926,8 +5942,6 @@ export namespace std {
 #endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM)
 } // namespace std
 
-#endif
-
 // system_error.inc
 // -*- C++ -*-
 //===----------------------------------------------------------------------===//