[libc++] Add availability markup for LLVM 19 and LLVM 20 (#140072)

An LLVM 19-aligned libc++ was released with macOS 15.4 (and corresponding OSes),
and LLVM-20 aligned with macOS 26.0. This patch adds availability markup to
reflect that.

Author: ldionne

libcxx/include/__configuration/availability.h

@@ -118,14 +118,40 @@
 #  define _LIBCPP_INTRODUCED_IN_LLVM_21_ATTRIBUTE __attribute__((unavailable))
 
 // LLVM 20
-// TODO: Fill this in
-#  define _LIBCPP_INTRODUCED_IN_LLVM_20 0
-#  define _LIBCPP_INTRODUCED_IN_LLVM_20_ATTRIBUTE __attribute__((unavailable))
+//
+// Note that versions for most Apple OSes were bumped forward and aligned in that release.
+#  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 260000) ||       \
+      (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 260000) ||     \
+      (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 260000) ||             \
+      (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 260000) ||       \
+      (defined(__ENVIRONMENT_BRIDGE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_BRIDGE_OS_VERSION_MIN_REQUIRED__ < 100000)
+#    define _LIBCPP_INTRODUCED_IN_LLVM_20 0
+#  else
+#    define _LIBCPP_INTRODUCED_IN_LLVM_20 1
+#  endif
+#  define _LIBCPP_INTRODUCED_IN_LLVM_20_ATTRIBUTE                                                                 \
+    __attribute__((availability(macos, strict, introduced = 26.0)))                                               \
+    __attribute__((availability(ios, strict, introduced = 26.0)))                                                 \
+    __attribute__((availability(tvos, strict, introduced = 26.0)))                                                \
+    __attribute__((availability(watchos, strict, introduced = 26.0)))                                             \
+    __attribute__((availability(bridgeos, strict, introduced = 10.0)))
 
 // LLVM 19
-// TODO: Fill this in
-#  define _LIBCPP_INTRODUCED_IN_LLVM_19 0
-#  define _LIBCPP_INTRODUCED_IN_LLVM_19_ATTRIBUTE __attribute__((unavailable))
+#  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 150400) ||       \
+      (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 180400) ||     \
+      (defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ < 180400) ||             \
+      (defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ < 110400) ||       \
+      (defined(__ENVIRONMENT_BRIDGE_OS_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_BRIDGE_OS_VERSION_MIN_REQUIRED__ < 90400)
+#    define _LIBCPP_INTRODUCED_IN_LLVM_19 0
+#  else
+#    define _LIBCPP_INTRODUCED_IN_LLVM_19 1
+#  endif
+#  define _LIBCPP_INTRODUCED_IN_LLVM_19_ATTRIBUTE                                                                 \
+    __attribute__((availability(macos, strict, introduced = 15.4)))                                               \
+    __attribute__((availability(ios, strict, introduced = 18.4)))                                                 \
+    __attribute__((availability(tvos, strict, introduced = 18.4)))                                                \
+    __attribute__((availability(watchos, strict, introduced = 11.4)))                                             \
+    __attribute__((availability(bridgeos, strict, introduced = 9.4)))
 
 // LLVM 18
 #  if (defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 150000) ||       \

libcxx/test/libcxx/input.output/iostreams.base/ios.base/ios.base.cons/dtor.uninitialized.pass.cpp

@@ -10,8 +10,7 @@
 
 // The fix for issue 57964 requires an updated dylib due to explicit
 // instantiations. That means Apple backdeployment targets remain broken.
-// TODO: Remove && !darwin once availability markup for LLVM 19 on macOS has been added
-// XFAIL: using-built-library-before-llvm-19 && !darwin
+// XFAIL: using-built-library-before-llvm-19
 
 // <ios>
 

libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/setbuf.pass.cpp

@@ -12,8 +12,7 @@
 
 // This test requires the fix to https://llvm.org/PR60509 in the dylib,
 // which landed in 5afb937d8a30445642ccaf33866ee4cdd0713222.
-// TODO: Remove && !darwin once availability markup for LLVM 19 on macOS has been added
-// XFAIL: using-built-library-before-llvm-19 && !darwin
+// XFAIL: using-built-library-before-llvm-19
 
 #include <fstream>
 #include <cstddef>

libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/sync.pass.cpp

@@ -13,8 +13,7 @@
 // The fix for bug 51497 and bug 51499 require and updated dylib due to
 // explicit instantiations. That means Apple backdeployment targets remain
 // broken.
-// TODO: Remove && !darwin once availability markup for LLVM 19 on macOS has been added
-// XFAIL: using-built-library-before-llvm-19 && !darwin
+// XFAIL: using-built-library-before-llvm-19
 
 #include <istream>
 #include <cassert>

libcxx/test/std/localization/locale.categories/category.numeric/locale.num.get/facet.num.get.members/get_double.pass.cpp

@@ -8,8 +8,7 @@
 
 // The fix for LWG2381 (https://github.com/llvm/llvm-project/pull/77948) changed behavior of
 // FP parsing. This requires 3e15c97fa3812993bdc319827a5c6d867b765ae8 in the dylib.
-// TODO: Remove && !darwin once availability markup for LLVM 19 on macOS has been added
-// XFAIL: using-built-library-before-llvm-19 && !darwin
+// XFAIL: using-built-library-before-llvm-19
 
 // <locale>
 

libcxx/test/std/localization/locale.categories/category.numeric/locale.num.get/facet.num.get.members/get_float.pass.cpp

@@ -8,8 +8,7 @@
 
 // The fix for LWG2381 (https://github.com/llvm/llvm-project/pull/77948) changed behavior of
 // FP parsing. This requires 3e15c97fa3812993bdc319827a5c6d867b765ae8 in the dylib.
-// TODO: Remove && !darwin once availability markup for LLVM 19 on macOS has been added
-// XFAIL: using-built-library-before-llvm-19 && !darwin
+// XFAIL: using-built-library-before-llvm-19
 
 // <locale>
 

libcxx/test/std/localization/locale.categories/category.numeric/locale.num.get/facet.num.get.members/get_long_double.pass.cpp

@@ -8,8 +8,7 @@
 
 // The fix for LWG2381 (https://github.com/llvm/llvm-project/pull/77948) changed behavior of
 // FP parsing. This requires 3e15c97fa3812993bdc319827a5c6d867b765ae8 in the dylib.
-// TODO: Remove && !darwin once availability markup for LLVM 19 on macOS has been added
-// XFAIL: using-built-library-before-llvm-19 && !darwin
+// XFAIL: using-built-library-before-llvm-19
 
 // <locale>
 

libcxx/test/std/strings/basic.string/string.capacity/over_max_size.pass.cpp

@@ -8,11 +8,13 @@
 
 // UNSUPPORTED: no-exceptions
 
-// After changing the alignment of the allocated pointer from 16 to 8, the exception
-// thrown is no longer `bad_alloc` but instead length_error on systems using new
-// headers but a dylib that doesn't contain 04ce0ba.
+// This test fails when using a built library that does not contain
+// 15860446a8c3, which changed the return value of max_size(). Without
+// that change, the built library believes the max size to be one greater
+// than it really is, and we fail to throw `length_error` from `string::resize()`,
+// which is explicitly instantiated in the built library.
 //
-// XFAIL: using-built-library-before-llvm-19
+// XFAIL: using-built-library-before-llvm-21
 
 // <string>
 

libcxx/utils/libcxx/test/features.py

@@ -733,17 +733,45 @@ def check_gdb(cfg):
 # Helpers to define correspondances between LLVM versions and vendor system versions.
 # Those are used for backdeployment features below, do not use directly in tests.
 DEFAULT_FEATURES += [
+    Feature(
+        name="_target-has-llvm-22",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "TBD",
+            cfg.available_features,
+        ),
+    ),
+    Feature(
+        name="_target-has-llvm-21",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "TBD",
+            cfg.available_features,
+        ),
+    ),
+    Feature(
+        name="_target-has-llvm-20",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "_target-has-llvm-21 || target={{.+}}-apple-macosx{{26.[0-9](.\d+)?}}",
+            cfg.available_features,
+        ),
+    ),
+    Feature(
+        name="_target-has-llvm-19",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "_target-has-llvm-20 || target={{.+}}-apple-macosx{{15.[4-9](.\d+)?}}",
+            cfg.available_features,
+        ),
+    ),
     Feature(
         name="_target-has-llvm-18",
         when=lambda cfg: BooleanExpression.evaluate(
-            "target={{.+}}-apple-macosx{{15(.[0-9]+)?(.[0-9]+)?}}",
+            "_target-has-llvm-19 || target={{.+}}-apple-macosx{{15.[0-3](.\d+)?}}",
             cfg.available_features,
         ),
     ),
     Feature(
         name="_target-has-llvm-17",
         when=lambda cfg: BooleanExpression.evaluate(
-            "_target-has-llvm-18 || target={{.+}}-apple-macosx{{14.[4-9](.[0-9]+)?}} || target={{.+}}-apple-macosx{{1[5-9]([.].+)?}}",
+            "_target-has-llvm-18 || target={{.+}}-apple-macosx{{14.[4-9](.\d+)?}}",
             cfg.available_features,
         ),
     ),
@@ -821,7 +849,7 @@ def check_gdb(cfg):
 # a libc++ flavor that enables availability markup. Similarly, a test could fail when
 # run against the system library of an older version of FreeBSD, even though FreeBSD
 # doesn't provide availability markup at the time of writing this.
-for version in ("12", "13", "14", "15", "16", "17", "18", "19", "20"):
+for version in ("12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22"):
     DEFAULT_FEATURES.append(
         Feature(
             name="using-built-library-before-llvm-{}".format(version),

libcxxabi/test/test_demangle.pass.cpp

@@ -13,6 +13,10 @@
 // dd8b266ef.
 // UNSUPPORTED: using-built-library-before-llvm-20
 
+// This test exercises support for BitInt demangling introduced in
+// 20f56d140909a01c74e9981835373eaab6021af9.
+// UNSUPPORTED: using-built-library-before-llvm-21
+
 // XFAIL: win32-broken-printf-a-precision
 
 #include "support/timer.h"