[libc++][test] Adds backdeployment shorthands.

Some changes in libc++ affect the dylib. These changes are not present
on systems that use the system dylib. Currently that are the Apple
backdeployment targets. Figuring out which MacOS versions to target is
not trivial for non-Apple engineers. These shorthands make it easier to
select the proper feature make a test UNSUPPORTED or XFAIL.

During the design discussion with @ldionne we considered whether or not
to add preprocessor definitions to allow partial disabling of a test.
This would be useful when an existing feature is changed by modifying
the dylib. In the end we decided not to add this feature to avoid
additional complexity in the tests. Instead the test will be disabled
for that target.

Author: mordante

libcxx/utils/libcxx/test/features.py

@@ -527,43 +527,124 @@ def check_gdb(cfg):
 # be achieved by creating a `.verify.cpp` test that checks for the right errors, and
 # mark that test as requiring `stdlib=<vendor>-libc++ && target=<target>`.
 DEFAULT_FEATURES += [
+    # Backdeployment short-hands
+    Feature(
+        name="using-built-library-before-llvm-11",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.9|10.10|10.11|10.12|10.13|10.14|10.15|11.0)(.0)?}}",
+            cfg.available_features,
+        )
+    ),
+    Feature(
+        name="using-built-library-before-llvm-12",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "using-built-library-before-llvm-11 || (stdlib=apple-libc++ && target={{.+}}-apple-macosx12.{{(0|1|2)}}.0)",
+            cfg.available_features,
+        )
+    ),
+
+    Feature(
+        name="using-built-library-before-llvm-13",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "using-built-library-before-llvm-12 || (stdlib=apple-libc++ && target={{.+}}-apple-macosx{{((12.(3|4|5|6|7))|(13.(0|1|2|3)))}}.0)",
+            cfg.available_features,
+        )
+    ),
+
+    Feature(
+        name="using-built-library-before-llvm-14",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "using-built-library-before-llvm-13",
+            cfg.available_features,
+        )
+    ),
+
+    Feature(
+        name="using-built-library-before-llvm-15",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "using-built-library-before-llvm-14 || (stdlib=apple-libc++ && target={{.+}}-apple-macosx13.{{(4|5|6)}}.0)",
+            cfg.available_features,
+        )
+    ),
+
+    Feature(
+        name="using-built-library-before-llvm-16",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "using-built-library-before-llvm-15 || (stdlib=apple-libc++ && target={{.+}}-apple-macosx14.{{(0|1|2|3)}}.0)",
+            cfg.available_features,
+        )
+    ),
+
+    Feature(
+        name="using-built-library-before-llvm-17",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "using-built-library-before-llvm-16",
+            cfg.available_features,
+        )
+    ),
+
+    Feature(
+        name="using-built-library-before-llvm-18",
+        when=lambda cfg: BooleanExpression.evaluate(
+            # For now, no released version of macOS contains LLVM 18
+            # TODO(ldionne) Please provide the correct value.
+            "using-built-library-before-llvm-17 || stdlib=apple-libc++ && target={{.+}}-apple-macosx{{.+}}",
+            cfg.available_features,
+        )
+    ),
+
+    Feature(
+        name="using-built-library-before-llvm-19",
+        when=lambda cfg: BooleanExpression.evaluate(
+            # For now, no released version of macOS contains LLVM 19
+            # TODO(ldionne) Please provide the correct value.
+            "using-built-library-before-llvm-18 || stdlib=apple-libc++ && target={{.+}}-apple-macosx{{.+}}",
+            cfg.available_features,
+        )
+    ),
+
     # Tests that require std::to_chars(floating-point) in the built library
     Feature(
         name="availability-fp_to_chars-missing",
         when=lambda cfg: BooleanExpression.evaluate(
-            "stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}}",
+            #"stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}}",
+            "using-built-library-before-llvm-13",
             cfg.available_features,
         ),
     ),
     # Tests that require https://wg21.link/P0482 support in the built library
     Feature(
         name="availability-char8_t_support-missing",
         when=lambda cfg: BooleanExpression.evaluate(
-            "stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0)(.0)?}}",
+            #"stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0)(.0)?}}",
+            "using-built-library-before-llvm-11",
             cfg.available_features,
         ),
     ),
     # Tests that require __libcpp_verbose_abort support in the built library
     Feature(
         name="availability-verbose_abort-missing",
         when=lambda cfg: BooleanExpression.evaluate(
-            "stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}}",
+            #"stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}}",
+            "using-built-library-before-llvm-13",
             cfg.available_features,
         ),
     ),
     # Tests that require std::pmr support in the built library
     Feature(
         name="availability-pmr-missing",
         when=lambda cfg: BooleanExpression.evaluate(
-            "stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}}",
+            #"stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}}",
+            "using-built-library-before-llvm-13",
             cfg.available_features,
         ),
     ),
     # Tests that require std::filesystem support in the built library
     Feature(
         name="availability-filesystem-missing",
         when=lambda cfg: BooleanExpression.evaluate(
-            "stdlib=apple-libc++ && target={{.+}}-apple-macosx10.{{(13|14)(.0)?}}",
+            #"stdlib=apple-libc++ && target={{.+}}-apple-macosx10.{{(13|14)(.0)?}}",
+            "using-built-library-before-llvm-16",
             cfg.available_features,
         ),
     ),
@@ -579,8 +660,17 @@ def check_gdb(cfg):
     Feature(
         name="availability-tzdb-missing",
         when=lambda cfg: BooleanExpression.evaluate(
-            # TODO(ldionne) Please provide the correct value.
-            "(stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}})",
+            #"(stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}})",
+            "using-built-library-before-llvm-16",
+            cfg.available_features,
+        ),
+    ),
+    # Tests that require support for <print> and std::print in <ostream> in the built library.
+    Feature(
+        name="availability-print-missing",
+        when=lambda cfg: BooleanExpression.evaluate(
+            #"stdlib=apple-libc++ && target={{.+}}-apple-macosx{{(10.9|10.10|10.11|10.12|10.13|10.14|10.15|11.0|12.0|13.0)(.0)?}}",
+            "using-built-library-before-llvm-18",
             cfg.available_features,
         ),
     ),