Add a test feature 'swift_ast_verifier'

Author: gribozavr

docs/Testing.rst

@@ -308,7 +308,9 @@ use this pattern::
 Features for ``REQUIRES`` and ``XFAIL``
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-FIXME: list.
+FIXME: full list.
+
+* ``swift_ast_verifier``: present if the AST verifier is enabled in this build.
 
 When writing a test specific to x86, if possible, prefer ``REQUIRES:
 CPU=i386_or_x86_64`` to ``REQUIRES: CPU=x86_64``.

test/CMakeLists.txt

@@ -133,6 +133,7 @@ if(PYTHONINTERP_FOUND)
         # Normalize spelling of boolean values.
         normalize_boolean_spelling(LLVM_ENABLE_ASSERTIONS)
         normalize_boolean_spelling(SWIFT_STDLIB_ASSERTIONS)
+        normalize_boolean_spelling(SWIFT_AST_VERIFIER)
         normalize_boolean_spelling(SWIFT_ASAN_BUILD)
 
         # A directory where to put the xUnit-style XML test results.

test/lit.site.cfg.in

@@ -32,6 +32,9 @@ if "@SWIFT_STDLIB_ASSERTIONS@" == "TRUE":
 else:
     config.available_features.add('swift_stdlib_no_asserts')
 
+if "@SWIFT_AST_VERIFIER@" == "TRUE":
+    config.available_features.add('swift_ast_verifier')
+
 if "@SWIFT_OPTIMIZED@" == "TRUE":
     config.available_features.add("optimized_stdlib")
 

validation-test/compiler_crashers/26725-llvm-smallvectorimpl-swift-diagnosticargument-operator.swift

@@ -1,4 +1,8 @@
 // RUN: not --crash %target-swift-frontend %s -parse
+
+// This test fails in the AST verifier, which can be turned off.
+// REQUIRES: swift_ast_verifier
+
 // Distributed under the terms of the MIT license
 // Test case submitted to project by https://github.com/practicalswift (practicalswift)
 // Test case found by fuzzing