Merge pull request #38742 from beccadax/warring-triad

Start testing Swift 6 mode changes

Author: DougGregor

lib/Basic/Version.cpp

@@ -326,6 +326,17 @@ Optional<Version> Version::getEffectiveLanguageVersion() const {
     static_assert(SWIFT_VERSION_MAJOR == 5,
                   "getCurrentLanguageVersion is no longer correct here");
     return Version::getCurrentLanguageVersion();
+  case 6:
+    // Allow version '6' in asserts compilers *only* so that we can start
+    // testing changes slated for Swift 6. Note that it's still not listed in
+    // `Version::getValidEffectiveVersions()`.
+    // FIXME: When Swift 6 becomes real, remove 'REQUIRES: asserts' from tests
+    //        using '-swift-version 6'.
+#ifdef NDEBUG
+    LLVM_FALLTHROUGH;
+#else
+    return Version{6};
+#endif
   default:
     return None;
   }

lib/Frontend/CompilerInvocation.cpp

@@ -657,7 +657,8 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   }
 
   Opts.EnableConcisePoundFile =
-      Args.hasArg(OPT_enable_experimental_concise_pound_file);
+      Args.hasArg(OPT_enable_experimental_concise_pound_file) ||
+      Opts.EffectiveLanguageVersion.isVersionAtLeast(6);
   Opts.EnableFuzzyForwardScanTrailingClosureMatching =
       Args.hasFlag(OPT_enable_fuzzy_forward_scan_trailing_closure_matching,
                    OPT_disable_fuzzy_forward_scan_trailing_closure_matching,