Add -print-static-build-config to print a static build conformance

Introduce the ability to form a `StaticBuildConfiguration` from
language options. Add a frontend option `-print-static-build-config`
to then print that static build configuration as JSON in a manner that
can be decoded into a `StaticBuildConfiguration`.

Most of the change here is in sinking the bridged ASTContext queries
of language options into a new BridgedLangOptions. The printing of the
static build configuration only has a LangOptions (not an ASTContext),
so this refactoring is required for printing.

lib/FrontendTool/FrontendTool.cpp

@@ -23,6 +23,7 @@
 #include "swift/FrontendTool/FrontendTool.h"
 #include "Dependencies.h"
 #include "TBD.h"
+#include "swift/AST/ASTBridging.h"
 #include "swift/AST/ASTDumper.h"
 #include "swift/AST/ASTMangler.h"
 #include "swift/AST/AvailabilityScope.h"
@@ -38,6 +39,7 @@
 #include "swift/AST/NameLookup.h"
 #include "swift/AST/TBDGenRequests.h"
 #include "swift/Basic/Assertions.h"
+#include "swift/Basic/BasicBridging.h"
 #include "swift/Basic/Defer.h"
 #include "swift/Basic/Edit.h"
 #include "swift/Basic/FileSystem.h"
@@ -50,6 +52,7 @@
 #include "swift/Basic/TargetInfo.h"
 #include "swift/Basic/UUID.h"
 #include "swift/Basic/Version.h"
+#include "swift/Bridging/ASTGen.h"
 #include "swift/ConstExtract/ConstExtract.h"
 #include "swift/DependencyScan/ScanDependencies.h"
 #include "swift/Frontend/CachedDiagnostics.h"
@@ -2255,6 +2258,14 @@ public:
   };
 };
 
+#if SWIFT_BUILD_SWIFT_SYNTAX
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
+extern "C" BridgedStringRef
+swift_ASTGen_printStaticBuildConfiguration(BridgedLangOptions cLangOpts);
+#pragma clang diagnostic pop
+#endif
+
 int swift::performFrontend(ArrayRef<const char *> Args,
                            const char *Argv0, void *MainAddr,
                            FrontendObserver *observer) {
@@ -2385,6 +2396,16 @@ int swift::performFrontend(ArrayRef<const char *> Args,
     return finishDiagProcessing(0, /*verifierEnabled*/ false);
   }
 
+  if (Invocation.getFrontendOptions().PrintBuildConfig) {
+#if SWIFT_BUILD_SWIFT_SYNTAX
+    auto resultText =
+        swift_ASTGen_printStaticBuildConfiguration(Invocation.getLangOptions());
+    llvm::outs() << resultText.unbridged();
+    swift_ASTGen_freeBridgedString(resultText);
+#endif
+    return finishDiagProcessing(0, /*verifierEnabled*/ false);
+  }
+
   if (Invocation.getFrontendOptions().PrintSupportedFeatures) {
     swift::features::printSupportedFeatures(llvm::outs());
     return finishDiagProcessing(0, /*verifierEnabled*/ false);