Avoid depending on missing nodeToString and genericParameterName symbols in the freestanding stdlib (#42174) (#42215)

(cherry picked from commit 4511c47)

Author: kubamracek

lib/Demangling/Context.cpp

@@ -53,6 +53,8 @@ NodePointer Context::demangleTypeAsNode(llvm::StringRef MangledName) {
   return D->demangleType(MangledName);
 }
 
+#if SWIFT_STDLIB_HAS_TYPE_PRINTING
+
 std::string Context::demangleSymbolAsString(llvm::StringRef MangledName,
                                             const DemangleOptions &Options) {
   NodePointer root = demangleSymbolAsNode(MangledName);
@@ -75,6 +77,8 @@ std::string Context::demangleTypeAsString(llvm::StringRef MangledName,
   return demangling;
 }
 
+#endif
+
 // Removes a '.<n>' suffix from \p Name. <n> is either a number or a combination of
 // '.<other-text>.<n>'.
 // Such symbols are produced in IRGen or in LLVM optimizations.
@@ -243,6 +247,8 @@ std::string Context::getModuleName(llvm::StringRef mangledName) {
 // Public utility functions     //
 //////////////////////////////////
 
+#if SWIFT_STDLIB_HAS_TYPE_PRINTING
+
 std::string demangleSymbolAsString(const char *MangledName,
                                    size_t MangledNameLength,
                                    const DemangleOptions &Options) {
@@ -259,6 +265,8 @@ std::string demangleTypeAsString(const char *MangledName,
                                   Options);
 }
 
+#endif
+
 SWIFT_END_INLINE_NAMESPACE
 } // namespace Demangle
 } // namespace swift

stdlib/public/runtime/Demangle.cpp

@@ -720,6 +720,9 @@ char *swift_demangle(const char *mangledName,
   if (!Demangle::isSwiftSymbol(mangledName))
     return nullptr; // Not a mangled name
 
+#if !SWIFT_STDLIB_HAS_TYPE_PRINTING
+  return nullptr;
+#else
   // Demangle the name.
   auto options = Demangle::DemangleOptions();
   options.DisplayDebuggerGeneratedModule = false;
@@ -743,4 +746,5 @@ char *swift_demangle(const char *mangledName,
   }
 
   return outputBuffer;
+#endif
 }