[NFC] Simplify Forbidden Prefix API

Rephrase it in terms of DeclBaseName and fix up some callsites.

Author: CodaFi

lib/Sema/TypeCheckConstraints.cpp

@@ -1119,7 +1119,8 @@ namespace {
         return finish(walkToClosureExprPre(closure), expr);
 
       if (auto unresolved = dyn_cast<UnresolvedDeclRefExpr>(expr)) {
-        TC.checkForForbiddenPrefix(unresolved);
+        TypeChecker::checkForForbiddenPrefix(
+            TC.Context, unresolved->getName().getBaseName());
         return finish(true, TC.resolveDeclRefExpr(unresolved, DC));
       }
 

lib/Sema/TypeCheckDecl.cpp

@@ -2211,6 +2211,8 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
     if (auto VD = dyn_cast<ValueDecl>(decl)) {
       auto &Context = TC.Context;
+      TypeChecker::checkForForbiddenPrefix(Context, VD->getBaseName());
+      
       checkRedeclaration(Context, VD);
 
       // Force some requests, which can produce diagnostics.
@@ -3594,7 +3596,6 @@ bool TypeChecker::isAvailabilitySafeForConformance(
 }
 
 void TypeChecker::typeCheckDecl(Decl *D) {
-  checkForForbiddenPrefix(D);
   DeclChecker(*this).visit(D);
 }
 
@@ -4127,7 +4128,7 @@ void TypeChecker::validateDecl(ValueDecl *D) {
   PrettyStackTraceDecl StackTrace("validating", D);
   FrontendStatsTracer StatsTracer(Context.Stats, "validate-decl", D);
 
-  checkForForbiddenPrefix(D);
+  TypeChecker::checkForForbiddenPrefix(Context, D->getBaseName());
 
   if (Context.Stats)
     Context.Stats->getFrontendCounters().NumDeclsValidated++;

lib/Sema/TypeCheckPattern.cpp

@@ -1006,9 +1006,9 @@ bool TypeChecker::coercePatternToType(Pattern *&P, TypeResolution resolution,
     P->setType(type);
     var->setNamingPattern(NP);
 
-    // FIXME: Should probably just remove the forbidden prefix stuff, it no
-    // longer makes a lot of sense in a request-based world.
-    checkForForbiddenPrefix(var);
+    // FIXME: This call can be removed once pattern binding validation is
+    // sufficiently requestified.
+    TypeChecker::checkForForbiddenPrefix(Context, var->getBaseName());
 
     // If we are inferring a variable to have type AnyObject.Type,
     // "()", an uninhabited type, or optional thereof, emit a diagnostic.

lib/Sema/TypeChecker.cpp

@@ -729,38 +729,18 @@ TypeChecker &swift::createTypeChecker(ASTContext &Ctx) {
   return TypeChecker::createForContext(Ctx);
 }
 
-// checkForForbiddenPrefix is for testing purposes.
-
-void TypeChecker::checkForForbiddenPrefix(const Decl *D) {
-  if (!hasEnabledForbiddenTypecheckPrefix())
+void TypeChecker::checkForForbiddenPrefix(ASTContext &C, DeclBaseName Name) {
+  if (C.LangOpts.DebugForbidTypecheckPrefix.empty())
     return;
-  if (auto VD = dyn_cast<ValueDecl>(D)) {
-    if (!VD->getBaseName().isSpecial())
-      checkForForbiddenPrefix(VD->getBaseName().getIdentifier().str());
-  }
-}
 
-void TypeChecker::checkForForbiddenPrefix(const UnresolvedDeclRefExpr *E) {
-  if (!hasEnabledForbiddenTypecheckPrefix())
+  // Don't touch special names or empty names.
+  if (Name.isSpecial() || Name.empty())
     return;
-  if (!E->getName().isSpecial())
-    checkForForbiddenPrefix(E->getName().getBaseIdentifier());
-}
 
-void TypeChecker::checkForForbiddenPrefix(Identifier Ident) {
-  if (!hasEnabledForbiddenTypecheckPrefix())
-    return;
-  checkForForbiddenPrefix(Ident.empty() ? StringRef() : Ident.str());
-}
-
-void TypeChecker::checkForForbiddenPrefix(StringRef Name) {
-  if (!hasEnabledForbiddenTypecheckPrefix())
-    return;
-  if (Name.empty())
-    return;
-  if (Name.startswith(Context.LangOpts.DebugForbidTypecheckPrefix)) {
+  StringRef Str = Name.getIdentifier().str();
+  if (Str.startswith(C.LangOpts.DebugForbidTypecheckPrefix)) {
     std::string Msg = "forbidden typecheck occurred: ";
-    Msg += Name;
+    Msg += Str;
     llvm::report_fatal_error(Msg);
   }
 }

lib/Sema/TypeChecker.h

@@ -1883,16 +1883,9 @@ class TypeChecker final : public LazyResolver {
   /// @}
 
   /// If LangOptions::DebugForbidTypecheckPrefix is set and the given decl
-  /// has a name with that prefix, an llvm fatal_error is triggered.
+  /// name starts with that prefix, an llvm fatal_error is triggered.
   /// This is for testing purposes.
-  void checkForForbiddenPrefix(const Decl *D);
-  void checkForForbiddenPrefix(const UnresolvedDeclRefExpr *E);
-  void checkForForbiddenPrefix(Identifier Ident);
-  void checkForForbiddenPrefix(StringRef Name);
-
-  bool hasEnabledForbiddenTypecheckPrefix() const {
-    return !Context.LangOpts.DebugForbidTypecheckPrefix.empty();
-  }
+  static void checkForForbiddenPrefix(ASTContext &C, DeclBaseName Name);
 
   /// Check error handling in the given type-checked top-level code.
   void checkTopLevelErrorHandling(TopLevelCodeDecl *D);