Merge pull request swiftlang#79618 from Azoy/another-bug-another-dollar

[AST] Directly store GTPD in TypeValueExpr

Author: Azoy

include/swift/AST/Expr.h

@@ -1434,39 +1434,39 @@ class TypeExpr : public Expr {
 };
 
 class TypeValueExpr : public Expr {
-  TypeLoc paramTypeLoc;
+  GenericTypeParamDecl *paramDecl;
+  DeclNameLoc loc;
+  Type paramType;
 
-public:
-  /// Create a \c TypeValueExpr from an underlying parameter \c TypeRepr.
-  TypeValueExpr(TypeRepr *paramRepr) :
-      Expr(ExprKind::TypeValue, /*implicit*/ false), paramTypeLoc(paramRepr) {}
+  /// Create a \c TypeValueExpr from a given generic value param decl.
+  TypeValueExpr(DeclNameLoc loc, GenericTypeParamDecl *paramDecl) :
+      Expr(ExprKind::TypeValue, /*implicit*/ false), paramDecl(paramDecl),
+      loc(loc), paramType(nullptr) {}
 
-  /// Create a \c TypeValueExpr for a given \c TypeDecl at the specified
-  /// location.
+public:
+  /// Create a \c TypeValueExpr for a given \c GenericTypeParamDecl.
   ///
-  /// The given location must be valid. If it is not, you must use
-  /// \c TypeExpr::createImplicitForDecl instead.
-  static TypeValueExpr *createForDecl(DeclNameLoc Loc, TypeDecl *D,
-                                      DeclContext *DC);
+  /// The given location must be valid.
+  static TypeValueExpr *createForDecl(DeclNameLoc Loc, GenericTypeParamDecl *D);
 
-  TypeRepr *getParamTypeRepr() const {
-    return paramTypeLoc.getTypeRepr();
+  GenericTypeParamDecl *getParamDecl() const {
+    return paramDecl;
   }
 
   /// Retrieves the corresponding parameter type of the value referenced by this
   /// expression.
-  ArchetypeType *getParamType() const {
-    return paramTypeLoc.getType()->castTo<ArchetypeType>();
+  Type getParamType() const {
+    return paramType;
   }
 
   /// Sets the corresponding parameter type of the value referenced by this
   /// expression.
   void setParamType(Type paramType) {
-    paramTypeLoc.setType(paramType);
+    this->paramType = paramType;
   }
 
   SourceRange getSourceRange() const {
-    return paramTypeLoc.getSourceRange();
+    return loc.getSourceRange();
   }
 
   static bool classof(const Expr *E) {

lib/AST/Expr.cpp

@@ -2399,13 +2399,11 @@ bool Expr::isSelfExprOf(const AbstractFunctionDecl *AFD, bool sameBase) const {
   return false;
 }
 
-TypeValueExpr *TypeValueExpr::createForDecl(DeclNameLoc Loc, TypeDecl *Decl,
-                                            DeclContext *DC) {
-  ASTContext &C = Decl->getASTContext();
-  assert(Loc.isValid());
-  auto *Repr = UnqualifiedIdentTypeRepr::create(C, Loc, Decl->createNameRef());
-  Repr->setValue(Decl, DC);
-  return new (C) TypeValueExpr(Repr);
+TypeValueExpr *TypeValueExpr::createForDecl(DeclNameLoc loc, 
+                                            GenericTypeParamDecl *paramDecl) {
+  auto &ctx = paramDecl->getASTContext();
+  ASSERT(loc.isValid());
+  return new (ctx) TypeValueExpr(loc, paramDecl);
 }
 
 OpenedArchetypeType *OpenExistentialExpr::getOpenedArchetype() const {

lib/Sema/CSApply.cpp

@@ -3219,7 +3219,7 @@ namespace {
 
     Expr *visitTypeValueExpr(TypeValueExpr *expr) {
       auto toType = simplifyType(cs.getType(expr));
-      assert(toType->isEqual(expr->getParamType()->getValueType()));
+      assert(toType->isEqual(expr->getParamDecl()->getValueType()));
       cs.setType(expr, toType);
       return expr;
     }

lib/Sema/CSGen.cpp

@@ -1681,18 +1681,10 @@ namespace {
     }
 
     Type visitTypeValueExpr(TypeValueExpr *E) {
-      auto locator = CS.getConstraintLocator(E);
-      auto type = resolveTypeReferenceInExpression(E->getParamTypeRepr(),
-                                              TypeResolverContext::InExpression,
-                                                  locator);
-
-      if (!type || type->hasError()) {
-        return Type();
-      }
-
-      auto archetype = type->castTo<ArchetypeType>();
-      E->setParamType(archetype);
-      return archetype->getValueType();
+      auto ty = E->getParamDecl()->getDeclaredInterfaceType();
+      auto paramType = CS.DC->mapTypeIntoContext(ty);
+      E->setParamType(paramType);
+      return E->getParamDecl()->getValueType();
     }
 
     Type visitDotSyntaxBaseIgnoredExpr(DotSyntaxBaseIgnoredExpr *expr) {

lib/Sema/PreCheckTarget.cpp

@@ -792,7 +792,8 @@ Expr *TypeChecker::resolveDeclRefExpr(UnresolvedDeclRefExpr *UDRE,
                    : D->getInterfaceType());
     } else {
       if (makeTypeValue) {
-        return TypeValueExpr::createForDecl(UDRE->getNameLoc(), D, LookupDC);
+        return TypeValueExpr::createForDecl(UDRE->getNameLoc(),
+                                            cast<GenericTypeParamDecl>(D));
       } else {
         return TypeExpr::createForDecl(UDRE->getNameLoc(), D, LookupDC);
       }

test/Sema/value_generics.swift

@@ -42,6 +42,12 @@ extension A where N: P {} // expected-error {{value generic type 'N' cannot conf
 
 extension A where N == Int {} // expected-error {{cannot constrain value parameter 'N' to be type 'Int'}}
 
+extension A where N == 123 {
+  func thing() -> Int {
+    N // OK (this used to crash the compiler in a concrete case 'where N == 123')
+  }
+}
+
 func b(with a: A<123>) {} // OK
 func c<let M: Int>(with a: A<M>) {} // OK
 func d<T>(with a: A<T>) {} // expected-error {{cannot pass type 'T' as a value for generic value 'N'}}