Merge pull request #84280 from hamishknight/csapply-cleanup

Reapply: [Sema] Remove some unreachable code from CSApply

Author: hamishknight

include/swift/AST/DiagnosticsSema.def

@@ -254,13 +254,6 @@ ERROR(cannot_apply_lvalue_binop_to_subelement,none,
 ERROR(cannot_apply_lvalue_binop_to_rvalue,none,
       "left side of mutating operator has immutable type %0", (Type))
 
-ERROR(cannot_subscript_base,none,
-      "cannot subscript a value of type %0",
-      (Type))
-
-ERROR(cannot_subscript_ambiguous_base,none,
-      "cannot subscript a value of incorrect or ambiguous type", ())
-
 ERROR(cannot_subscript_nil_literal,none,
       "cannot subscript a nil literal value", ())
 ERROR(conditional_cast_from_nil,none,

include/swift/AST/Expr.h

@@ -3348,24 +3348,9 @@ class ABISafeConversionExpr : public ImplicitConversionExpr {
   }
 };
 
-/// This is a conversion from an expression of UnresolvedType to an arbitrary
-/// other type, and from an arbitrary type to UnresolvedType.  This node does
-/// not appear in valid code, only in code involving diagnostics.
-class UnresolvedTypeConversionExpr : public ImplicitConversionExpr {
-public:
-  UnresolvedTypeConversionExpr(Expr *subExpr, Type type)
-  : ImplicitConversionExpr(ExprKind::UnresolvedTypeConversion, subExpr, type) {}
-
-  static bool classof(const Expr *E) {
-    return E->getKind() == ExprKind::UnresolvedTypeConversion;
-  }
-};
-
 /// FunctionConversionExpr - Convert a function to another function type,
 /// which might involve renaming the parameters or handling substitutions
 /// of subtypes (in the return) or supertypes (in the input).
-///
-/// FIXME: This should be a CapturingExpr.
 class FunctionConversionExpr : public ImplicitConversionExpr {
 public:
   FunctionConversionExpr(Expr *subExpr, Type type)

include/swift/AST/ExprNodes.def

@@ -161,7 +161,6 @@ ABSTRACT_EXPR(ImplicitConversion, Expr)
   EXPR(Load, ImplicitConversionExpr)
   EXPR(ABISafeConversion, ImplicitConversionExpr)
   EXPR(DestructureTuple, ImplicitConversionExpr)
-  EXPR(UnresolvedTypeConversion, ImplicitConversionExpr)
   EXPR(FunctionConversion, ImplicitConversionExpr)
   EXPR(CovariantFunctionConversion, ImplicitConversionExpr)
   EXPR(CovariantReturnConversion, ImplicitConversionExpr)

include/swift/Sema/ConstraintSystem.h

@@ -1764,7 +1764,7 @@ class Solution {
   /// Retrieve the overload choice associated with the given
   /// locator.
   SelectedOverload getOverloadChoice(ConstraintLocator *locator) const {
-    return *getOverloadChoiceIfAvailable(locator);
+    return getOverloadChoiceIfAvailable(locator).value();
   }
 
   /// Retrieve the overload choice for the callee associated with the given

lib/AST/ASTDumper.cpp

@@ -3817,12 +3817,6 @@ class PrintExpr : public ExprVisitor<PrintExpr, void, Label>,
 
     printFoot();
   }
-  void visitUnresolvedTypeConversionExpr(UnresolvedTypeConversionExpr *E,
-                                         Label label) {
-    printCommon(E, "unresolvedtype_conversion_expr", label);
-    printRec(E->getSubExpr(), Label::optional("sub_expr"));
-    printFoot();
-  }
   void visitFunctionConversionExpr(FunctionConversionExpr *E, Label label) {
     printCommon(E, "function_conversion_expr", label);
     printRec(E->getSubExpr(), Label::optional("sub_expr"));

lib/AST/ASTPrinter.cpp

@@ -5558,9 +5558,6 @@ void PrintAST::visitMakeTemporarilyEscapableExpr(MakeTemporarilyEscapableExpr *e
 void PrintAST::visitProtocolMetatypeToObjectExpr(ProtocolMetatypeToObjectExpr *expr) {
 }
 
-void PrintAST::visitUnresolvedTypeConversionExpr(UnresolvedTypeConversionExpr *expr) {
-}
-
 void PrintAST::visitConditionalBridgeFromObjCExpr(ConditionalBridgeFromObjCExpr *expr) {
 }
 

lib/AST/Expr.cpp

@@ -414,7 +414,6 @@ ConcreteDeclRef Expr::getReferencedDecl(bool stopAtParenExpr) const {
 
   PASS_THROUGH_REFERENCE(Load, getSubExpr);
   NO_REFERENCE(DestructureTuple);
-  NO_REFERENCE(UnresolvedTypeConversion);
   PASS_THROUGH_REFERENCE(ABISafeConversion, getSubExpr);
   PASS_THROUGH_REFERENCE(FunctionConversion, getSubExpr);
   PASS_THROUGH_REFERENCE(CovariantFunctionConversion, getSubExpr);
@@ -783,7 +782,6 @@ bool Expr::canAppendPostfixExpression(bool appendingPostfixOperator) const {
   case ExprKind::Load:
   case ExprKind::ABISafeConversion:
   case ExprKind::DestructureTuple:
-  case ExprKind::UnresolvedTypeConversion:
   case ExprKind::FunctionConversion:
   case ExprKind::CovariantFunctionConversion:
   case ExprKind::CovariantReturnConversion:
@@ -993,7 +991,6 @@ bool Expr::isValidParentOfTypeExpr(Expr *typeExpr) const {
   case ExprKind::Binary:
   case ExprKind::Load:
   case ExprKind::DestructureTuple:
-  case ExprKind::UnresolvedTypeConversion:
   case ExprKind::ABISafeConversion:
   case ExprKind::FunctionConversion:
   case ExprKind::CovariantFunctionConversion:

lib/SILGen/SILGenExpr.cpp

@@ -481,8 +481,6 @@ namespace {
     RValue visitConditionalBridgeFromObjCExpr(ConditionalBridgeFromObjCExpr *E,
                                               SGFContext C);
     RValue visitArchetypeToSuperExpr(ArchetypeToSuperExpr *E, SGFContext C);
-    RValue visitUnresolvedTypeConversionExpr(UnresolvedTypeConversionExpr *E,
-                                             SGFContext C);
     RValue visitABISafeConversionExpr(ABISafeConversionExpr *E, SGFContext C) {
       llvm_unreachable("cannot appear in rvalue");
     }
@@ -1035,12 +1033,6 @@ RValue RValueEmitter::visitSuperRefExpr(SuperRefExpr *E, SGFContext C) {
   return RValue(SGF, E, result);
 }
 
-RValue RValueEmitter::
-visitUnresolvedTypeConversionExpr(UnresolvedTypeConversionExpr *E,
-                                  SGFContext C) {
-  llvm_unreachable("invalid code made its way into SILGen");
-}
-
 RValue RValueEmitter::visitOtherConstructorDeclRefExpr(
                                 OtherConstructorDeclRefExpr *E, SGFContext C) {
   // This should always be a child of an ApplyExpr and so will be emitted by