[Sema] Stop on-demand type checking for 'VarDecl' in 'TapExpr'

Author: rintaro

include/swift/AST/Decl.h

@@ -4894,7 +4894,7 @@ class VarDecl : public AbstractStorageDecl {
   };
 
 protected:
-  PointerUnion<PatternBindingDecl *, Stmt *, VarDecl *, Expr *> Parent;
+  PointerUnion<PatternBindingDecl *, Stmt *, VarDecl *> Parent;
 
   VarDecl(DeclKind kind, bool isStatic, Introducer introducer,
           bool isCaptureList, SourceLoc nameLoc, Identifier name,
@@ -5005,22 +5005,6 @@ class VarDecl : public AbstractStorageDecl {
     Parent = v;
   }
 
-  /// Returns the parent expression that owns this var decl.
-  ///
-  /// Concrete use cases:
-  ///   * 'TapExpr' for interpolated string literal expression
-  Expr *getParentExpr() const {
-    if (!Parent)
-      return nullptr;
-    return Parent.dyn_cast<Expr *>();
-  }
-
-  /// Set \p e to be the expression that owns this var decl.
-  void setParentExpr(Expr *e) {
-    assert(e);
-    Parent = e;
-  }
-
   NamedPattern *getNamingPattern() const;
   void setNamingPattern(NamedPattern *Pat);
 

include/swift/AST/Expr.h

@@ -950,9 +950,11 @@ class TapExpr : public Expr {
   BraceStmt * getBody() const { return Body; }
   void setBody(BraceStmt * b) { Body = b; }
 
-  SourceLoc getLoc() const { return getStartLoc(); }
+  SourceLoc getLoc() const { return SubExpr ? SubExpr->getLoc() : SourceLoc(); }
 
-  SourceLoc getStartLoc() const;
+  SourceLoc getStartLoc() const {
+    return SubExpr ? SubExpr->getStartLoc() : SourceLoc();
+  }
 
   SourceLoc getEndLoc() const;
 

lib/AST/Expr.cpp

@@ -2390,23 +2390,13 @@ TapExpr::TapExpr(Expr * SubExpr, BraceStmt *Body)
     assert(!Body->empty() &&
          Body->getFirstElement().isDecl(DeclKind::Var) &&
          "First element of Body should be a variable to init with the subExpr");
-    getVar()->setParentExpr(this);
   }
 }
 
 VarDecl * TapExpr::getVar() const {
   return dyn_cast<VarDecl>(Body->getFirstElement().dyn_cast<Decl *>());
 }
 
-SourceLoc TapExpr::getStartLoc() const {
-  // Include the body in the range, assuming the body follows the SubExpr.
-  if (auto *const se = getSubExpr())
-    return se->getStartLoc();
-  if (auto *const b = getBody())
-    return b->getStartLoc();
-  return SourceLoc();
-}
-
 SourceLoc TapExpr::getEndLoc() const {
   // Include the body in the range, assuming the body follows the SubExpr.
   // Also, be (perhaps overly) defensive about null pointers & invalid

lib/Sema/CSApply.cpp

@@ -7697,8 +7697,11 @@ namespace {
         return true;
 
       case SolutionApplicationToFunctionResult::Delay: {
-        auto closure = cast<ClosureExpr>(fn.getAbstractClosureExpr());
-        ClosuresToTypeCheck.push_back(closure);
+        if (!Rewriter.cs.Options
+                .contains(ConstraintSystemFlags::LeaveClosureBodyUnchecked)) {
+          auto closure = cast<ClosureExpr>(fn.getAbstractClosureExpr());
+          ClosuresToTypeCheck.push_back(closure);
+        }
         return false;
       }
       }
@@ -8275,26 +8278,24 @@ Optional<SolutionApplicationTarget> ConstraintSystem::applySolution(
   if (!resultTarget)
     return None;
 
-  if (!Options.contains(ConstraintSystemFlags::LeaveClosureBodyUnchecked)) {
-    bool hadError = false;
-
-    // Visit closures that have non-single expression bodies.
-    for (auto *closure : walker.getClosuresToTypeCheck())
-      hadError |= TypeChecker::typeCheckClosureBody(closure);
+  // Visit closures that have non-single expression bodies.
+  bool hadError = false;
 
-    // Tap expressions too; they should or should not be
-    // type-checked under the same conditions as closure bodies.
-    for (auto tuple : walker.getTapsToTypeCheck()) {
-      auto tap = std::get<0>(tuple);
-      auto tapDC = std::get<1>(tuple);
-      hadError |= TypeChecker::typeCheckTapBody(tap, tapDC);
-    }
+  for (auto *closure : walker.getClosuresToTypeCheck())
+    hadError |= TypeChecker::typeCheckClosureBody(closure);
 
-    // If any of them failed to type check, bail.
-    if (hadError)
-      return None;
+  // Tap expressions too; they should or should not be
+  // type-checked under the same conditions as closure bodies.
+  for (auto tuple : walker.getTapsToTypeCheck()) {
+    auto tap = std::get<0>(tuple);
+    auto tapDC = std::get<1>(tuple);
+    hadError |= TypeChecker::typeCheckTapBody(tap, tapDC);
   }
 
+  // If any of them failed to type check, bail.
+  if (hadError)
+    return None;
+
   rewriter.finalize();
 
   return resultTarget;

lib/Sema/TypeCheckDecl.cpp

@@ -2242,20 +2242,12 @@ InterfaceTypeRequest::evaluate(Evaluator &eval, ValueDecl *D) const {
 
   case DeclKind::Var: {
     auto *VD = cast<VarDecl>(D);
-    Type interfaceType;
-    if (auto *parentE = VD->getParentExpr()) {
-      // Type check the ASTNode that contains the parent 'TapExpr' if it
-      // hasn't.
-      if (!parentE->getType())
-        swift::typeCheckASTNodeAtLoc(VD->getDeclContext(), parentE->getLoc());
-      interfaceType = parentE->getType();
-    } else if (auto *namingPattern = VD->getNamingPattern()) {
-      interfaceType = namingPattern->getType();
-    }
-
-    if (!interfaceType)
+    auto *namingPattern = VD->getNamingPattern();
+    if (!namingPattern) {
       return ErrorType::get(Context);
+    }
 
+    Type interfaceType = namingPattern->getType();
     if (interfaceType->hasArchetype())
       interfaceType = interfaceType->mapTypeOutOfContext();
 

lib/Sema/TypeCheckStmt.cpp

@@ -1913,6 +1913,11 @@ bool TypeCheckASTNodeAtLocRequest::evaluate(Evaluator &evaluator,
       if (SM.isBeforeInBuffer(endLoc, Loc))
         return {false, E};
 
+      // Don't walk into 'TapExpr'. They should be type checked with parent
+      // 'InterpolatedStringLiteralExpr'.
+      if (isa<TapExpr>(E))
+        return {false, E};
+
       if (auto closure = dyn_cast<ClosureExpr>(E)) {
         // NOTE: When a client wants to type check a closure signature, it
         // requests with closure's 'getLoc()' location.