Merge pull request #33314 from DougGregor/bind-case-pattern-vars

[Statement checker] Always wire up case vars with bindSwitchCasePatternVars

Author: DougGregor

include/swift/AST/Stmt.h

@@ -814,13 +814,13 @@ class CaseLabelItem {
     Default,
   };
 
-  Pattern *CasePattern;
+  llvm::PointerIntPair<Pattern *, 1, bool> CasePatternAndResolved;
   SourceLoc WhereLoc;
   llvm::PointerIntPair<Expr *, 1, Kind> GuardExprAndKind;
 
   CaseLabelItem(Kind kind, Pattern *casePattern, SourceLoc whereLoc,
                 Expr *guardExpr)
-    : CasePattern(casePattern), WhereLoc(whereLoc),
+    : CasePatternAndResolved(casePattern, false), WhereLoc(whereLoc),
       GuardExprAndKind(guardExpr, kind) {}
 
 public:
@@ -848,9 +848,19 @@ class CaseLabelItem {
   SourceLoc getEndLoc() const;
   SourceRange getSourceRange() const;
 
-  Pattern *getPattern() { return CasePattern; }
-  const Pattern *getPattern() const { return CasePattern; }
-  void setPattern(Pattern *CasePattern) { this->CasePattern = CasePattern; }
+  Pattern *getPattern() {
+    return CasePatternAndResolved.getPointer();
+  }
+  const Pattern *getPattern() const {
+    return CasePatternAndResolved.getPointer();
+  }
+  bool isPatternResolved() const {
+    return CasePatternAndResolved.getInt();
+  }
+  void setPattern(Pattern *CasePattern, bool resolved) {
+    this->CasePatternAndResolved.setPointer(CasePattern);
+    this->CasePatternAndResolved.setInt(resolved);
+  }
 
   /// Return the guard expression if present, or null if the case label has
   /// no guard.

lib/AST/ASTWalker.cpp

@@ -1628,7 +1628,7 @@ Stmt *Traversal::visitSwitchStmt(SwitchStmt *S) {
 Stmt *Traversal::visitCaseStmt(CaseStmt *S) {
   for (auto &CLI : S->getMutableCaseLabelItems()) {
     if (auto *newPattern = doIt(CLI.getPattern()))
-      CLI.setPattern(newPattern);
+      CLI.setPattern(newPattern, /*resolved=*/CLI.isPatternResolved());
     else
       return nullptr;
     if (CLI.getGuardExpr()) {

lib/AST/Stmt.cpp

@@ -392,16 +392,16 @@ SourceLoc RepeatWhileStmt::getEndLoc() const { return Cond->getEndLoc(); }
 
 SourceRange CaseLabelItem::getSourceRange() const {
   if (auto *E = getGuardExpr())
-    return { CasePattern->getStartLoc(), E->getEndLoc() };
-  return CasePattern->getSourceRange();
+    return { getPattern()->getStartLoc(), E->getEndLoc() };
+  return getPattern()->getSourceRange();
 }
 SourceLoc CaseLabelItem::getStartLoc() const {
-  return CasePattern->getStartLoc();
+  return getPattern()->getStartLoc();
 }
 SourceLoc CaseLabelItem::getEndLoc() const {
   if (auto *E = getGuardExpr())
     return E->getEndLoc();
-  return CasePattern->getEndLoc();
+  return getPattern()->getEndLoc();
 }
 
 CaseStmt::CaseStmt(CaseParentKind parentKind, SourceLoc itemIntroducerLoc,

lib/Sema/CSApply.cpp

@@ -8262,7 +8262,7 @@ ExprWalker::rewriteTarget(SolutionApplicationTarget target) {
                                          target.getDeclContext());
     if (auto coercedPattern = TypeChecker::coercePatternToType(
             contextualPattern, patternType, patternOptions)) {
-      (*caseLabelItem)->setPattern(coercedPattern);
+      (*caseLabelItem)->setPattern(coercedPattern, /*resolved=*/true);
     } else {
       return None;
     }
@@ -8584,7 +8584,8 @@ SolutionApplicationTarget SolutionApplicationTarget::walk(ASTWalker &walker) {
   case Kind::caseLabelItem:
     if (auto newPattern =
             caseLabelItem.caseLabelItem->getPattern()->walk(walker)) {
-      caseLabelItem.caseLabelItem->setPattern(newPattern);
+      caseLabelItem.caseLabelItem->setPattern(
+          newPattern, caseLabelItem.caseLabelItem->isPatternResolved());
     }
     if (auto guardExpr = caseLabelItem.caseLabelItem->getGuardExpr()) {
       if (auto newGuardExpr = guardExpr->walk(walker))

lib/Sema/CSGen.cpp

@@ -2660,12 +2660,14 @@ namespace {
 
           // Okay, resolve the pattern.
           Pattern *pattern = LabelItem.getPattern();
-          pattern = TypeChecker::resolvePattern(pattern, CS.DC,
-                                         /*isStmtCondition*/false);
-          if (!pattern) return false;
+          if (!LabelItem.isPatternResolved()) {
+            pattern = TypeChecker::resolvePattern(pattern, CS.DC,
+                                           /*isStmtCondition*/false);
+            if (!pattern) return false;
 
-          // Save that aside while we explore the type.
-          LabelItem.setPattern(pattern);
+            // Save that aside while we explore the type.
+            LabelItem.setPattern(pattern, /*resolved=*/true);
+          }
 
           // Require the pattern to have a particular shape: a number
           // of is-patterns applied to an irrefutable pattern.
@@ -2704,7 +2706,7 @@ namespace {
           if (!pattern)
             return false;
 
-          LabelItem.setPattern(pattern);
+          LabelItem.setPattern(pattern, /*resolved=*/true);
           return LabelItem.isSyntacticallyExhaustive();
         }
 
@@ -4229,14 +4231,17 @@ bool ConstraintSystem::generateConstraints(
     CaseStmt *caseStmt, DeclContext *dc, Type subjectType,
     ConstraintLocator *locator) {
   // Pre-bind all of the pattern variables within the case.
-  bindSwitchCasePatternVars(caseStmt);
+  bindSwitchCasePatternVars(dc, caseStmt);
 
   for (auto &caseLabelItem : caseStmt->getMutableCaseLabelItems()) {
     // Resolve the pattern.
-    auto *pattern = TypeChecker::resolvePattern(
-        caseLabelItem.getPattern(), dc, /*isStmtCondition=*/false);
-    if (!pattern)
-      return true;
+    auto *pattern = caseLabelItem.getPattern();
+    if (!caseLabelItem.isPatternResolved()) {
+      pattern = TypeChecker::resolvePattern(
+          pattern, dc, /*isStmtCondition=*/false);
+      if (!pattern)
+        return true;
+    }
 
     // Generate constraints for the pattern, including one-way bindings for
     // any variables that show up in this pattern, because those variables