[ast] Add a helper method for checking if a pattern contains a var decl and adopt it.

Author: gottesmm

include/swift/AST/Pattern.h

@@ -168,6 +168,13 @@ class alignas(8) Pattern {
   /// pattern.
   void forEachVariable(llvm::function_ref<void(VarDecl *)> f) const;
 
+  /// Returns true if \p vd is in the pattern.
+  bool containsVarDecl(const VarDecl *inputVD) const {
+    bool result = false;
+    forEachVariable([&](VarDecl *vd) { result |= inputVD == vd; });
+    return result;
+  }
+
   /// apply the specified function to all pattern nodes recursively in
   /// this pattern.  This is a pre-order traversal.
   void forEachNode(llvm::function_ref<void(Pattern *)> f);

lib/AST/Decl.cpp

@@ -1307,14 +1307,14 @@ unsigned PatternBindingDecl::getPatternEntryIndexForVarDecl(const VarDecl *VD) c
 
   auto List = getPatternList();
   if (List.size() == 1) {
-    assert(patternContainsVarDeclBinding(List[0].getPattern(), VD) &&
+    assert(List[0].getPattern()->containsVarDecl(VD) &&
            "Single entry PatternBindingDecl is set up wrong");
     return 0;
   }
 
   unsigned Result = 0;
   for (auto entry : List) {
-    if (patternContainsVarDeclBinding(entry.getPattern(), VD))
+    if (entry.getPattern()->containsVarDecl(VD))
       return Result;
     ++Result;
   }
@@ -4927,12 +4927,6 @@ SourceRange VarDecl::getTypeSourceRangeForDiagnostics() const {
   return SourceRange();
 }
 
-static bool isVarInPattern(const VarDecl *vd, Pattern *p) {
-  bool foundIt = false;
-  p->forEachVariable([&](VarDecl *foundFD) { foundIt |= foundFD == vd; });
-  return foundIt;
-}
-
 static Optional<std::pair<CaseStmt *, Pattern *>>
 findParentPatternCaseStmtAndPattern(const VarDecl *inputVD) {
   auto getMatchingPattern = [&](CaseStmt *cs) -> Pattern * {
@@ -4946,7 +4940,7 @@ findParentPatternCaseStmtAndPattern(const VarDecl *inputVD) {
 
     // Then check the rest of our case label items.
     for (auto &item : cs->getMutableCaseLabelItems()) {
-      if (isVarInPattern(inputVD, item.getPattern())) {
+      if (item.getPattern()->containsVarDecl(inputVD)) {
         return item.getPattern();
       }
     }
@@ -5039,15 +5033,15 @@ Pattern *VarDecl::getParentPattern() const {
       // In a case statement, search for the pattern that contains it.  This is
       // a bit silly, because you can't have something like "case x, y:" anyway.
       for (auto items : cs->getCaseLabelItems()) {
-        if (isVarInPattern(this, items.getPattern()))
+        if (items.getPattern()->containsVarDecl(this))
           return items.getPattern();
       }
     }
 
     if (auto *LCS = dyn_cast<LabeledConditionalStmt>(stmt)) {
       for (auto &elt : LCS->getCond())
         if (auto pat = elt.getPatternOrNull())
-          if (isVarInPattern(this, pat))
+          if (pat->containsVarDecl(this))
             return pat;
     }
 

lib/Sema/MiscDiagnostics.cpp

@@ -2418,14 +2418,10 @@ VarDeclUsageChecker::~VarDeclUsageChecker() {
       // Only diagnose VarDecls from the first CaseLabelItem in CaseStmts, as
       // the remaining items must match it anyway.
       auto CaseItems = CS->getCaseLabelItems();
-      if (!CaseItems.empty()) {
-        bool InFirstCaseLabelItem = false;
-        CaseItems.front().getPattern()->forEachVariable([&](VarDecl *D) {
-          InFirstCaseLabelItem |= var == D;
-        });
-        if (!InFirstCaseLabelItem)
-          continue;
-      }
+      assert(!CaseItems.empty() &&
+             "If we have any case stmt var decls, we should have a case item");
+      if (!CaseItems.front().getPattern()->containsVarDecl(var))
+        continue;
     }
 
     // If this is a 'let' value, any stores to it are actually initializations,