[AST] Make case body variables for CaseStmt non-optional

hamishknight · hamishknight · commit 84befd43abe6 · 2025-09-09T13:48:40.000+01:00
We don't really care about the distinction between empty and nil here.
diff --git a/include/swift/AST/Stmt.h b/include/swift/AST/Stmt.h
@@ -1222,13 +1222,12 @@ class CaseStmt final
 
   llvm::PointerIntPair<BraceStmt *, 1, bool> BodyAndHasFallthrough;
 
-  std::optional<ArrayRef<VarDecl *>> CaseBodyVariables;
+  ArrayRef<VarDecl *> CaseBodyVariables;
 
   CaseStmt(CaseParentKind ParentKind, SourceLoc ItemIntroducerLoc,
            ArrayRef<CaseLabelItem> CaseLabelItems, SourceLoc UnknownAttrLoc,
            SourceLoc ItemTerminatorLoc, BraceStmt *Body,
-           std::optional<ArrayRef<VarDecl *>> CaseBodyVariables,
-           std::optional<bool> Implicit,
+           ArrayRef<VarDecl *> CaseBodyVariables, std::optional<bool> Implicit,
            NullablePtr<FallthroughStmt> fallthroughStmt);
 
 public:
@@ -1248,7 +1247,7 @@ class CaseStmt final
   create(ASTContext &C, CaseParentKind ParentKind, SourceLoc ItemIntroducerLoc,
          ArrayRef<CaseLabelItem> CaseLabelItems, SourceLoc UnknownAttrLoc,
          SourceLoc ItemTerminatorLoc, BraceStmt *Body,
-         std::optional<ArrayRef<VarDecl *>> CaseBodyVariables,
+         ArrayRef<VarDecl *> CaseBodyVariables,
          std::optional<bool> Implicit = std::nullopt,
          NullablePtr<FallthroughStmt> fallthroughStmt = nullptr);
 
@@ -1293,7 +1292,7 @@ class CaseStmt final
   void setBody(BraceStmt *body) { BodyAndHasFallthrough.setPointer(body); }
 
   /// True if the case block declares any patterns with local variable bindings.
-  bool hasBoundDecls() const { return CaseBodyVariables.has_value(); }
+  bool hasCaseBodyVariables() const { return !CaseBodyVariables.empty(); }
 
   /// Get the source location of the 'case', 'default', or 'catch' of the first
   /// label.
@@ -1345,20 +1344,8 @@ class CaseStmt final
   }
 
   /// Return an ArrayRef containing the case body variables of this CaseStmt.
-  ///
-  /// Asserts if case body variables was not explicitly initialized. In contexts
-  /// where one wants a non-asserting version, \see
-  /// getCaseBodyVariablesOrEmptyArray.
   ArrayRef<VarDecl *> getCaseBodyVariables() const {
-    return *CaseBodyVariables;
-  }
-
-  bool hasCaseBodyVariables() const { return CaseBodyVariables.has_value(); }
-
-  ArrayRef<VarDecl *> getCaseBodyVariablesOrEmptyArray() const {
-    if (!CaseBodyVariables)
-      return ArrayRef<VarDecl *>();
-    return *CaseBodyVariables;
+    return CaseBodyVariables;
   }
 
   /// Find the next case statement within the same 'switch' or 'do-catch',
diff --git a/lib/AST/ASTScopeLookup.cpp b/lib/AST/ASTScopeLookup.cpp
@@ -378,10 +378,10 @@ bool CaseLabelItemScope::lookupLocalsOrMembers(DeclConsumer consumer) const {
 }
 
 bool CaseStmtBodyScope::lookupLocalsOrMembers(DeclConsumer consumer) const {
-  for (auto *var : stmt->getCaseBodyVariablesOrEmptyArray())
+  for (auto *var : stmt->getCaseBodyVariables()) {
     if (consumer.consume({var}))
-        return true;
-
+      return true;
+  }
   return false;
 }
 
diff --git a/lib/AST/ASTVerifier.cpp b/lib/AST/ASTVerifier.cpp
@@ -2795,7 +2795,7 @@ class Verifier : public ASTWalker {
         // guarantee that all case label items bind corresponding patterns and
         // the case body var decls of a case stmt are created from the var decls
         // of the first case label items.
-        if (!caseStmt->hasBoundDecls()) {
+        if (!caseStmt->hasCaseBodyVariables()) {
           Out << "parent CaseStmt of VarDecl does not have any case body "
                  "decls?!\n";
           abort();
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
@@ -8164,7 +8164,7 @@ findParentPatternCaseStmtAndPattern(const VarDecl *inputVD) {
   auto getMatchingPattern = [&](CaseStmt *cs) -> Pattern * {
     // Check if inputVD is in our case body var decls if we have any. If we do,
     // treat its pattern as our first case label item pattern.
-    for (auto *vd : cs->getCaseBodyVariablesOrEmptyArray()) {
+    for (auto *vd : cs->getCaseBodyVariables()) {
       if (vd == inputVD) {
         return cs->getMutableCaseLabelItems().front().getPattern();
       }
@@ -8345,7 +8345,7 @@ bool VarDecl::isCaseBodyVariable() const {
   auto *caseStmt = dyn_cast_or_null<CaseStmt>(getRecursiveParentPatternStmt());
   if (!caseStmt)
     return false;
-  return llvm::any_of(caseStmt->getCaseBodyVariablesOrEmptyArray(),
+  return llvm::any_of(caseStmt->getCaseBodyVariables(),
                       [&](VarDecl *vd) { return vd == this; });
 }
 
diff --git a/lib/AST/Stmt.cpp b/lib/AST/Stmt.cpp
@@ -752,8 +752,7 @@ SourceLoc CaseLabelItem::getEndLoc() const {
 CaseStmt::CaseStmt(CaseParentKind parentKind, SourceLoc itemIntroducerLoc,
                    ArrayRef<CaseLabelItem> caseLabelItems,
                    SourceLoc unknownAttrLoc, SourceLoc itemTerminatorLoc,
-                   BraceStmt *body,
-                   std::optional<ArrayRef<VarDecl *>> caseBodyVariables,
+                   BraceStmt *body, ArrayRef<VarDecl *> caseBodyVariables,
                    std::optional<bool> implicit,
                    NullablePtr<FallthroughStmt> fallthroughStmt)
     : Stmt(StmtKind::Case, getDefaultImplicitFlag(implicit, itemIntroducerLoc)),
@@ -781,7 +780,7 @@ CaseStmt::CaseStmt(CaseParentKind parentKind, SourceLoc itemIntroducerLoc,
     new (&items[i]) CaseLabelItem(caseLabelItems[i]);
     items[i].getPattern()->markOwnedByStatement(this);
   }
-  for (auto *vd : getCaseBodyVariablesOrEmptyArray()) {
+  for (auto *vd : getCaseBodyVariables()) {
     vd->setParentPatternStmt(this);
   }
 }
@@ -871,8 +870,7 @@ CaseStmt *
 CaseStmt::create(ASTContext &ctx, CaseParentKind ParentKind, SourceLoc caseLoc,
                  ArrayRef<CaseLabelItem> caseLabelItems,
                  SourceLoc unknownAttrLoc, SourceLoc colonLoc, BraceStmt *body,
-                 std::optional<ArrayRef<VarDecl *>> caseVarDecls,
-                 std::optional<bool> implicit,
+                 ArrayRef<VarDecl *> caseVarDecls, std::optional<bool> implicit,
                  NullablePtr<FallthroughStmt> fallthroughStmt) {
   void *mem =
       ctx.Allocate(totalSizeToAlloc<FallthroughStmt *, CaseLabelItem>(
diff --git a/lib/SILGen/SILGenPattern.cpp b/lib/SILGen/SILGenPattern.cpp
@@ -2836,7 +2836,7 @@ void PatternMatchEmission::initSharedCaseBlockDest(CaseStmt *caseBlock,
   result.first->second.first = block;
 
   // Add args for any pattern variables if we have any.
-  for (auto *vd : caseBlock->getCaseBodyVariablesOrEmptyArray()) {
+  for (auto *vd : caseBlock->getCaseBodyVariables()) {
     if (!vd->hasName())
       continue;
 
@@ -2867,7 +2867,7 @@ void PatternMatchEmission::emitAddressOnlyAllocations() {
     // If we have a shared case with bound decls, setup the arguments for the
     // shared block by emitting the temporary allocation used for the arguments
     // of the shared block.
-    for (auto *vd : caseBlock->getCaseBodyVariablesOrEmptyArray()) {
+    for (auto *vd : caseBlock->getCaseBodyVariables()) {
       if (!vd->hasName())
         continue;
 
diff --git a/lib/Sema/BuilderTransform.cpp b/lib/Sema/BuilderTransform.cpp
@@ -650,7 +650,7 @@ class ResultBuilderTransform
         caseStmt->getCaseLabelItems(),
         caseStmt->hasUnknownAttr() ? caseStmt->getStartLoc() : SourceLoc(),
         caseStmt->getItemTerminatorLoc(), cloneBraceWith(body, newBody),
-        caseStmt->getCaseBodyVariablesOrEmptyArray(), caseStmt->isImplicit(),
+        caseStmt->getCaseBodyVariables(), caseStmt->isImplicit(),
         caseStmt->getFallthroughStmt());
 
     return std::make_pair(caseVarRef.get(), newCase);
diff --git a/lib/Sema/CSSyntacticElement.cpp b/lib/Sema/CSSyntacticElement.cpp
@@ -1378,7 +1378,7 @@ class SyntacticElementConstraintGenerator
       pattern->forEachVariable([&](VarDecl *var) { recordVar(var); });
     }
 
-    for (auto bodyVar : caseStmt->getCaseBodyVariablesOrEmptyArray()) {
+    for (auto bodyVar : caseStmt->getCaseBodyVariables()) {
       if (!bodyVar->hasName())
         continue;
 
@@ -2007,7 +2007,7 @@ class SyntacticElementSolutionApplication
 
     bindSwitchCasePatternVars(context.getAsDeclContext(), caseStmt);
 
-    for (auto *expected : caseStmt->getCaseBodyVariablesOrEmptyArray()) {
+    for (auto *expected : caseStmt->getCaseBodyVariables()) {
       assert(expected->hasName());
       auto prev = expected->getParentVarDecl();
       auto type = solution.getResolvedType(prev)->mapTypeOutOfContext();
diff --git a/lib/Sema/DerivedConformance/DerivedConformanceCodable.cpp b/lib/Sema/DerivedConformance/DerivedConformanceCodable.cpp
@@ -946,7 +946,7 @@ createEnumSwitch(ASTContext &C, DeclContext *DC, Expr *expr, EnumDecl *enumDecl,
     // .<elt>(let a0, let a1, ...)
     SmallVector<VarDecl *, 3> payloadVars;
     Pattern *subpattern = nullptr;
-    std::optional<MutableArrayRef<VarDecl *>> caseBodyVarDecls;
+    ArrayRef<VarDecl *> caseBodyVarDecls;
 
     if (createSubpattern) {
       subpattern = DerivedConformance::enumElementPayloadSubpattern(
@@ -965,7 +965,7 @@ createEnumSwitch(ASTContext &C, DeclContext *DC, Expr *expr, EnumDecl *enumDecl,
           vNew->setImplicit();
           copy[i] = vNew;
         }
-        caseBodyVarDecls.emplace(copy);
+        caseBodyVarDecls = copy;
       }
     }
 
@@ -988,8 +988,7 @@ createEnumSwitch(ASTContext &C, DeclContext *DC, Expr *expr, EnumDecl *enumDecl,
       auto stmt =
           CaseStmt::create(C, CaseParentKind::Switch, SourceLoc(), labelItem,
                            SourceLoc(), SourceLoc(), caseBody,
-                           /*case body vardecls*/
-                           createSubpattern ? caseBodyVarDecls : std::nullopt);
+                           caseBodyVarDecls);
       cases.push_back(stmt);
     }
   }
diff --git a/lib/Sema/DerivedConformance/DerivedConformanceComparable.cpp b/lib/Sema/DerivedConformance/DerivedConformanceComparable.cpp
@@ -128,7 +128,7 @@ deriveBodyComparable_enum_hasAssociatedValues_lt(AbstractFunctionDecl *ltDecl, v
         enumType, elt, rhsSubpattern, /*DC*/ ltDecl);
 
     auto hasBoundDecls = !lhsPayloadVars.empty();
-    std::optional<MutableArrayRef<VarDecl *>> caseBodyVarDecls;
+    ArrayRef<VarDecl *> caseBodyVarDecls;
     if (hasBoundDecls) {
       // We allocated a direct copy of our lhs var decls for the case
       // body.
@@ -141,7 +141,7 @@ deriveBodyComparable_enum_hasAssociatedValues_lt(AbstractFunctionDecl *ltDecl, v
         vNew->setImplicit();
         copy[i] = vNew;
       }
-      caseBodyVarDecls.emplace(copy);
+      caseBodyVarDecls = copy;
     }
 
     // case (.<elt>(let l0, let l1, ...), .<elt>(let r0, let r1, ...))
diff --git a/lib/Sema/DerivedConformance/DerivedConformanceEquatableHashable.cpp b/lib/Sema/DerivedConformance/DerivedConformanceEquatableHashable.cpp
@@ -194,7 +194,7 @@ deriveBodyEquatable_enum_hasAssociatedValues_eq(AbstractFunctionDecl *eqDecl,
         enumType, elt, rhsSubpattern, /*DC*/ eqDecl);
 
     auto hasBoundDecls = !lhsPayloadVars.empty();
-    std::optional<MutableArrayRef<VarDecl *>> caseBodyVarDecls;
+    ArrayRef<VarDecl *> caseBodyVarDecls;
     if (hasBoundDecls) {
       // We allocated a direct copy of our lhs var decls for the case
       // body.
@@ -207,7 +207,7 @@ deriveBodyEquatable_enum_hasAssociatedValues_eq(AbstractFunctionDecl *eqDecl,
         vNew->setImplicit();
         copy[i] = vNew;
       }
-      caseBodyVarDecls.emplace(copy);
+      caseBodyVarDecls = copy;
     }
 
     // case (.<elt>(let l0, let l1, ...), .<elt>(let r0, let r1, ...))
@@ -736,7 +736,7 @@ deriveBodyHashable_enum_hasAssociatedValues_hashInto(
     }
 
     auto hasBoundDecls = !payloadVars.empty();
-    std::optional<MutableArrayRef<VarDecl *>> caseBodyVarDecls;
+    ArrayRef<VarDecl *> caseBodyVarDecls;
     if (hasBoundDecls) {
       auto copy = C.Allocate<VarDecl *>(payloadVars.size());
       for (unsigned i : indices(payloadVars)) {
@@ -747,7 +747,7 @@ deriveBodyHashable_enum_hasAssociatedValues_hashInto(
         vNew->setImplicit();
         copy[i] = vNew;
       }
-      caseBodyVarDecls.emplace(copy);
+      caseBodyVarDecls = copy;
     }
 
     auto body = BraceStmt::create(C, SourceLoc(), statements, SourceLoc());
diff --git a/lib/Sema/MiscDiagnostics.cpp b/lib/Sema/MiscDiagnostics.cpp
@@ -3459,7 +3459,7 @@ class VarDeclUsageChecker : public ASTWalker {
 
     // Make sure that we setup our case body variables.
     if (auto *caseStmt = dyn_cast<CaseStmt>(S)) {
-      for (auto *vd : caseStmt->getCaseBodyVariablesOrEmptyArray()) {
+      for (auto *vd : caseStmt->getCaseBodyVariables()) {
         VarDecls[vd] |= RK_Defined;
       }
     }
diff --git a/lib/Sema/TypeCheckStmt.cpp b/lib/Sema/TypeCheckStmt.cpp
@@ -126,7 +126,7 @@ namespace {
       // The ASTWalker doesn't walk the case body variables, contextualize them
       // ourselves.
       if (auto *CS = dyn_cast<CaseStmt>(S)) {
-        for (auto *CaseVar : CS->getCaseBodyVariablesOrEmptyArray())
+        for (auto *CaseVar : CS->getCaseBodyVariables())
           CaseVar->setDeclContext(ParentDC);
       }
       // A few statements store DeclContexts, update them.
@@ -341,7 +341,7 @@ namespace {
 
     PreWalkResult<Stmt *> walkToStmtPre(Stmt *S) override {
       if (auto caseStmt = dyn_cast<CaseStmt>(S)) {
-        for (auto var : caseStmt->getCaseBodyVariablesOrEmptyArray())
+        for (auto var : caseStmt->getCaseBodyVariables())
           setLocalDiscriminator(var);
       }
       return Action::Continue(S);
@@ -970,7 +970,7 @@ bool swift::checkFallthroughStmt(FallthroughStmt *FS) {
   // decls. So if we match against the case body var decls,
   // transitively we will match all of the other case label items in
   // the fallthrough destination as well.
-  auto previousVars = previousBlock->getCaseBodyVariablesOrEmptyArray();
+  auto previousVars = previousBlock->getCaseBodyVariables();
   for (auto *expected : vars) {
     bool matched = false;
     if (!expected->hasName())
@@ -1600,7 +1600,7 @@ class StmtChecker : public StmtVisitor<StmtChecker, Stmt*> {
       }
 
       // Setup the types of our case body var decls.
-      for (auto *expected : caseBlock->getCaseBodyVariablesOrEmptyArray()) {
+      for (auto *expected : caseBlock->getCaseBodyVariables()) {
         assert(expected->hasName());
         auto prev = expected->getParentVarDecl();
         if (prev->hasInterfaceType())
@@ -3302,7 +3302,7 @@ void swift::bindSwitchCasePatternVars(DeclContext *dc, CaseStmt *caseStmt) {
   }
 
   // Wire up the case body variables to the latest patterns.
-  for (auto bodyVar : caseStmt->getCaseBodyVariablesOrEmptyArray()) {
+  for (auto bodyVar : caseStmt->getCaseBodyVariables()) {
     recordVar(nullptr, bodyVar);
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -378,10 +378,10 @@ bool CaseLabelItemScope::lookupLocalsOrMembers(DeclConsumer consumer) const {`
`378`	`378`	`}`
`379`	`379`
`380`	`380`	`bool CaseStmtBodyScope::lookupLocalsOrMembers(DeclConsumer consumer) const {`
`381`		`- for (auto *var : stmt->getCaseBodyVariablesOrEmptyArray())`
	`381`	`+ for (auto *var : stmt->getCaseBodyVariables()) {`
`382`	`382`	`if (consumer.consume({var}))`
`383`		`- return true;`
`384`		`-`
	`383`	`+ return true;`
	`384`	`+ }`
`385`	`385`	`return false;`
`386`	`386`	`}`
`387`	`387`
Original file line number	Diff line number	Diff line change
`@@ -946,7 +946,7 @@ createEnumSwitch(ASTContext &C, DeclContext DC, Expr expr, EnumDecl *enumDecl,`
`946`	`946`	`// .<elt>(let a0, let a1, ...)`
`947`	`947`	`SmallVector<VarDecl *, 3> payloadVars;`
`948`	`948`	`Pattern *subpattern = nullptr;`
`949`		`- std::optional<MutableArrayRef<VarDecl *>> caseBodyVarDecls;`
	`949`	`+ ArrayRef<VarDecl *> caseBodyVarDecls;`
`950`	`950`
`951`	`951`	`if (createSubpattern) {`
`952`	`952`	`subpattern = DerivedConformance::enumElementPayloadSubpattern(`
`@@ -965,7 +965,7 @@ createEnumSwitch(ASTContext &C, DeclContext DC, Expr expr, EnumDecl *enumDecl,`
`965`	`965`	`vNew->setImplicit();`
`966`	`966`	`copy[i] = vNew;`
`967`	`967`	`}`
`968`		`- caseBodyVarDecls.emplace(copy);`
	`968`	`+ caseBodyVarDecls = copy;`
`969`	`969`	`}`
`970`	`970`	`}`
`971`	`971`
`@@ -988,8 +988,7 @@ createEnumSwitch(ASTContext &C, DeclContext DC, Expr expr, EnumDecl *enumDecl,`
`988`	`988`	`auto stmt =`
`989`	`989`	`CaseStmt::create(C, CaseParentKind::Switch, SourceLoc(), labelItem,`
`990`	`990`	`SourceLoc(), SourceLoc(), caseBody,`
`991`		`- /case body vardecls/`
`992`		`- createSubpattern ? caseBodyVarDecls : std::nullopt);`
	`991`	`+ caseBodyVarDecls);`
`993`	`992`	`cases.push_back(stmt);`
`994`	`993`	`}`
`995`	`994`	`}`