Refactor checking of switch conditions and case values.

Check each case value in turn while parsing it, performing the
conversion to the switch type within the context of the expression
itself. This will become necessary in order to properly handle cleanups
for temporaries created as part of the case label (in an upcoming
patch). For now it's just good hygiene.

This necessitates moving the checking for the switch condition itself to
earlier, so that the destination type is available when checking the
case labels.

As a nice side-effect, we get slightly improved diagnostic quality and
error recovery by separating the case expression checking from the case
statement checking and from tracking whether there are discarded case
labels.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@338056 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Parse/Parser.h

@@ -1578,6 +1578,7 @@ public:
   ExprResult ParseConstantExpressionInExprEvalContext(
       TypeCastState isTypeCast = NotTypeCast);
   ExprResult ParseConstantExpression(TypeCastState isTypeCast = NotTypeCast);
+  ExprResult ParseCaseExpression(SourceLocation CaseLoc);
   ExprResult ParseConstraintExpression();
   // Expr that doesn't include commas.
   ExprResult ParseAssignmentExpression(TypeCastState isTypeCast = NotTypeCast);

include/clang/Sema/ScopeInfo.h

@@ -175,9 +175,13 @@ public:
   /// Used to determine if errors occurred in this function or block.
   DiagnosticErrorTrap ErrorTrap;
 
+  /// A SwitchStmt, along with a flag indicating if its list of case statements
+  /// is incomplete (because we dropped an invalid one while parsing).
+  using SwitchInfo = llvm::PointerIntPair<SwitchStmt*, 1, bool>;
+
   /// SwitchStack - This is the current set of active switch statements in the
   /// block.
-  SmallVector<SwitchStmt*, 8> SwitchStack;
+  SmallVector<SwitchInfo, 8> SwitchStack;
 
   /// The list of return statements that occur within the function or
   /// block, if there is any chance of applying the named return value

include/clang/Sema/Sema.h

@@ -3727,9 +3727,10 @@ public:
                                    SourceLocation EndLoc);
   void ActOnForEachDeclStmt(DeclGroupPtrTy Decl);
   StmtResult ActOnForEachLValueExpr(Expr *E);
-  StmtResult ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
-                                   SourceLocation DotDotDotLoc, Expr *RHSVal,
-                                   SourceLocation ColonLoc);
+  ExprResult ActOnCaseExpr(SourceLocation CaseLoc, ExprResult Val);
+  StmtResult ActOnCaseStmt(SourceLocation CaseLoc, ExprResult LHS,
+                           SourceLocation DotDotDotLoc, ExprResult RHS,
+                           SourceLocation ColonLoc);
   void ActOnCaseStmtBody(Stmt *CaseStmt, Stmt *SubStmt);
 
   StmtResult ActOnDefaultStmt(SourceLocation DefaultLoc,

lib/Parse/ParseExpr.cpp

@@ -217,6 +217,14 @@ ExprResult Parser::ParseConstantExpression(TypeCastState isTypeCast) {
   return ParseConstantExpressionInExprEvalContext(isTypeCast);
 }
 
+ExprResult Parser::ParseCaseExpression(SourceLocation CaseLoc) {
+  EnterExpressionEvaluationContext ConstantEvaluated(
+      Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+  ExprResult LHS(ParseCastExpression(false, false, NotTypeCast));
+  ExprResult Res(ParseRHSOfBinaryExpression(LHS, prec::Conditional));
+  return Actions.ActOnCaseExpr(CaseLoc, Res);
+}
+
 /// Parse a constraint-expression.
 ///
 /// \verbatim

lib/Parse/ParseStmt.cpp

@@ -685,20 +685,12 @@ StmtResult Parser::ParseCaseStatement(bool MissingCase, ExprResult Expr) {
 
     ExprResult LHS;
     if (!MissingCase) {
-      LHS = ParseConstantExpression();
-      if (!getLangOpts().CPlusPlus11) {
-        LHS = Actions.CorrectDelayedTyposInExpr(LHS, [this](class Expr *E) {
-          return Actions.VerifyIntegerConstantExpression(E);
-        });
-      }
+      LHS = ParseCaseExpression(CaseLoc);
       if (LHS.isInvalid()) {
         // If constant-expression is parsed unsuccessfully, recover by skipping
         // current case statement (moving to the colon that ends it).
-        if (SkipUntil(tok::colon, tok::r_brace, StopAtSemi | StopBeforeMatch)) {
-          TryConsumeToken(tok::colon, ColonLoc);
-          continue;
-        }
-        return StmtError();
+        if (!SkipUntil(tok::colon, tok::r_brace, StopAtSemi | StopBeforeMatch))
+          return StmtError();
       }
     } else {
       LHS = Expr;
@@ -710,13 +702,10 @@ StmtResult Parser::ParseCaseStatement(bool MissingCase, ExprResult Expr) {
     ExprResult RHS;
     if (TryConsumeToken(tok::ellipsis, DotDotDotLoc)) {
       Diag(DotDotDotLoc, diag::ext_gnu_case_range);
-      RHS = ParseConstantExpression();
+      RHS = ParseCaseExpression(CaseLoc);
       if (RHS.isInvalid()) {
-        if (SkipUntil(tok::colon, tok::r_brace, StopAtSemi | StopBeforeMatch)) {
-          TryConsumeToken(tok::colon, ColonLoc);
-          continue;
-        }
-        return StmtError();
+        if (!SkipUntil(tok::colon, tok::r_brace, StopAtSemi | StopBeforeMatch))
+          return StmtError();
       }
     }
 
@@ -738,8 +727,7 @@ StmtResult Parser::ParseCaseStatement(bool MissingCase, ExprResult Expr) {
     }
 
     StmtResult Case =
-      Actions.ActOnCaseStmt(CaseLoc, LHS.get(), DotDotDotLoc,
-                            RHS.get(), ColonLoc);
+        Actions.ActOnCaseStmt(CaseLoc, LHS, DotDotDotLoc, RHS, ColonLoc);
 
     // If we had a sema error parsing this case, then just ignore it and
     // continue parsing the sub-stmt.

lib/Sema/SemaCodeComplete.cpp

@@ -4316,7 +4316,7 @@ void Sema::CodeCompleteCase(Scope *S) {
   if (getCurFunction()->SwitchStack.empty() || !CodeCompleter)
     return;
 
-  SwitchStmt *Switch = getCurFunction()->SwitchStack.back();
+  SwitchStmt *Switch = getCurFunction()->SwitchStack.back().getPointer();
   QualType type = Switch->getCond()->IgnoreImplicit()->getType();
   if (!type->isEnumeralType()) {
     CodeCompleteExpressionData Data(type);

lib/Sema/SemaStmt.cpp

@@ -392,65 +392,79 @@ StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
   return CompoundStmt::Create(Context, Elts, L, R);
 }
 
+ExprResult
+Sema::ActOnCaseExpr(SourceLocation CaseLoc, ExprResult Val) {
+  if (!Val.get())
+    return Val;
+
+  if (DiagnoseUnexpandedParameterPack(Val.get()))
+    return ExprError();
+
+  // If we're not inside a switch, let the 'case' statement handling diagnose
+  // this. Just clean up after the expression as best we can.
+  if (!getCurFunction()->SwitchStack.empty()) {
+    Expr *CondExpr =
+        getCurFunction()->SwitchStack.back().getPointer()->getCond();
+    if (!CondExpr)
+      return ExprError();
+    QualType CondType = CondExpr->getType();
+
+    auto CheckAndFinish = [&](Expr *E) {
+      if (CondType->isDependentType() || E->isTypeDependent())
+        return ExprResult(E);
+
+      if (getLangOpts().CPlusPlus11) {
+        // C++11 [stmt.switch]p2: the constant-expression shall be a converted
+        // constant expression of the promoted type of the switch condition.
+        llvm::APSInt TempVal;
+        return CheckConvertedConstantExpression(E, CondType, TempVal,
+                                                CCEK_CaseValue);
+      }
+
+      ExprResult ER = E;
+      if (!E->isValueDependent())
+        ER = VerifyIntegerConstantExpression(E);
+      if (!ER.isInvalid())
+        ER = DefaultLvalueConversion(ER.get());
+      if (!ER.isInvalid())
+        ER = ImpCastExprToType(ER.get(), CondType, CK_IntegralCast);
+      return ER;
+    };
+
+    ExprResult Converted = CorrectDelayedTyposInExpr(Val, CheckAndFinish);
+    if (Converted.get() == Val.get())
+      Converted = CheckAndFinish(Val.get());
+    if (Converted.isInvalid())
+      return ExprError();
+    Val = Converted;
+  }
+
+  return ActOnFinishFullExpr(Val.get(), Val.get()->getExprLoc(), false,
+                             getLangOpts().CPlusPlus11);
+}
+
 StmtResult
-Sema::ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
-                    SourceLocation DotDotDotLoc, Expr *RHSVal,
+Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprResult LHSVal,
+                    SourceLocation DotDotDotLoc, ExprResult RHSVal,
                     SourceLocation ColonLoc) {
-  assert(LHSVal && "missing expression in case statement");
+  assert((LHSVal.isInvalid() || LHSVal.get()) && "missing LHS value");
+  assert((DotDotDotLoc.isInvalid() ? RHSVal.isUnset()
+                                   : RHSVal.isInvalid() || RHSVal.get()) &&
+         "missing RHS value");
 
   if (getCurFunction()->SwitchStack.empty()) {
     Diag(CaseLoc, diag::err_case_not_in_switch);
     return StmtError();
   }
 
-  ExprResult LHS =
-      CorrectDelayedTyposInExpr(LHSVal, [this](class Expr *E) {
-        if (!getLangOpts().CPlusPlus11)
-          return VerifyIntegerConstantExpression(E);
-        if (Expr *CondExpr =
-                getCurFunction()->SwitchStack.back()->getCond()) {
-          QualType CondType = CondExpr->getType();
-          llvm::APSInt TempVal;
-          return CheckConvertedConstantExpression(E, CondType, TempVal,
-                                                        CCEK_CaseValue);
-        }
-        return ExprError();
-      });
-  if (LHS.isInvalid())
+  if (LHSVal.isInvalid() || RHSVal.isInvalid()) {
+    getCurFunction()->SwitchStack.back().setInt(true);
     return StmtError();
-  LHSVal = LHS.get();
-
-  if (!getLangOpts().CPlusPlus11) {
-    // C99 6.8.4.2p3: The expression shall be an integer constant.
-    // However, GCC allows any evaluatable integer expression.
-    if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent()) {
-      LHSVal = VerifyIntegerConstantExpression(LHSVal).get();
-      if (!LHSVal)
-        return StmtError();
-    }
-
-    // GCC extension: The expression shall be an integer constant.
-
-    if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent()) {
-      RHSVal = VerifyIntegerConstantExpression(RHSVal).get();
-      // Recover from an error by just forgetting about it.
-    }
   }
 
-  LHS = ActOnFinishFullExpr(LHSVal, LHSVal->getExprLoc(), false,
-                                 getLangOpts().CPlusPlus11);
-  if (LHS.isInvalid())
-    return StmtError();
-
-  auto RHS = RHSVal ? ActOnFinishFullExpr(RHSVal, RHSVal->getExprLoc(), false,
-                                          getLangOpts().CPlusPlus11)
-                    : ExprResult();
-  if (RHS.isInvalid())
-    return StmtError();
-
   CaseStmt *CS = new (Context)
-      CaseStmt(LHS.get(), RHS.get(), CaseLoc, DotDotDotLoc, ColonLoc);
-  getCurFunction()->SwitchStack.back()->addSwitchCase(CS);
+      CaseStmt(LHSVal.get(), RHSVal.get(), CaseLoc, DotDotDotLoc, ColonLoc);
+  getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(CS);
   return CS;
 }
 
@@ -473,7 +487,7 @@ Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
   }
 
   DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
-  getCurFunction()->SwitchStack.back()->addSwitchCase(DS);
+  getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(DS);
   return DS;
 }
 
@@ -679,20 +693,44 @@ ExprResult Sema::CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond) {
   if (CondResult.isInvalid())
     return ExprError();
 
+  // FIXME: PerformContextualImplicitConversion doesn't always tell us if it
+  // failed and produced a diagnostic.
+  Cond = CondResult.get();
+  if (!Cond->isTypeDependent() &&
+      !Cond->getType()->isIntegralOrEnumerationType())
+    return ExprError();
+
   // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
-  return UsualUnaryConversions(CondResult.get());
+  return UsualUnaryConversions(Cond);
 }
 
 StmtResult Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,
                                         Stmt *InitStmt, ConditionResult Cond) {
-  if (Cond.isInvalid())
-    return StmtError();
+  Expr *CondExpr = Cond.get().second;
+  assert((Cond.isInvalid() || CondExpr) && "switch with no condition");
+
+  if (CondExpr && !CondExpr->isTypeDependent()) {
+    // We have already converted the expression to an integral or enumeration
+    // type, when we parsed the switch condition. If we don't have an
+    // appropriate type now, enter the switch scope but remember that it's
+    // invalid.
+    assert(CondExpr->getType()->isIntegralOrEnumerationType() &&
+           "invalid condition type");
+    if (CondExpr->isKnownToHaveBooleanValue()) {
+      // switch(bool_expr) {...} is often a programmer error, e.g.
+      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
+      // One can always use an if statement instead of switch(bool_expr).
+      Diag(SwitchLoc, diag::warn_bool_switch_condition)
+          << CondExpr->getSourceRange();
+    }
+  }
 
   setFunctionHasBranchIntoScope();
 
   SwitchStmt *SS = new (Context)
-      SwitchStmt(Context, InitStmt, Cond.get().first, Cond.get().second);
-  getCurFunction()->SwitchStack.push_back(SS);
+      SwitchStmt(Context, InitStmt, Cond.get().first, CondExpr);
+  getCurFunction()->SwitchStack.push_back(
+      FunctionScopeInfo::SwitchInfo(SS, false));
   return SS;
 }
 
@@ -705,6 +743,10 @@ static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
 /// type.
 static void checkCaseValue(Sema &S, SourceLocation Loc, const llvm::APSInt &Val,
                            unsigned UnpromotedWidth, bool UnpromotedSign) {
+  // In C++11 onwards, this is checked by the language rules.
+  if (S.getLangOpts().CPlusPlus11)
+    return;
+
   // If the case value was signed and negative and the switch expression is
   // unsigned, don't bother to warn: this is implementation-defined behavior.
   // FIXME: Introduce a second, default-ignored warning for this case?
@@ -759,7 +801,7 @@ static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
 
 static void checkEnumTypesInSwitchStmt(Sema &S, const Expr *Cond,
                                        const Expr *Case) {
-  QualType CondType = GetTypeBeforeIntegralPromotion(Cond);
+  QualType CondType = Cond->getType();
   QualType CaseType = Case->getType();
 
   const EnumType *CondEnumType = CondType->getAs<EnumType>();
@@ -787,7 +829,8 @@ StmtResult
 Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
                             Stmt *BodyStmt) {
   SwitchStmt *SS = cast<SwitchStmt>(Switch);
-  assert(SS == getCurFunction()->SwitchStack.back() &&
+  bool CaseListIsIncomplete = getCurFunction()->SwitchStack.back().getInt();
+  assert(SS == getCurFunction()->SwitchStack.back().getPointer() &&
          "switch stack missing push/pop!");
 
   getCurFunction()->SwitchStack.pop_back();
@@ -800,10 +843,6 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
 
   QualType CondType = CondExpr->getType();
 
-  const Expr *CondExprBeforePromotion = CondExpr;
-  QualType CondTypeBeforePromotion =
-      GetTypeBeforeIntegralPromotion(CondExprBeforePromotion);
-
   // C++ 6.4.2.p2:
   // Integral promotions are performed (on the switch condition).
   //
@@ -811,21 +850,9 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
   // type (before the promotion) doesn't make sense, even when it can
   // be represented by the promoted type.  Therefore we need to find
   // the pre-promotion type of the switch condition.
-  if (!CondExpr->isTypeDependent()) {
-    // We have already converted the expression to an integral or enumeration
-    // type, when we started the switch statement. If we don't have an
-    // appropriate type now, just return an error.
-    if (!CondType->isIntegralOrEnumerationType())
-      return StmtError();
-
-    if (CondExpr->isKnownToHaveBooleanValue()) {
-      // switch(bool_expr) {...} is often a programmer error, e.g.
-      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
-      // One can always use an if statement instead of switch(bool_expr).
-      Diag(SwitchLoc, diag::warn_bool_switch_condition)
-          << CondExpr->getSourceRange();
-    }
-  }
+  const Expr *CondExprBeforePromotion = CondExpr;
+  QualType CondTypeBeforePromotion =
+      GetTypeBeforeIntegralPromotion(CondExprBeforePromotion);
 
   // Get the bitwidth of the switched-on value after promotions. We must
   // convert the integer case values to this width before comparison.
@@ -878,50 +905,32 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
 
       Expr *Lo = CS->getLHS();
 
-      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
+      if (Lo->isValueDependent()) {
         HasDependentValue = true;
         break;
       }
 
-      checkEnumTypesInSwitchStmt(*this, CondExpr, Lo);
-
-      llvm::APSInt LoVal;
-
-      if (getLangOpts().CPlusPlus11) {
-        // C++11 [stmt.switch]p2: the constant-expression shall be a converted
-        // constant expression of the promoted type of the switch condition.
-        ExprResult ConvLo =
-          CheckConvertedConstantExpression(Lo, CondType, LoVal, CCEK_CaseValue);
-        if (ConvLo.isInvalid()) {
-          CaseListIsErroneous = true;
-          continue;
-        }
-        Lo = ConvLo.get();
-      } else {
-        // We already verified that the expression has a i-c-e value (C99
-        // 6.8.4.2p3) - get that value now.
-        LoVal = Lo->EvaluateKnownConstInt(Context);
-
-        // If the LHS is not the same type as the condition, insert an implicit
-        // cast.
-        Lo = DefaultLvalueConversion(Lo).get();
-        Lo = ImpCastExprToType(Lo, CondType, CK_IntegralCast).get();
-      }
+      // We already verified that the expression has a constant value;
+      // get that value (prior to conversions).
+      const Expr *LoBeforePromotion = Lo;
+      GetTypeBeforeIntegralPromotion(LoBeforePromotion);
+      llvm::APSInt LoVal = LoBeforePromotion->EvaluateKnownConstInt(Context);
 
       // Check the unconverted value is within the range of possible values of
       // the switch expression.
       checkCaseValue(*this, Lo->getLocStart(), LoVal,
                      CondWidthBeforePromotion, CondIsSignedBeforePromotion);
 
+      // FIXME: This duplicates the check performed for warn_not_in_enum below.
+      checkEnumTypesInSwitchStmt(*this, CondExprBeforePromotion,
+                                 LoBeforePromotion);
+
       // Convert the value to the same width/sign as the condition.
       AdjustAPSInt(LoVal, CondWidth, CondIsSigned);
 
-      CS->setLHS(Lo);
-
       // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
       if (CS->getRHS()) {
-        if (CS->getRHS()->isTypeDependent() ||
-            CS->getRHS()->isValueDependent()) {
+        if (CS->getRHS()->isValueDependent()) {
           HasDependentValue = true;
           break;
         }
@@ -1002,27 +1011,10 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
         llvm::APSInt &LoVal = CaseRanges[i].first;
         CaseStmt *CR = CaseRanges[i].second;
         Expr *Hi = CR->getRHS();
-        llvm::APSInt HiVal;
-
-        if (getLangOpts().CPlusPlus11) {
-          // C++11 [stmt.switch]p2: the constant-expression shall be a converted
-          // constant expression of the promoted type of the switch condition.
-          ExprResult ConvHi =
-            CheckConvertedConstantExpression(Hi, CondType, HiVal,
-                                             CCEK_CaseValue);
-          if (ConvHi.isInvalid()) {
-            CaseListIsErroneous = true;
-            continue;
-          }
-          Hi = ConvHi.get();
-        } else {
-          HiVal = Hi->EvaluateKnownConstInt(Context);
 
-          // If the RHS is not the same type as the condition, insert an
-          // implicit cast.
-          Hi = DefaultLvalueConversion(Hi).get();
-          Hi = ImpCastExprToType(Hi, CondType, CK_IntegralCast).get();
-        }
+        const Expr *HiBeforePromotion = Hi;
+        GetTypeBeforeIntegralPromotion(HiBeforePromotion);
+        llvm::APSInt HiVal = HiBeforePromotion->EvaluateKnownConstInt(Context);
 
         // Check the unconverted value is within the range of possible values of
         // the switch expression.
@@ -1032,8 +1024,6 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
         // Convert the value to the same width/sign as the condition.
         AdjustAPSInt(HiVal, CondWidth, CondIsSigned);
 
-        CR->setRHS(Hi);
-
         // If the low value is bigger than the high value, the case is empty.
         if (LoVal > HiVal) {
           Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
@@ -1104,7 +1094,8 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
     }
 
     // Complain if we have a constant condition and we didn't find a match.
-    if (!CaseListIsErroneous && ShouldCheckConstantCond) {
+    if (!CaseListIsErroneous && !CaseListIsIncomplete &&
+        ShouldCheckConstantCond) {
       // TODO: it would be nice if we printed enums as enums, chars as
       // chars, etc.
       Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
@@ -1120,8 +1111,8 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
     const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
 
     // If switch has default case, then ignore it.
-    if (!CaseListIsErroneous && !HasConstantCond && ET &&
-        ET->getDecl()->isCompleteDefinition()) {
+    if (!CaseListIsErroneous && !CaseListIsIncomplete && !HasConstantCond &&
+        ET && ET->getDecl()->isCompleteDefinition()) {
       const EnumDecl *ED = ET->getDecl();
       EnumValsTy EnumVals;
 

lib/Sema/TreeTransform.h

@@ -6525,13 +6525,13 @@ TreeTransform<Derived>::TransformCaseStmt(CaseStmt *S) {
 
     // Transform the left-hand case value.
     LHS = getDerived().TransformExpr(S->getLHS());
-    LHS = SemaRef.ActOnConstantExpression(LHS);
+    LHS = SemaRef.ActOnCaseExpr(S->getCaseLoc(), LHS);
     if (LHS.isInvalid())
       return StmtError();
 
     // Transform the right-hand case value (for the GNU case-range extension).
     RHS = getDerived().TransformExpr(S->getRHS());
-    RHS = SemaRef.ActOnConstantExpression(RHS);
+    RHS = SemaRef.ActOnCaseExpr(S->getCaseLoc(), RHS);
     if (RHS.isInvalid())
       return StmtError();
   }

test/Parser/switch-recovery.cpp

@@ -185,8 +185,9 @@ void pr19022_1a(int x) {
 
 void pr19022_1b(int x) {
   switch(x) {
-  case v  // expected-error{{use of undeclared identifier 'v'}}
-  }
+  case v  // expected-error{{use of undeclared identifier 'v'}} \
+          // expected-error{{expected ':' after 'case'}}
+  } // expected-error{{expected statement}}
  }
 
 void pr19022_2() {
@@ -209,7 +210,8 @@ int pr19022_4(int x) {
 
 void pr19022_5(int x) {
   switch(x) {
-  case 1: case
+  case 1: case // expected-error{{expected ':' after 'case'}} \
+               // expected-error{{expected statement}}
   }  // expected-error{{expected expression}}
 }
 

test/Sema/complex-int.c

@@ -18,6 +18,10 @@ result = arr*brr;
 result = xx*yy;
 
 switch (arr) { // expected-error{{statement requires expression of integer type ('_Complex int' invalid)}}
+  case brr: ;
+  case xx: ;
+}
+switch (ii) {
   case brr: ; // expected-error{{expression is not an integer constant expression}}
   case xx: ; // expected-error{{expression is not an integer constant expression}}
 }

test/Sema/switch.c

@@ -372,7 +372,7 @@ void switch_on_ExtendedEnum1(enum ExtendedEnum1 e) {
   case EE1_b: break;
   case EE1_c: break; // no-warning
   case EE1_d: break; // expected-warning {{case value not in enumerated type 'enum ExtendedEnum1'}}
-  // expected-warning@-1 {{comparison of two values with different enumeration types in switch statement ('enum ExtendedEnum1' and 'const enum ExtendedEnum1_unrelated')}}
+  // expected-warning@-1 {{comparison of two values with different enumeration types in switch statement ('enum ExtendedEnum1' and 'enum ExtendedEnum1_unrelated')}}
   }
 }
 

test/SemaCXX/i-c-e-cxx.cpp

@@ -23,10 +23,8 @@ int a() {
   // expected-note@-2 {{read of object outside its lifetime}}
 #endif
 
-  switch(1) {
-#if __cplusplus <= 199711L
-  // expected-warning@-2 {{no case matching constant switch condition '1'}}
-#endif
+  switch(1) { // do not warn that 1 is not a case value;
+              // 't' might have been expected to evalaute to 1
     case t:; // expected-note {{initializer of 't' is not a constant expression}}
 #if __cplusplus <= 199711L
     // expected-error@-2 {{not an integral constant expression}}

test/SemaCXX/scope-check.cpp

@@ -193,7 +193,8 @@ namespace PR10462 {
 
   bool recurse() {
     MyEnum K;
-    switch (K) { // expected-warning {{enumeration value 'something_invalid' not handled in switch}}
+    switch (K) { // do not warn that 'something_invalid' is not listed;
+                 // 'what_am_i_thinking' might have been intended to be that case.
     case something_valid:
     case what_am_i_thinking: // expected-error {{use of undeclared identifier}}
       int *X = 0;

test/SemaCXX/typo-correction.cpp

@@ -411,7 +411,7 @@ public:
 
 void testAccess() {
   Figure obj;
-  switch (obj.type()) {  // expected-warning {{enumeration values 'SQUARE', 'TRIANGLE', and 'CIRCLE' not handled in switch}}
+  switch (obj.type()) {
   case SQUARE:  // expected-error-re {{use of undeclared identifier 'SQUARE'{{$}}}}
   case TRIANGLE:  // expected-error-re {{use of undeclared identifier 'TRIANGLE'{{$}}}}
   case CIRCE:  // expected-error-re {{use of undeclared identifier 'CIRCE'{{$}}}}