Issue warning when assigning out-of-range integer values to enums.

Due to performance cost, this is an opt-in option placed
under -Wassign-enum. // rdar://11824807


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160382 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 53 insertions, 1 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 34fb9d06a7..915663e622 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -9617,7 +9617,10 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
   bool MayHaveFunctionDiff = false;
 
   switch (ConvTy) {
-  case Compatible: return false;
+  case Compatible:
+      DiagnoseAssignmentEnum(DstType, SrcType, SrcExpr);
+      return false;
+
   case PointerToInt:
     DiagKind = diag::ext_typecheck_convert_pointer_int;
     ConvHints.tryToFixConversion(SrcExpr, SrcType, DstType, *this);
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 54ec58af41..9affe9823a 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -1059,6 +1059,55 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
   return Owned(SS);
 }
 
+void
+Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
+                             Expr *SrcExpr) {
+  unsigned DIAG = diag::warn_not_in_enum_assignement;
+  if (Diags.getDiagnosticLevel(DIAG, SrcExpr->getExprLoc()) 
+      == DiagnosticsEngine::Ignored)
+    return;
+  
+  if (const EnumType *ET = DstType->getAs<EnumType>())
+    if (!Context.hasSameType(SrcType, DstType) &&
+        SrcType->isIntegerType()) {
+      if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
+          SrcExpr->isIntegerConstantExpr(Context)) {
+        // Get the bitwidth of the enum value before promotions.
+        unsigned DstWith = Context.getIntWidth(DstType);
+        bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
+
+        llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context);
+        const EnumDecl *ED = ET->getDecl();
+        typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64>
+        EnumValsTy;
+        EnumValsTy EnumVals;
+        
+        // Gather all enum values, set their type and sort them,
+        // allowing easier comparison with rhs constant.
+        for (EnumDecl::enumerator_iterator EDI = ED->enumerator_begin();
+             EDI != ED->enumerator_end(); ++EDI) {
+          llvm::APSInt Val = EDI->getInitVal();
+          AdjustAPSInt(Val, DstWith, DstIsSigned);
+          EnumVals.push_back(std::make_pair(Val, *EDI));
+        }
+        if (EnumVals.empty())
+          return;
+        std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
+        EnumValsTy::iterator EIend =
+        std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
+        
+        // See which case values aren't in enum.
+        EnumValsTy::const_iterator EI = EnumVals.begin();
+        while (EI != EIend && EI->first < RhsVal)
+          EI++;
+        if (EI == EIend || EI->first != RhsVal) {
+          Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignement)
+          << DstType;
+        }
+      }
+    }
+}
+
 StmtResult
 Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond,
                      Decl *CondVar, Stmt *Body) {