trivial patch, improve constness

[danielmarjamaki]

Summary

this trivial patch improves constness. it makes it possible to use these utility functions for constant expressions also.

[meadori]

Overall this looks reasonable to me and consistent with the style for the rest of this file (which uses const when possible also). One minor comment inline.

lib/Sema/SemaChecking.cpp

6048

Seems like all these casts would be better of with const auto?

[danielmarjamaki]

minor update, use auto instead of explicit type

[danielmarjamaki]

ping. can somebody review?

[danielmarjamaki]

ping.. can somebody review.

[aaron.ballman]

LGTM!

[danielmarjamaki]

Thanks! Committed with r258673

lib/Sema/SemaChecking.cpp

static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
   // Assume it might use arbitrary bits.
   // FIXME: The only reason we need to pass the type in here is to get
   // the sign right on this one case.  It would be nice if APValue
   // preserved this.
   assert(result.isLValue() || result.isAddrLabelDiff());
   return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
 }
 
-static QualType GetExprType(Expr *E) {
+static QualType GetExprType(const Expr *E) {
   QualType Ty = E->getType();
   if (const AtomicType *AtomicRHS = Ty->getAs<AtomicType>())
     Ty = AtomicRHS->getValueType();
   return Ty;
 }
 
 /// Pseudo-evaluate the given integer expression, estimating the
 /// range of values it might take.
 ///
 /// \param MaxWidth - the width to which the value will be truncated
-static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
+static IntRange GetExprRange(ASTContext &C, const Expr *E, unsigned MaxWidth) {
   E = E->IgnoreParens();
 
   // Try a full evaluation first.
   Expr::EvalResult result;
   if (E->EvaluateAsRValue(result, C))
     return GetValueRange(C, result.Val, GetExprType(E), MaxWidth);
 
   // I think we only want to look through implicit casts here; if the
   // user has an explicit widening cast, we should treat the value as
   // being of the new, wider type.
-  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
+  if (const auto *CE = dyn_cast<ImplicitCastExpr>(E)) {
     if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
       return GetExprRange(C, CE->getSubExpr(), MaxWidth);
 
     IntRange OutputTypeRange = IntRange::forValueOfType(C, GetExprType(CE));
 
     bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
 
     // Assume that non-integer casts can span the full range of the type.
if (SubRange.Width >= OutputTypeRange.Width)
       return OutputTypeRange;
 
     // Otherwise, we take the smaller width, and we're non-negative if
     // either the output type or the subexpr is.
     return IntRange(SubRange.Width,
                     SubRange.NonNegative || OutputTypeRange.NonNegative);
   }
 
-  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
+  if (const auto *CO = dyn_cast<ConditionalOperator>(E)) {
     // If we can fold the condition, just take that operand.
     bool CondResult;
     if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
       return GetExprRange(C, CondResult ? CO->getTrueExpr()
                                         : CO->getFalseExpr(),
                           MaxWidth);
 
     // Otherwise, conservatively merge.
     IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
     IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
     return IntRange::join(L, R);
   }
 
-  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
+  if (const auto *BO = dyn_cast<BinaryOperator>(E)) {
     switch (BO->getOpcode()) {
 
     // Boolean-valued operations are single-bit and positive.
     case BO_LAnd:
     case BO_LOr:
     case BO_LT:
     case BO_GT:
     case BO_LE:
if (const auto *BO = dyn_cast<BinaryOperator>(E)) {
 
     // The default case is to treat the operation as if it were closed
     // on the narrowest type that encompasses both operands.
     IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
     IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
     return IntRange::join(L, R);
   }
 
-  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
+  if (const auto *UO = dyn_cast<UnaryOperator>(E)) {
     switch (UO->getOpcode()) {
     // Boolean-valued operations are white-listed.
     case UO_LNot:
       return IntRange::forBoolType();
 
     // Operations with opaque sources are black-listed.
     case UO_Deref:
     case UO_AddrOf: // should be impossible
       return IntRange::forValueOfType(C, GetExprType(E));
 
     default:
       return GetExprRange(C, UO->getSubExpr(), MaxWidth);
     }
   }
 
-  if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(E))
+  if (const auto *OVE = dyn_cast<OpaqueValueExpr>(E))
     return GetExprRange(C, OVE->getSourceExpr(), MaxWidth);
 
-  if (FieldDecl *BitField = E->getSourceBitField())
+  if (const auto *BitField = E->getSourceBitField())
     return IntRange(BitField->getBitWidthValue(C),
                     BitField->getType()->isUnsignedIntegerOrEnumerationType());
 
   return IntRange::forValueOfType(C, GetExprType(E));
 }
 
-static IntRange GetExprRange(ASTContext &C, Expr *E) {
+static IntRange GetExprRange(ASTContext &C, const Expr *E) {
   return GetExprRange(C, E, C.getIntWidth(GetExprType(E)));
 }
 
 /// Checks whether the given value, which currently has the given
 /// source semantics, has the same value when coerced through the
 /// target semantics.
 static bool IsSameFloatAfterCast(const llvm::APFloat &value,
                                  const llvm::fltSemantics &Src,