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[clang][Sema] Cleanup and optimize DiagnoseAssignmentEnum #141471

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May 28, 2025
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[clang][Sema] Cleanup and optimize DiagnoseAssignmentEnum #141471

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[clang][Sema] Cleanup and optimize DiagnoseAssignmentEnum
tbaederr May 26, 2025
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tbaederr May 26, 2025
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98 changes: 53 additions & 45 deletions clang/lib/Sema/SemaStmt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1741,57 +1741,65 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
void
Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
Expr *SrcExpr) {

const auto *ET = DstType->getAs<EnumType>();
if (!ET)
return;

if (!SrcType->isIntegerType() ||
Context.hasSameUnqualifiedType(SrcType, DstType))
return;

if (SrcExpr->isTypeDependent() || SrcExpr->isValueDependent())
return;

const EnumDecl *ED = ET->getDecl();
if (!ED->isClosed())
return;

if (Diags.isIgnored(diag::warn_not_in_enum_assignment, SrcExpr->getExprLoc()))
return;

if (const EnumType *ET = DstType->getAs<EnumType>())
if (!Context.hasSameUnqualifiedType(SrcType, DstType) &&
SrcType->isIntegerType()) {
if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
SrcExpr->isIntegerConstantExpr(Context)) {
// Get the bitwidth of the enum value before promotions.
unsigned DstWidth = Context.getIntWidth(DstType);
bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
std::optional<llvm::APSInt> RHSVal = SrcExpr->getIntegerConstantExpr(Context);
if (!RHSVal)
return;

llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context);
AdjustAPSInt(RhsVal, DstWidth, DstIsSigned);
const EnumDecl *ED = ET->getDecl();
// Get the bitwidth of the enum value before promotions.
unsigned DstWidth = Context.getIntWidth(DstType);
bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
AdjustAPSInt(*RHSVal, DstWidth, DstIsSigned);

if (!ED->isClosed())
return;
if (ED->hasAttr<FlagEnumAttr>()) {
if (!IsValueInFlagEnum(ED, *RHSVal, /*AllowMask=*/true))
Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
<< DstType.getUnqualifiedType();
return;
}

if (ED->hasAttr<FlagEnumAttr>()) {
if (!IsValueInFlagEnum(ED, RhsVal, true))
Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
<< DstType.getUnqualifiedType();
} else {
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 (auto *EDI : ED->enumerators()) {
llvm::APSInt Val = EDI->getInitVal();
AdjustAPSInt(Val, DstWidth, DstIsSigned);
EnumVals.push_back(std::make_pair(Val, EDI));
}
if (EnumVals.empty())
return;
llvm::stable_sort(EnumVals, CmpEnumVals);
EnumValsTy::iterator EIend = llvm::unique(EnumVals, EqEnumVals);

// See which values aren't in the 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_assignment)
<< DstType.getUnqualifiedType();
}
}
}
}
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 (auto *EDI : ED->enumerators()) {
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It would be interesting to test the case in which we have a enum and the enumerators values are out of order to verify the sorting actually works as expected e.g.

enum E {
  E1 = 100,
  E2 = 50,
  E3 = 75,
  E4 = 9,
  E5 = 99
};

I don't see a test that verifies that but I could be missing it.

llvm::APSInt Val = EDI->getInitVal();
AdjustAPSInt(Val, DstWidth, DstIsSigned);
EnumVals.emplace_back(Val, EDI);
}
if (EnumVals.empty())
return;
llvm::stable_sort(EnumVals, CmpEnumVals);
EnumValsTy::iterator EIend = llvm::unique(EnumVals, EqEnumVals);

// See which values aren't in the 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_assignment)
<< DstType.getUnqualifiedType();
}
}

StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc,
Expand Down