Unexpected-flag-enumerator-value fixes

Fixes include
- Recognize when a value is mask
- Recognize binary operator behind implict casts
- Recognize when a value is a ref to another value (DeclRefExpr)

2 files changed, 94 insertions, 5 deletions

diff --git a/src/checks/manuallevel/unexpected-flag-enumerator-value.cpp b/src/checks/manuallevel/unexpected-flag-enumerator-value.cpp
index 6d1bf226..76c7afa8 100644
--- a/src/checks/manuallevel/unexpected-flag-enumerator-value.cpp
+++ b/src/checks/manuallevel/unexpected-flag-enumerator-value.cpp
@@ -39,17 +39,55 @@ UnexpectedFlagEnumeratorValue::UnexpectedFlagEnumeratorValue(const std::string &
 {
 }
 
+static ConstantExpr* getConstantExpr(EnumConstantDecl *enCD)
+{
+    auto cexpr = dyn_cast_or_null<ConstantExpr>(enCD->getInitExpr());
+    if (cexpr)
+        return cexpr;
+    if (auto cast = dyn_cast_or_null<ImplicitCastExpr>(enCD->getInitExpr())) {
+        return dyn_cast_or_null<ConstantExpr>(cast->getSubExpr());
+    }
+    return nullptr;
+}
+
+static bool isBinaryOperatorExpression(ConstantExpr* cexpr)
+{
+    auto subExpr = cexpr->getSubExpr();
+    if (dyn_cast_or_null<BinaryOperator>(subExpr))
+        return true;
+
+    if (auto cast = dyn_cast_or_null<ImplicitCastExpr>(subExpr)) {
+        return dyn_cast_or_null<BinaryOperator>(cast->getSubExpr());
+    }
+    return false;
+}
+
+static bool isReferenceToEnumerator(ConstantExpr* cexpr)
+{
+    return dyn_cast_or_null<DeclRefExpr>(cexpr->getSubExpr());
+}
+
 static bool isIntentionallyNotPowerOf2(EnumConstantDecl *en) {
+    constexpr unsigned MinOnesToQualifyAsMask = 3;
+
+    const auto val = en->getInitVal();
+    if (val.isMask() && val.countTrailingOnes() >= MinOnesToQualifyAsMask)
+        return true;
+
+    if (val.isShiftedMask() && val.countPopulation() >= MinOnesToQualifyAsMask)
+        return true;
 
-    auto cexpr = dyn_cast_or_null<ConstantExpr>(clazy::getFirstChild(en->getInitExpr()));
+    if (en->getName().contains_lower("mask"))
+        return true;
+
+    auto *cexpr = getConstantExpr(en);
     if (!cexpr)
         return false;
 
-    if (auto binaryOp = dyn_cast_or_null<BinaryOperator>(cexpr->getSubExpr())) {
+    if (isBinaryOperatorExpression(cexpr))
         return true;
-    }
 
-    if (en->getName().contains_lower("mask"))
+    if (isReferenceToEnumerator(cexpr))
         return true;
 
     return false;
@@ -124,7 +162,7 @@ void UnexpectedFlagEnumeratorValue::VisitDecl(clang::Decl *decl)
 
     for (EnumConstantDecl* enumerator : enumerators) {
         const auto &initVal = enumerator->getInitVal();
-        if (!initVal.isPowerOf2() && !initVal.isNullValue() && !initVal.isNegative()){
+        if (!initVal.isPowerOf2() && !initVal.isNullValue() && !initVal.isNegative()) {
             if (isIntentionallyNotPowerOf2(enumerator))
                 continue;
             const auto value = enumerator->getInitVal().getLimitedValue();
diff --git a/tests/unexpected-flag-enumerator-value/main.cpp b/tests/unexpected-flag-enumerator-value/main.cpp
index 40d3e885..91856fc4 100644
--- a/tests/unexpected-flag-enumerator-value/main.cpp
+++ b/tests/unexpected-flag-enumerator-value/main.cpp
@@ -64,6 +64,13 @@ enum WithMasks
     Mask = 0x0000FFFF
 };
 
+enum RelationFlag {
+    Label         = 0x00000001,
+    Labelled      = 0x00000002,
+    Controller    = 0x00000004,
+    Controlled    = 0x00000008,
+    AllRelations  = 0xffffffff
+};
 
 enum class WithZero {
     Zero = 0,
@@ -90,3 +97,47 @@ enum class WithNegative
     V8 = 8,
     VFoo = -1
 };
+
+enum Filter {
+    Dirs        = 0x001,
+    Files       = 0x002,
+    Drives      = 0x004,
+    NoSymLinks  = 0x008,
+    AllEntries  = Dirs | Files | Drives,// Because of this -1, the type of this enum becomes signed and hence BinaryOp | doesn't need any implicit casts
+    TypeMask    = 0x00f,
+
+    NoFilter = -1
+};
+
+enum ComponentFormattingOption : unsigned int {
+    PrettyDecoded = 0x000000,
+    EncodeSpaces = 0x100000,
+    EncodeUnicode = 0x200000,
+    EncodeDelimiters = 0x400000 | 0x800000,
+    EncodeReserved = 0x1000000,
+    DecodeReserved = 0x2000000,
+    // 0x4000000 used to indicate full-decode mode
+
+    FullyEncoded = EncodeSpaces | EncodeUnicode | EncodeDelimiters | EncodeReserved,
+    FullyDecoded = FullyEncoded | DecodeReserved | 0x4000000
+};
+enum MarkdownFeature {
+    MarkdownNoHTML = 0x0020 | 0x0040,
+    MarkdownDialectCommonMark = 0,
+    MarkdownDialectGitHub = 0x0004 | 0x0008 | 0x0400 | 0x0100 | 0x0200 | 0x0800 | 0x4000
+};
+enum Feature {
+    FeatureCollapseWhitespace =       0x0001,
+    FeaturePermissiveATXHeaders =     0x0002,
+    FeaturePermissiveURLAutoLinks =   0x0004,
+    FeaturePermissiveMailAutoLinks =  0x0008,
+    FeatureNoIndentedCodeBlocks =     0x0010,
+    FeatureNoHTMLBlocks =             0x0020,
+    FeatureNoHTMLSpans =              0x0040,
+    FeatureTables =                   0x0100,
+    FeatureStrikeThrough =            0x0200,
+    FeaturePermissiveWWWAutoLinks =   0x0400,
+    FeatureTasklists =                0x0800,
+    FeatureUnderline =                0x4000,
+    DialectGitHub =                   MarkdownDialectGitHub
+};