[clang][NFC] Use enum for -fstrict-flex-arrays

Use enums for the strict flex arrays flag so that it's more readable.

Differential Revision: https://reviews.llvm.org/D135107

clang/include/clang/AST/Expr.h

@@ -528,7 +528,8 @@ public:
   /// When IgnoreTemplateOrMacroSubstitution is set, it doesn't consider sizes
   /// resulting from the substitution of a macro or a template as special sizes.
   bool isFlexibleArrayMemberLike(
-      ASTContext &Context, unsigned StrictFlexArraysLevel,
+      ASTContext &Context,
+      LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel,
       bool IgnoreTemplateOrMacroSubstitution = false) const;
 
   /// isIntegerConstantExpr - Return the value if this expression is a valid

clang/include/clang/Basic/LangOptions.def

@@ -427,7 +427,10 @@ LANGOPT(PaddingOnUnsignedFixedPoint, 1, 0,
 LANGOPT(RegisterStaticDestructors, 1, 1, "Register C++ static destructors")
 
 LANGOPT(MatrixTypes, 1, 0, "Enable or disable the builtin matrix type")
-LANGOPT(StrictFlexArrays, 2, 0, "Rely on strict definition of flexible arrays")
+
+ENUM_LANGOPT(StrictFlexArraysLevel, StrictFlexArraysLevelKind, 2,
+             StrictFlexArraysLevelKind::Default,
+             "Rely on strict definition of flexible arrays")
 
 COMPATIBLE_VALUE_LANGOPT(MaxTokens, 32, 0, "Max number of tokens per TU or 0")
 

clang/include/clang/Basic/LangOptions.h

@@ -365,6 +365,17 @@ public:
     All,
   };
 
+  enum class StrictFlexArraysLevelKind {
+    /// Any trailing array member is a FAM.
+    Default = 0,
+    /// Any trailing array member of undefined, 0, or 1 size is a FAM.
+    OneZeroOrIncomplete = 1,
+    /// Any trailing array member of undefined or 0 size is a FAM.
+    ZeroOrIncomplete = 2,
+    /// Any trailing array member of undefined size is a FAM.
+    Incomplete = 3,
+  };
+
 public:
   /// The used language standard.
   LangStandard::Kind LangStd;

clang/include/clang/Driver/Options.td

@@ -1149,10 +1149,12 @@ def fapple_kext : Flag<["-"], "fapple-kext">, Group<f_Group>, Flags<[CC1Option]>
   MarshallingInfoFlag<LangOpts<"AppleKext">>;
 def fstrict_flex_arrays_EQ : Joined<["-"], "fstrict-flex-arrays=">, Group<f_Group>,
   MetaVarName<"<n>">, Values<"0,1,2">,
-  LangOpts<"StrictFlexArrays">,
+  LangOpts<"StrictFlexArraysLevel">,
   Flags<[CC1Option]>,
+  NormalizedValuesScope<"LangOptions::StrictFlexArraysLevelKind">,
+  NormalizedValues<["Default", "OneZeroOrIncomplete", "ZeroOrIncomplete", "Incomplete"]>,
   HelpText<"Enable optimizations based on the strict definition of flexible arrays">,
-  MarshallingInfoInt<LangOpts<"StrictFlexArrays">>;
+  MarshallingInfoEnum<LangOpts<"StrictFlexArraysLevel">, "Default">;
 defm apple_pragma_pack : BoolFOption<"apple-pragma-pack",
   LangOpts<"ApplePragmaPack">, DefaultFalse,
   PosFlag<SetTrue, [CC1Option], "Enable Apple gcc-compatible #pragma pack handling">,

clang/lib/AST/Expr.cpp

@@ -204,7 +204,8 @@ bool Expr::isKnownToHaveBooleanValue(bool Semantic) const {
 }
 
 bool Expr::isFlexibleArrayMemberLike(
-    ASTContext &Context, unsigned StrictFlexArraysLevel,
+    ASTContext &Context,
+    LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel,
     bool IgnoreTemplateOrMacroSubstitution) const {
 
   // For compatibility with existing code, we treat arrays of length 0 or
@@ -219,7 +220,8 @@ bool Expr::isFlexibleArrayMemberLike(
     // FIXME: While the default -fstrict-flex-arrays=0 permits Size>1 trailing
     // arrays to be treated as flexible-array-members, we still emit diagnostics
     // as if they are not. Pending further discussion...
-    if (StrictFlexArraysLevel >= 2 || Size.uge(2))
+    using FAMKind = LangOptions::StrictFlexArraysLevelKind;
+    if (StrictFlexArraysLevel == FAMKind::ZeroOrIncomplete || Size.uge(2))
       return false;
 
   } else if (!Context.getAsIncompleteArrayType(getType()))

clang/lib/AST/ExprConstant.cpp

@@ -11613,15 +11613,17 @@ static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) {
   //   conservative with the last element in structs (if it's an array), so our
   //   current behavior is more compatible than an explicit list approach would
   //   be.
-  int StrictFlexArraysLevel = Ctx.getLangOpts().StrictFlexArrays;
+  using FAMKind = LangOptions::StrictFlexArraysLevelKind;
+  FAMKind StrictFlexArraysLevel = Ctx.getLangOpts().getStrictFlexArraysLevel();
   return LVal.InvalidBase &&
          Designator.Entries.size() == Designator.MostDerivedPathLength &&
          Designator.MostDerivedIsArrayElement &&
          (Designator.isMostDerivedAnUnsizedArray() ||
           Designator.getMostDerivedArraySize() == 0 ||
           (Designator.getMostDerivedArraySize() == 1 &&
-           StrictFlexArraysLevel < 2) ||
-          StrictFlexArraysLevel == 0) &&
+           StrictFlexArraysLevel != FAMKind::Incomplete &&
+           StrictFlexArraysLevel != FAMKind::ZeroOrIncomplete) ||
+          StrictFlexArraysLevel == FAMKind::Default) &&
          isDesignatorAtObjectEnd(Ctx, LVal);
 }
 

clang/lib/CodeGen/CGExpr.cpp

@@ -919,7 +919,8 @@ llvm::Value *CodeGenFunction::LoadPassedObjectSize(const Expr *E,
 static llvm::Value *getArrayIndexingBound(CodeGenFunction &CGF,
                                           const Expr *Base,
                                           QualType &IndexedType,
-                                          unsigned StrictFlexArraysLevel) {
+                                          LangOptions::StrictFlexArraysLevelKind
+                                          StrictFlexArraysLevel) {
   // For the vector indexing extension, the bound is the number of elements.
   if (const VectorType *VT = Base->getType()->getAs<VectorType>()) {
     IndexedType = Base->getType();
@@ -958,7 +959,8 @@ void CodeGenFunction::EmitBoundsCheck(const Expr *E, const Expr *Base,
          "should not be called unless adding bounds checks");
   SanitizerScope SanScope(this);
 
-  const unsigned StrictFlexArraysLevel = getLangOpts().StrictFlexArrays;
+  const LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel =
+    getLangOpts().getStrictFlexArraysLevel();
 
   QualType IndexedType;
   llvm::Value *Bound =

clang/lib/Sema/SemaChecking.cpp

@@ -15915,7 +15915,8 @@ void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
   const ConstantArrayType *ArrayTy =
       Context.getAsConstantArrayType(BaseExpr->getType());
 
-  unsigned StrictFlexArraysLevel = getLangOpts().StrictFlexArrays;
+  LangOptions::StrictFlexArraysLevelKind
+    StrictFlexArraysLevel = getLangOpts().getStrictFlexArraysLevel();
 
   const Type *BaseType =
       ArrayTy == nullptr ? nullptr : ArrayTy->getElementType().getTypePtr();

clang/lib/StaticAnalyzer/Core/MemRegion.cpp

@@ -794,7 +794,11 @@ DefinedOrUnknownSVal MemRegionManager::getStaticSize(const MemRegion *MR,
         if (Size.isZero())
           return true;
 
-        if (getContext().getLangOpts().StrictFlexArrays >= 2)
+        using FAMKind = LangOptions::StrictFlexArraysLevelKind;
+        const FAMKind StrictFlexArraysLevel =
+          Ctx.getLangOpts().getStrictFlexArraysLevel();
+        if (StrictFlexArraysLevel == FAMKind::ZeroOrIncomplete ||
+            StrictFlexArraysLevel == FAMKind::Incomplete)
           return false;
 
         const AnalyzerOptions &Opts = SVB.getAnalyzerOptions();