[clang][docs] Add documentation for APValue constructors (#109994)

I always get confused when looking at these.

Author: tbaederr

clang/include/clang/AST/APValue.h

@@ -314,51 +314,95 @@ class APValue {
   DataType Data;
 
 public:
+  /// Creates an empty APValue of type None.
   APValue() : Kind(None) {}
+  /// Creates an integer APValue holding the given value.
   explicit APValue(APSInt I) : Kind(None) {
     MakeInt(); setInt(std::move(I));
   }
+  /// Creates a float APValue holding the given value.
   explicit APValue(APFloat F) : Kind(None) {
     MakeFloat(); setFloat(std::move(F));
   }
+  /// Creates a fixed-point APValue holding the given value.
   explicit APValue(APFixedPoint FX) : Kind(None) {
     MakeFixedPoint(std::move(FX));
   }
+  /// Creates a vector APValue with \p N elements. The elements
+  /// are read from \p E.
   explicit APValue(const APValue *E, unsigned N) : Kind(None) {
     MakeVector(); setVector(E, N);
   }
+  /// Creates an integer complex APValue with the given real and imaginary
+  /// values.
   APValue(APSInt R, APSInt I) : Kind(None) {
     MakeComplexInt(); setComplexInt(std::move(R), std::move(I));
   }
+  /// Creates a float complex APValue with the given real and imaginary values.
   APValue(APFloat R, APFloat I) : Kind(None) {
     MakeComplexFloat(); setComplexFloat(std::move(R), std::move(I));
   }
   APValue(const APValue &RHS);
   APValue(APValue &&RHS);
-  APValue(LValueBase B, const CharUnits &O, NoLValuePath N,
+  /// Creates an lvalue APValue without an lvalue path.
+  /// \param Base The base of the lvalue.
+  /// \param Offset The offset of the lvalue.
+  /// \param IsNullPtr Whether this lvalue is a null pointer.
+  APValue(LValueBase Base, const CharUnits &Offset, NoLValuePath,
           bool IsNullPtr = false)
       : Kind(None) {
-    MakeLValue(); setLValue(B, O, N, IsNullPtr);
-  }
-  APValue(LValueBase B, const CharUnits &O, ArrayRef<LValuePathEntry> Path,
-          bool OnePastTheEnd, bool IsNullPtr = false)
+    MakeLValue();
+    setLValue(Base, Offset, NoLValuePath{}, IsNullPtr);
+  }
+  /// Creates an lvalue APValue with an lvalue path.
+  /// \param Base The base of the lvalue.
+  /// \param Offset The offset of the lvalue.
+  /// \param Path The lvalue path.
+  /// \param OnePastTheEnd Whether this lvalue is one-past-the-end of the
+  /// subobject it points to.
+  /// \param IsNullPtr Whether this lvalue is a null pointer.
+  APValue(LValueBase Base, const CharUnits &Offset,
+          ArrayRef<LValuePathEntry> Path, bool OnePastTheEnd,
+          bool IsNullPtr = false)
       : Kind(None) {
-    MakeLValue(); setLValue(B, O, Path, OnePastTheEnd, IsNullPtr);
-  }
+    MakeLValue();
+    setLValue(Base, Offset, Path, OnePastTheEnd, IsNullPtr);
+  }
+  /// Creates a new array APValue.
+  /// \param UninitArray Marker. Pass an empty UninitArray.
+  /// \param InitElts Number of elements you're going to initialize in the
+  /// array.
+  /// \param Size Full size of the array.
   APValue(UninitArray, unsigned InitElts, unsigned Size) : Kind(None) {
     MakeArray(InitElts, Size);
   }
-  APValue(UninitStruct, unsigned B, unsigned M) : Kind(None) {
-    MakeStruct(B, M);
-  }
-  explicit APValue(const FieldDecl *D, const APValue &V = APValue())
+  /// Creates a new struct APValue.
+  /// \param UninitStruct Marker. Pass an empty UninitStruct.
+  /// \param NumBases Number of bases.
+  /// \param NumMembers Number of members.
+  APValue(UninitStruct, unsigned NumBases, unsigned NumMembers) : Kind(None) {
+    MakeStruct(NumBases, NumMembers);
+  }
+  /// Creates a new union APValue.
+  /// \param ActiveDecl The FieldDecl of the active union member.
+  /// \param ActiveValue The value of the active union member.
+  explicit APValue(const FieldDecl *ActiveDecl,
+                   const APValue &ActiveValue = APValue())
       : Kind(None) {
-    MakeUnion(); setUnion(D, V);
+    MakeUnion();
+    setUnion(ActiveDecl, ActiveValue);
   }
+  /// Creates a new member pointer APValue.
+  /// \param Member Declaration of the member
+  /// \param IsDerivedMember Whether member is a derived one.
+  /// \param Path The path of the member.
   APValue(const ValueDecl *Member, bool IsDerivedMember,
           ArrayRef<const CXXRecordDecl*> Path) : Kind(None) {
     MakeMemberPointer(Member, IsDerivedMember, Path);
   }
+  /// Creates a new address label diff APValue.
+  /// \param LHSExpr The left-hand side of the difference.
+  /// \param RHSExpr The right-hand side of the difference.
   APValue(const AddrLabelExpr* LHSExpr, const AddrLabelExpr* RHSExpr)
       : Kind(None) {
     MakeAddrLabelDiff(); setAddrLabelDiff(LHSExpr, RHSExpr);