[ASTMatchers] Fixed CastKind being parsed incorrectly for dynamic matchers

[njames93]

Summary

Requires hasCastKind arguments to have CK_ prefixed to bring it in line with the documentation and other matchers that take enumerations.

[njames93]

• Added support for giving suggestions on invalid inputs

[njames93]

Fixed up documentation for CastKind matcher.

[aaron.ballman]

Can you also add some unit tests to the dynamic matcher tests?

[njames93]

Added unit test for matcher

[aaron.ballman]

LGTM!

clang/docs/LibASTMatchersReference.html

 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1CastExpr.html">CastExpr</a>&gt;</td><td class="name" onclick="toggle('hasCastKind0')"><a name="hasCastKind0Anchor">hasCastKind</a></td><td>CastKind Kind</td></tr>
 <tr><td colspan="4" class="doc" id="hasCastKind0"><pre>Matches casts that has a given cast kind.
 
 Example: matches the implicit cast around 0
 (matcher = castExpr(hasCastKind(CK_NullToPointer)))
   int *p = 0;
 
 If the matcher is use from clang-query, CastKind parameter
-should be passed as a quoted string. e.g., ofKind("CK_NullToPointer").
+should be passed as a quoted string. e.g., hasCastKind("CK_NullToPointer").
 </pre></td></tr>
 
 
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1CharacterLiteral.html">CharacterLiteral</a>&gt;</td><td class="name" onclick="toggle('equals4')"><a name="equals4Anchor">equals</a></td><td>bool Value</td></tr>
 <tr><td colspan="4" class="doc" id="equals4"><pre></pre></td></tr>
 
 
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1CharacterLiteral.html">CharacterLiteral</a>&gt;</td><td class="name" onclick="toggle('equals3')"><a name="equals3Anchor">equals</a></td><td>const ValueT  Value</td></tr>

clang/include/clang/ASTMatchers/ASTMatchers.h

 ///
 /// Example: matches the implicit cast around \c 0
 /// (matcher = castExpr(hasCastKind(CK_NullToPointer)))
 /// \code
 ///   int *p = 0;
 /// \endcode
 ///
 /// If the matcher is use from clang-query, CastKind parameter
-/// should be passed as a quoted string. e.g., ofKind("CK_NullToPointer").
+/// should be passed as a quoted string. e.g., hasCastKind("CK_NullToPointer").
 AST_MATCHER_P(CastExpr, hasCastKind, CastKind, Kind) {
   return Node.getCastKind() == Kind;
 }
 
 /// Matches casts whose destination type matches a given matcher.
 ///
 /// (Note: Clang's AST refers to other conversions as "casts" too, and calls
 /// actual casts "explicit" casts.)

clang/lib/ASTMatchers/Dynamic/Marshallers.h

public:
 
   static llvm::Optional<std::string> getBestGuess(const VariantValue &Value);
 };
 
 template <> struct ArgTypeTraits<CastKind> {
 private:
   static Optional<CastKind> getCastKind(llvm::StringRef AttrKind) {
     return llvm::StringSwitch<Optional<CastKind>>(AttrKind)
-#define CAST_OPERATION(Name) .Case( #Name, CK_##Name)
+#define CAST_OPERATION(Name) .Case("CK_" #Name, CK_##Name)
 #include "clang/AST/OperationKinds.def"
         .Default(llvm::None);
   }
 
 public:
   static bool is(const VariantValue &Value) {
     return Value.isString() && getCastKind(Value.getString());
   }

clang/lib/ASTMatchers/Dynamic/Marshallers.cpp

return ::getBestGuess(Value.getString(), llvm::makeArrayRef(Allowed),
                           "attr::");
   return llvm::None;
 }
 
 llvm::Optional<std::string>
 clang::ast_matchers::dynamic::internal::ArgTypeTraits<
     clang::CastKind>::getBestGuess(const VariantValue &Value) {
   static constexpr llvm::StringRef Allowed[] = {
-#define CAST_OPERATION(Name) #Name,
+#define CAST_OPERATION(Name) "CK_" #Name,
 #include "clang/AST/OperationKinds.def"
   };
   if (Value.isString())
-    return ::getBestGuess(Value.getString(), llvm::makeArrayRef(Allowed));
+    return ::getBestGuess(Value.getString(), llvm::makeArrayRef(Allowed),
+                          "CK_");
   return llvm::None;
 }
 
 llvm::Optional<std::string>
 clang::ast_matchers::dynamic::internal::ArgTypeTraits<
     clang::OpenMPClauseKind>::getBestGuess(const VariantValue &Value) {
   static constexpr llvm::StringRef Allowed[] = {
 #define OMP_CLAUSE_CLASS(Enum, Str, Class) #Enum,

clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp

llvm::Optional<DynTypedMatcher> VarDecl(
       Parser::parseMatcherExpression(Code, &Error));
   EXPECT_EQ("", Error.toStringFull());
   Matcher<Decl> M = VarDecl->unconditionalConvertTo<Decl>();
   EXPECT_TRUE(matches("int x = 1 + false;", M));
   EXPECT_FALSE(matches("int x = true + 1;", M));
   EXPECT_FALSE(matches("int x = 1 - false;", M));
   EXPECT_FALSE(matches("int x = true - 1;", M));
 
+  Code = "implicitCastExpr(hasCastKind(\"CK_IntegralToBoolean\"))";
+  llvm::Optional<DynTypedMatcher> implicitIntBooleanCast(
+      Parser::parseMatcherExpression(Code, nullptr, nullptr, &Error));
+  EXPECT_EQ("", Error.toStringFull());
+  Matcher<Stmt> MCastStmt =
+      implicitIntBooleanCast->unconditionalConvertTo<Stmt>();
+  EXPECT_TRUE(matches("bool X = 1;", MCastStmt));
+  EXPECT_FALSE(matches("bool X = true;", MCastStmt));
+
   Code = "functionDecl(hasParameter(1, hasName(\"x\")))";
   llvm::Optional<DynTypedMatcher> HasParameter(
       Parser::parseMatcherExpression(Code, &Error));
   EXPECT_EQ("", Error.toStringFull());
   M = HasParameter->unconditionalConvertTo<Decl>();
 
   EXPECT_TRUE(matches("void f(int a, int x);", M));
   EXPECT_FALSE(matches("void f(int x, int a);", M));