Improve dynamic AST matching diagnostics for conversion errors

Currently, when marshaling a dynamic AST matchers, we check for the type
and value validity of matcher arguments at the same time for some matchers.
For instance, when marshaling hasAttr("foo"), the argument is first type
checked to ensure it's a string and then checked to see if that string can
locate an attribute with that name. Similar happens for other enumeration
conversions like cast kinds or unary operator kinds. If the type is
correct but the value cannot be looked up, we make a best-effort attempt
to find a nearby name that the user might have meant, but if one cannot
be found, we throw our hands up and claim the types don't match.

This has an unfortunate behavior that when the user enters something of
the correct type but a best guess cannot be located, you get confusing
error messages like:
Incorrect type for arg 1. (Expected = string) != (Actual = String).

This patch splits the argument check into two parts: if the types don't
match, give a type diagnostic. If the type matches but the value cannot
be converted, give a best guess diagnostic or a value could not be
located diagnostic. This addresses PR47057.

clang/lib/ASTMatchers/Dynamic/Marshallers.h

@@ -58,7 +58,10 @@ template <class T> struct ArgTypeTraits<const T &> : public ArgTypeTraits<T> {
 };
 
 template <> struct ArgTypeTraits<std::string> {
-  static bool is(const VariantValue &Value) { return Value.isString(); }
+  static bool hasCorrectType(const VariantValue &Value) {
+    return Value.isString();
+  }
+  static bool hasCorrectValue(const VariantValue &Value) { return true; }
 
   static const std::string &get(const VariantValue &Value) {
     return Value.getString();
@@ -78,8 +81,11 @@ struct ArgTypeTraits<StringRef> : public ArgTypeTraits<std::string> {
 };
 
 template <class T> struct ArgTypeTraits<ast_matchers::internal::Matcher<T>> {
-  static bool is(const VariantValue &Value) {
+  static bool hasCorrectType(const VariantValue& Value) {
-    return Value.isMatcher() && Value.getMatcher().hasTypedMatcher<T>();
+    return Value.isMatcher();
+  }
+  static bool hasCorrectValue(const VariantValue &Value) {
+    return Value.getMatcher().hasTypedMatcher<T>();
   }
 
   static ast_matchers::internal::Matcher<T> get(const VariantValue &Value) {
@@ -96,7 +102,10 @@ template <class T> struct ArgTypeTraits<ast_matchers::internal::Matcher<T>> {
 };
 
 template <> struct ArgTypeTraits<bool> {
-  static bool is(const VariantValue &Value) { return Value.isBoolean(); }
+  static bool hasCorrectType(const VariantValue &Value) {
+    return Value.isBoolean();
+  }
+  static bool hasCorrectValue(const VariantValue &Value) { return true; }
 
   static bool get(const VariantValue &Value) {
     return Value.getBoolean();
@@ -112,7 +121,10 @@ template <> struct ArgTypeTraits<bool> {
 };
 
 template <> struct ArgTypeTraits<double> {
-  static bool is(const VariantValue &Value) { return Value.isDouble(); }
+  static bool hasCorrectType(const VariantValue &Value) {
+    return Value.isDouble();
+  }
+  static bool hasCorrectValue(const VariantValue &Value) { return true; }
 
   static double get(const VariantValue &Value) {
     return Value.getDouble();
@@ -128,7 +140,10 @@ template <> struct ArgTypeTraits<double> {
 };
 
 template <> struct ArgTypeTraits<unsigned> {
-  static bool is(const VariantValue &Value) { return Value.isUnsigned(); }
+  static bool hasCorrectType(const VariantValue &Value) {
+    return Value.isUnsigned();
+  }
+  static bool hasCorrectValue(const VariantValue &Value) { return true; }
 
   static unsigned get(const VariantValue &Value) {
     return Value.getUnsigned();
@@ -153,8 +168,11 @@ private:
   }
 
 public:
-  static bool is(const VariantValue &Value) {
+  static bool hasCorrectType(const VariantValue &Value) {
-    return Value.isString() && getAttrKind(Value.getString());
+    return Value.isString();
+  }
+  static bool hasCorrectValue(const VariantValue& Value) {
+    return getAttrKind(Value.getString()).hasValue();
   }
 
   static attr::Kind get(const VariantValue &Value) {
@@ -178,8 +196,11 @@ private:
   }
 
 public:
-  static bool is(const VariantValue &Value) {
+  static bool hasCorrectType(const VariantValue &Value) {
-    return Value.isString() && getCastKind(Value.getString());
+    return Value.isString();
+  }
+  static bool hasCorrectValue(const VariantValue& Value) {
+    return getCastKind(Value.getString()).hasValue();
   }
 
   static CastKind get(const VariantValue &Value) {
@@ -198,8 +219,11 @@ private:
   static Optional<llvm::Regex::RegexFlags> getFlags(llvm::StringRef Flags);
 
 public:
-  static bool is(const VariantValue &Value) {
+  static bool hasCorrectType(const VariantValue &Value) {
-    return Value.isString() && getFlags(Value.getString());
+    return Value.isString();
+  }
+  static bool hasCorrectValue(const VariantValue& Value) {
+    return getFlags(Value.getString()).hasValue();
   }
 
   static llvm::Regex::RegexFlags get(const VariantValue &Value) {
@@ -221,8 +245,11 @@ private:
   }
 
 public:
-  static bool is(const VariantValue &Value) {
+  static bool hasCorrectType(const VariantValue &Value) {
-    return Value.isString() && getClauseKind(Value.getString());
+    return Value.isString();
+  }
+  static bool hasCorrectValue(const VariantValue& Value) {
+    return getClauseKind(Value.getString()).hasValue();
   }
 
   static OpenMPClauseKind get(const VariantValue &Value) {
@@ -248,8 +275,11 @@ private:
   }
 
 public:
-  static bool is(const VariantValue &Value) {
+  static bool hasCorrectType(const VariantValue &Value) {
-    return Value.isString() && getUnaryOrTypeTraitKind(Value.getString());
+    return Value.isString();
+  }
+  static bool hasCorrectValue(const VariantValue& Value) {
+    return getUnaryOrTypeTraitKind(Value.getString()).hasValue();
   }
 
   static UnaryExprOrTypeTrait get(const VariantValue &Value) {
@@ -453,12 +483,31 @@ variadicMatcherDescriptor(StringRef MatcherName, SourceRange NameRange,
 
     const ParserValue &Arg = Args[i];
     const VariantValue &Value = Arg.Value;
-    if (!ArgTraits::is(Value)) {
+    if (!ArgTraits::hasCorrectType(Value)) {
       Error->addError(Arg.Range, Error->ET_RegistryWrongArgType)
           << (i + 1) << ArgTraits::getKind().asString() << Value.getTypeAsString();
       HasError = true;
       break;
     }
+    if (!ArgTraits::hasCorrectValue(Value)) {
+      if (llvm::Optional<std::string> BestGuess =
+              ArgTraits::getBestGuess(Value)) {
+        Error->addError(Arg.Range, Error->ET_RegistryUnknownEnumWithReplace)
+            << i + 1 << Value.getString() << *BestGuess;
+      } else if (Value.isString()) {
+        Error->addError(Arg.Range, Error->ET_RegistryValueNotFound)
+            << Value.getString();
+      } else {
+        // This isn't ideal, but it's better than reporting an empty string as
+        // the error in this case.
+        Error->addError(Arg.Range, Error->ET_RegistryWrongArgType)
+            << (i + 1) << ArgTraits::getKind().asString()
+            << Value.getTypeAsString();
+      }
+      HasError = true;
+      break;
+    }
+
     InnerArgs[i] = new ArgT(ArgTraits::get(Value));
   }
 
@@ -568,16 +617,21 @@ private:
   }
 
 #define CHECK_ARG_TYPE(index, type)                                            \
-  if (!ArgTypeTraits<type>::is(Args[index].Value)) {                           \
+  if (!ArgTypeTraits<type>::hasCorrectType(Args[index].Value)) {               \
+    Error->addError(Args[index].Range, Error->ET_RegistryWrongArgType)         \
+        << (index + 1) << ArgTypeTraits<type>::getKind().asString()            \
+        << Args[index].Value.getTypeAsString();                                \
+    return VariantMatcher();                                                   \
+  }                                                                            \
+  if (!ArgTypeTraits<type>::hasCorrectValue(Args[index].Value)) {              \
     if (llvm::Optional<std::string> BestGuess =                                \
             ArgTypeTraits<type>::getBestGuess(Args[index].Value)) {            \
       Error->addError(Args[index].Range,                                       \
                       Error->ET_RegistryUnknownEnumWithReplace)                \
           << index + 1 << Args[index].Value.getString() << *BestGuess;         \
-    } else {                                                                   \
+    } else if (Args[index].Value.isString()) {                                 \
-      Error->addError(Args[index].Range, Error->ET_RegistryWrongArgType)       \
+      Error->addError(Args[index].Range, Error->ET_RegistryValueNotFound)      \
-          << (index + 1) << ArgTypeTraits<type>::getKind().asString()          \
+          << Args[index].Value.getString();                                    \
-          << Args[index].Value.getTypeAsString();                              \
     }                                                                          \
     return VariantMatcher();                                                   \
   }
@@ -761,7 +815,7 @@ public:
           << "1 or 2" << Args.size();
       return VariantMatcher();
     }
-    if (!ArgTypeTraits<StringRef>::is(Args[0].Value)) {
+    if (!ArgTypeTraits<StringRef>::hasCorrectType(Args[0].Value)) {
       Error->addError(Args[0].Range, Error->ET_RegistryWrongArgType)
           << 1 << ArgTypeTraits<StringRef>::getKind().asString()
           << Args[0].Value.getTypeAsString();
@@ -771,16 +825,23 @@ public:
       return outvalueToVariantMatcher(
           NoFlags(ArgTypeTraits<StringRef>::get(Args[0].Value)));
     }
-    if (!ArgTypeTraits<llvm::Regex::RegexFlags>::is(Args[1].Value)) {
+    if (!ArgTypeTraits<llvm::Regex::RegexFlags>::hasCorrectType(
+            Args[1].Value)) {
+      Error->addError(Args[1].Range, Error->ET_RegistryWrongArgType)
+          << 2 << ArgTypeTraits<llvm::Regex::RegexFlags>::getKind().asString()
+          << Args[1].Value.getTypeAsString();
+      return VariantMatcher();
+    }
+    if (!ArgTypeTraits<llvm::Regex::RegexFlags>::hasCorrectValue(
+            Args[1].Value)) {
       if (llvm::Optional<std::string> BestGuess =
               ArgTypeTraits<llvm::Regex::RegexFlags>::getBestGuess(
                   Args[1].Value)) {
         Error->addError(Args[1].Range, Error->ET_RegistryUnknownEnumWithReplace)
             << 2 << Args[1].Value.getString() << *BestGuess;
       } else {
-        Error->addError(Args[1].Range, Error->ET_RegistryWrongArgType)
+        Error->addError(Args[1].Range, Error->ET_RegistryValueNotFound)
-            << 2 << ArgTypeTraits<llvm::Regex::RegexFlags>::getKind().asString()
+            << Args[1].Value.getString();
-            << Args[1].Value.getTypeAsString();
       }
       return VariantMatcher();
     }

clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp

@@ -354,8 +354,7 @@ TEST(ParserTest, Errors) {
             ParseMatcherWithError(R"query(decl(hasAttr("Final")))query"));
   EXPECT_EQ("1:1: Error parsing argument 1 for matcher decl.\n"
             "1:6: Error building matcher hasAttr.\n"
-            "1:14: Incorrect type for arg 1. (Expected = string) != (Actual = "
+            "1:14: Value not found: unrelated",
-            "String)",
             ParseMatcherWithError(R"query(decl(hasAttr("unrelated")))query"));
   EXPECT_EQ(
       "1:1: Error parsing argument 1 for matcher namedDecl.\n"
@@ -366,8 +365,7 @@ TEST(ParserTest, Errors) {
   EXPECT_EQ(
       "1:1: Error parsing argument 1 for matcher namedDecl.\n"
       "1:11: Error building matcher matchesName.\n"
-      "1:33: Incorrect type for arg 2. (Expected = string) != (Actual = "
+      "1:33: Value not found: IgnoreCase & BasicRegex",
-      "String)",
       ParseMatcherWithError(
           R"query(namedDecl(matchesName("[ABC]*", "IgnoreCase & BasicRegex")))query"));
   EXPECT_EQ(