Add decayedType and hasDecayedType AST matchers

[mgehre]

Summary

Add decayedType and hasDecayedType AST matchers

[mgehre]

Add test

[klimek]

lg

[klimek]

Oh, please also run the docs update script

cd docs/tools
python ./dump_ast_matchers.py

include/clang/ASTMatchers/ASTMatchers.h

 /// \code
 ///   template <typename T> struct S {
 ///     void f(S s);
 ///     void g(S<T> s);
 ///   };
 /// \endcode
 AST_TYPE_MATCHER(InjectedClassNameType, injectedClassNameType);
 
+/// \brief Matches decayed type
+/// Example matches i[] in declaration of f.
+///     (matcher = valueDecl(hasType(decayedType(hasDecayedType(pointerType())))))
+/// Example matches i[1].
+///     (matcher = expr(hasType(decayedType(hasDecayedType(pointerType())))))
+/// \code
+///   void f(int i[]) {
+///     i[1] = 0;
+///   }
+/// \endcode
+AST_TYPE_MATCHER(DecayedType, decayedType);
+
+/// \brief Matches the decayed type, whos decayed type matches \c InnerMatcher
+AST_MATCHER_P(DecayedType, hasDecayedType, internal::Matcher<QualType>,
+              InnerType) {
+  return InnerType.matches(Node.getDecayedType(), Finder, Builder);
+}
+
 /// \brief Matches declarations whose declaration context, interpreted as a
 /// Decl, matches \c InnerMatcher.
 ///
 /// Given
 /// \code
 ///   namespace N {
 ///     namespace M {
 ///       class D {};

lib/ASTMatchers/Dynamic/Registry.cpp

RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(cxxRecordDecl);
   REGISTER_MATCHER(cxxReinterpretCastExpr);
   REGISTER_MATCHER(cxxStaticCastExpr);
   REGISTER_MATCHER(cxxTemporaryObjectExpr);
   REGISTER_MATCHER(cxxThisExpr);
   REGISTER_MATCHER(cxxThrowExpr);
   REGISTER_MATCHER(cxxTryStmt);
   REGISTER_MATCHER(cxxUnresolvedConstructExpr);
+  REGISTER_MATCHER(decayedType);
   REGISTER_MATCHER(decl);
   REGISTER_MATCHER(declaratorDecl);
   REGISTER_MATCHER(declCountIs);
   REGISTER_MATCHER(declRefExpr);
   REGISTER_MATCHER(declStmt);
   REGISTER_MATCHER(defaultStmt);
   REGISTER_MATCHER(dependentSizedArrayType);
   REGISTER_MATCHER(doStmt);
RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(hasArgumentOfType);
   REGISTER_MATCHER(hasAttr);
   REGISTER_MATCHER(hasBase);
   REGISTER_MATCHER(hasBody);
   REGISTER_MATCHER(hasCanonicalType);
   REGISTER_MATCHER(hasCaseConstant);
   REGISTER_MATCHER(hasCondition);
   REGISTER_MATCHER(hasConditionVariableStatement);
+  REGISTER_MATCHER(hasDecayedType);
   REGISTER_MATCHER(hasDeclaration);
   REGISTER_MATCHER(hasDeclContext);
   REGISTER_MATCHER(hasDeducedType);
   REGISTER_MATCHER(hasDescendant);
   REGISTER_MATCHER(hasDestinationType);
   REGISTER_MATCHER(hasEitherOperand);
   REGISTER_MATCHER(hasElementType);
   REGISTER_MATCHER(hasElse);