[ASTMatchers] Enhanced support for matchers taking Regex arguments

[njames93]

Summary

Added new Macros AST(_POLYMORPHIC)_MATCHER_REGEX(_OVERLOAD) that define a matchers that take a regular expression string and optionally regular expression flags. This lets users match against nodes while ignoring the case without having to manually use [Aa] or [A-Fa-f] in their regex. The other point this addresses is in the current state, matchers that use regular expressions have to compile them for each node they try to match on, Now the regular expression is compiled once when you define the matcher and used for every node that it tries to match against. If there is an error while compiling the regular expression an error will be logged to stderr showing the bad regex string and the reason it couldn't be compiled. The old behaviour of this was down to the Matcher implementation and some would assert, whereas others just would never match. Support for this has been added to the documentation script as well. Support for this has been added to dynamic matchers ensuring functionality is the same between the 2 use cases.

[njames93]

Include matcher name in error message when failing to build a regex

[njames93]

Moved the code to build and verify the regex out of the macro

[aaron.ballman]

clang/include/clang/ASTMatchers/ASTMatchersInternal.h

1952 ↗

(On Diff #273960)

Is there a reason this needs to be a shared pointer as opposed to a unique pointer that gets moved into the class owning it?

clang/lib/ASTMatchers/Dynamic/Marshallers.cpp

126

This makes me think we want to do a case insensitive comparison rather than an exact case match. Personally, I would always write NewLine as the string literal, but I could easily see someone writing Newline to match the spelling of the RegEx flag and being surprised it doesn't work. WDYT?

clang/lib/ASTMatchers/Dynamic/Marshallers.h

745

I may be misunderstanding this, but it seems suspicious that getNumArgs() returns 0 but getArgKinds() suggests at least one argument. Is that intentional?

770

Are you missing a return here, after issuing the error?

clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp

379

Should we have a failure for something like IgnoreCase | NoFlags ?

[njames93]

clang/include/clang/ASTMatchers/ASTMatchersInternal.h

1952 ↗

(On Diff #273960)

It has to be shared ownership for the polymorphic matchers to enable reuse of PolymorphicMatcherWithParam1. When a matcher or type T is required from a PolymorphicMatcherWithParam1 it creates a copy of the Param. As you can't copy from a unique_ptr, a shared_ptr makes sense.

clang/lib/ASTMatchers/Dynamic/Marshallers.cpp

126

That could work, or I implement the ArgTypeTraits::getBestGuess to handle small issues like that. Would be a little trickier than the other cases as It would need to support |. WDYT?

clang/lib/ASTMatchers/Dynamic/Marshallers.h

745

It was my understanding that when isVariadic() returns true, getNumArgs() is not used. I could change it to return 1, but that wouldn't be any more correct than it is now, nor would it have any functional change.

770

Yes I am

clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp

379

I'm against that, its perfectly legal in non dynamic matchers land to write matchesName("[ABC]*", IgnoreCase | NoFlags) Even if it is a little redundant.

[njames93]

Fix missing return statement

[aaron.ballman]

clang/include/clang/ASTMatchers/ASTMatchersInternal.h

1952 ↗

(On Diff #273960)

Drat, but reasonable, thanks for the explanation.

clang/lib/ASTMatchers/Dynamic/Marshallers.cpp

126

Hmm, I don't have a firm opinion but am slightly leaning towards implementing getBestGuess and using the more strict spellings based purely on personal preference.

clang/lib/ASTMatchers/Dynamic/Marshallers.h

745

Ah, so the real issue is that getNumArgs() is pure virtual, which forces us to ask these sort of silly questions. Good to know, I'm fine with 0, I was just surprised.

clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp

379

Okay, fine by me. I only brought it up because it seems like a very confused user and we have the opportunity to diagnose (due to the dynamic nature here as opposed to the static nature of C++ using bitwise OR directly).

[njames93]

Added best guess support for parsing RegexFlags

[aaron.ballman]

clang/lib/ASTMatchers/Dynamic/Marshallers.cpp

123

const auto & (same below)

157

I would probably simplify this (untested):

SmallVector<StringRef, 4> Split;
llvm::Optional<llvm::Regex::RegexFlags> Flag;

Flags.split(Split, '|', -1, false);
for (StringRef OrFlag : Split) {
  if (llvm::Optional<llvm::Regex::RegexFlags> NextFlag =
            getRegexFlag(OrFlag.trim())) {
    Flag = Flag.getValueOr(llvm::Regex::NoFlags) | *NextFlag;
  }
}
return Flag;

Similar below.

[njames93]

Small refactor based on comments

[njames93]

clang/lib/ASTMatchers/Dynamic/Marshallers.cpp

123

Foiled by my own check ;)

[aaron.ballman]

LGTM!

clang/docs/LibASTMatchersReference.html

 Given
   __attribute__((device)) void f() { ... }
 decl(hasAttr(clang::attr::CUDADevice)) matches the function declaration of
 f. If the matcher is used from clang-query, attr::Kind parameter should be
 passed as a quoted string. e.g., hasAttr("attr::CUDADevice").
 </pre></td></tr>
 
 
-<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('isExpansionInFileMatching0')"><a name="isExpansionInFileMatching0Anchor">isExpansionInFileMatching</a></td><td>std::string RegExp</td></tr>
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('isExpansionInFileMatching0')"><a name="isExpansionInFileMatching0Anchor">isExpansionInFileMatching</a></td><td>StringRef RegExp, Regex::RegexFlags Flags = NoFlags</td></tr>
 <tr><td colspan="4" class="doc" id="isExpansionInFileMatching0"><pre>Matches AST nodes that were expanded within files whose name is
 partially matching a given regex.
 
 Example matches Y but not X
     (matcher = cxxRecordDecl(isExpansionInFileMatching("AST.*"))
   #include "ASTMatcher.h"
   class X {};
 ASTMatcher.h:
   class Y {};
 
 Usable as: Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;, Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;, Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1TypeLoc.html">TypeLoc</a>&gt;
+
+If the matcher is used in clang-query, RegexFlags parameter
+should be passed as a quoted string. e.g: "NoFlags".
+Flags can be combined with '|' example "IgnoreCase | BasicRegex"
 </pre></td></tr>
 
 
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('isExpansionInMainFile0')"><a name="isExpansionInMainFile0Anchor">isExpansionInMainFile</a></td><td></td></tr>
 <tr><td colspan="4" class="doc" id="isExpansionInMainFile0"><pre>Matches AST nodes that were expanded within the main-file.
 
 Example matches X but not Y
   (matcher = cxxRecordDecl(isExpansionInMainFile())

 Example matches X (Name == "X")
   class X;
 
 Example matches X (Name is one of "::a::b::X", "a::b::X", "b::X", "X")
   namespace a { namespace b { class X; } }
 </pre></td></tr>
 
 
-<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1NamedDecl.html">NamedDecl</a>&gt;</td><td class="name" onclick="toggle('matchesName0')"><a name="matchesName0Anchor">matchesName</a></td><td>std::string RegExp</td></tr>
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1NamedDecl.html">NamedDecl</a>&gt;</td><td class="name" onclick="toggle('matchesName0')"><a name="matchesName0Anchor">matchesName</a></td><td>StringRef RegExp, Regex::RegexFlags Flags = NoFlags</td></tr>
 <tr><td colspan="4" class="doc" id="matchesName0"><pre>Matches NamedDecl nodes whose fully qualified names contain
 a substring matched by the given RegExp.
 
 Supports specifying enclosing namespaces or classes by
 prefixing the name with '&lt;enclosing&gt;::'.  Does not match typedefs
 of an underlying type with the given name.
 
 Example matches X (regexp == "::X")
   class X;
 
 Example matches X (regexp is one of "::X", "^foo::.*X", among others)
   namespace foo { namespace bar { class X; } }
+
+If the matcher is used in clang-query, RegexFlags parameter
+should be passed as a quoted string. e.g: "NoFlags".
+Flags can be combined with '|' example "IgnoreCase | BasicRegex"
 </pre></td></tr>
 
 
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1NamespaceDecl.html">NamespaceDecl</a>&gt;</td><td class="name" onclick="toggle('isAnonymous0')"><a name="isAnonymous0Anchor">isAnonymous</a></td><td></td></tr>
 <tr><td colspan="4" class="doc" id="isAnonymous0"><pre>Matches anonymous namespace declarations.
 
 Given
   namespace n {

 matches
   NSString *x = @"hello";
   [x containsString:@"h"];
 but not
   [NSString stringWithFormat:@"format"];
 </pre></td></tr>
 
 
-<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1ObjCMessageExpr.html">ObjCMessageExpr</a>&gt;</td><td class="name" onclick="toggle('matchesSelector0')"><a name="matchesSelector0Anchor">matchesSelector</a></td><td>std::string RegExp</td></tr>
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1ObjCMessageExpr.html">ObjCMessageExpr</a>&gt;</td><td class="name" onclick="toggle('matchesSelector0')"><a name="matchesSelector0Anchor">matchesSelector</a></td><td>StringRef RegExp, Regex::RegexFlags Flags = NoFlags</td></tr>
 <tr><td colspan="4" class="doc" id="matchesSelector0"><pre>Matches ObjC selectors whose name contains
 a substring matched by the given RegExp.
  matcher = objCMessageExpr(matchesSelector("loadHTMLStringmatches the outer message expr in the code below, but NOT the message
  invocation for self.bodyView.
     [self.bodyView loadHTMLString:html baseURL:NULL];
+
+If the matcher is used in clang-query, RegexFlags parameter
+should be passed as a quoted string. e.g: "NoFlags".
+Flags can be combined with '|' example "IgnoreCase | BasicRegex"
 </pre></td></tr>
 
 
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1ObjCMessageExpr.html">ObjCMessageExpr</a>&gt;</td><td class="name" onclick="toggle('numSelectorArgs0')"><a name="numSelectorArgs0Anchor">numSelectorArgs</a></td><td>unsigned N</td></tr>
 <tr><td colspan="4" class="doc" id="numSelectorArgs0"><pre>Matches when the selector has the specified number of arguments
 
  matcher = objCMessageExpr(numSelectorArgs(0));
  matches self.bodyView in the code below

 if different parts of the the statement are expanded from different
 appearances of the macro.
 
 FIXME: Change to be a polymorphic matcher that works on any syntactic
 node. There's nothing `Stmt`-specific about it.
 </pre></td></tr>
 
 
-<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;</td><td class="name" onclick="toggle('isExpansionInFileMatching1')"><a name="isExpansionInFileMatching1Anchor">isExpansionInFileMatching</a></td><td>std::string RegExp</td></tr>
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;</td><td class="name" onclick="toggle('isExpansionInFileMatching1')"><a name="isExpansionInFileMatching1Anchor">isExpansionInFileMatching</a></td><td>StringRef RegExp, Regex::RegexFlags Flags = NoFlags</td></tr>
 <tr><td colspan="4" class="doc" id="isExpansionInFileMatching1"><pre>Matches AST nodes that were expanded within files whose name is
 partially matching a given regex.
 
 Example matches Y but not X
     (matcher = cxxRecordDecl(isExpansionInFileMatching("AST.*"))
   #include "ASTMatcher.h"
   class X {};
 ASTMatcher.h:
   class Y {};
 
 Usable as: Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;, Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;, Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1TypeLoc.html">TypeLoc</a>&gt;
+
+If the matcher is used in clang-query, RegexFlags parameter
+should be passed as a quoted string. e.g: "NoFlags".
+Flags can be combined with '|' example "IgnoreCase | BasicRegex"
 </pre></td></tr>
 
 
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;</td><td class="name" onclick="toggle('isExpansionInMainFile1')"><a name="isExpansionInMainFile1Anchor">isExpansionInMainFile</a></td><td></td></tr>
 <tr><td colspan="4" class="doc" id="isExpansionInMainFile1"><pre>Matches AST nodes that were expanded within the main-file.
 
 Example matches X but not Y
   (matcher = cxxRecordDecl(isExpansionInMainFile())

 Given
   template&lt;typename T&gt; struct C {};
   C&lt;int&gt; c;
 classTemplateSpecializationDecl(templateArgumentCountIs(1))
   matches C&lt;int&gt;.
 </pre></td></tr>
 
 
-<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1TypeLoc.html">TypeLoc</a>&gt;</td><td class="name" onclick="toggle('isExpansionInFileMatching2')"><a name="isExpansionInFileMatching2Anchor">isExpansionInFileMatching</a></td><td>std::string RegExp</td></tr>
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1TypeLoc.html">TypeLoc</a>&gt;</td><td class="name" onclick="toggle('isExpansionInFileMatching2')"><a name="isExpansionInFileMatching2Anchor">isExpansionInFileMatching</a></td><td>StringRef RegExp, Regex::RegexFlags Flags = NoFlags</td></tr>
 <tr><td colspan="4" class="doc" id="isExpansionInFileMatching2"><pre>Matches AST nodes that were expanded within files whose name is
 partially matching a given regex.
 
 Example matches Y but not X
     (matcher = cxxRecordDecl(isExpansionInFileMatching("AST.*"))
   #include "ASTMatcher.h"
   class X {};
 ASTMatcher.h:
   class Y {};
 
 Usable as: Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;, Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;, Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1TypeLoc.html">TypeLoc</a>&gt;
+
+If the matcher is used in clang-query, RegexFlags parameter
+should be passed as a quoted string. e.g: "NoFlags".
+Flags can be combined with '|' example "IgnoreCase | BasicRegex"
 </pre></td></tr>
 
 
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1TypeLoc.html">TypeLoc</a>&gt;</td><td class="name" onclick="toggle('isExpansionInMainFile2')"><a name="isExpansionInMainFile2Anchor">isExpansionInMainFile</a></td><td></td></tr>
 <tr><td colspan="4" class="doc" id="isExpansionInMainFile2"><pre>Matches AST nodes that were expanded within the main-file.
 
 Example matches X but not Y
   (matcher = cxxRecordDecl(isExpansionInMainFile())

clang/docs/tools/dump_ast_matchers.py

if m:
       if n not in ['', '2']:
         raise Exception('Cannot parse "%s"' % declaration)
       args = ', '.join('%s %s' % (args[i], args[i+1])
                        for i in range(0, len(args), 2) if args[i])
       for result_type in result_types:
         add_matcher(result_type, name, args, comment)
       return
 
+    m = re.match(r"""^\s*AST_POLYMORPHIC_MATCHER_REGEX(?:_OVERLOAD)?\(
+                          \s*([^\s,]+)\s*,
+                          \s*AST_POLYMORPHIC_SUPPORTED_TYPES\(([^)]*)\),
+                          \s*([^\s,]+)\s*
+                       (?:,\s*\d+\s*)?
+                      \)\s*{\s*$""", declaration, flags=re.X)
+
+    if m:
+      name, results, arg_name = m.groups()[0:3]
+      result_types = [r.strip() for r in results.split(',')]
+      if allowed_types and allowed_types != result_types:
+        raise Exception('Inconsistent documentation for: %s' % name)
+      arg = "StringRef %s, Regex::RegexFlags Flags = NoFlags" % arg_name
+      comment += """
+If the matcher is used in clang-query, RegexFlags parameter
+should be passed as a quoted string. e.g: "NoFlags".
+Flags can be combined with '|' example \"IgnoreCase | BasicRegex\"
+"""
+      for result_type in result_types:
+        add_matcher(result_type, name, arg, comment)
+      return
+
     m = re.match(r"""^\s*AST_MATCHER_FUNCTION(_P)?(.?)(?:_OVERLOAD)?\(
                        (?:\s*([^\s,]+)\s*,)?
                           \s*([^\s,]+)\s*
                        (?:,\s*([^\s,]+)\s*
                           ,\s*([^\s,]+)\s*)?
                        (?:,\s*([^\s,]+)\s*
                           ,\s*([^\s,]+)\s*)?
                        (?:,\s*\d+\s*)?
if m:
       if n not in ['', '2']:
         raise Exception('Cannot parse "%s"' % declaration)
       args = ', '.join('%s %s' % (args[i], args[i+1])
                        for i in range(0, len(args), 2) if args[i])
       for result_type in result_types:
         add_matcher(result_type, name, args, comment)
       return
 
+    m = re.match(r"""^\s*AST_MATCHER_REGEX(?:_OVERLOAD)?\(
+                       \s*([^\s,]+)\s*,
+                       \s*([^\s,]+)\s*,
+                       \s*([^\s,]+)\s*
+                       (?:,\s*\d+\s*)?
+                      \)\s*{""", declaration, flags=re.X)
+    if m:
+      result, name, arg_name = m.groups()[0:3]
+      if not result:
+        if not allowed_types:
+          raise Exception('Did not find allowed result types for: %s' % name)
+        result_types = allowed_types
+      else:
+        result_types = [result]
+      arg = "StringRef %s, Regex::RegexFlags Flags = NoFlags" % arg_name
+      comment += """
+If the matcher is used in clang-query, RegexFlags parameter
+should be passed as a quoted string. e.g: "NoFlags".
+Flags can be combined with '|' example \"IgnoreCase | BasicRegex\"
+"""
+
+      for result_type in result_types:
+        add_matcher(result_type, name, arg, comment)
+      return
+
     # Parse ArgumentAdapting matchers.
     m = re.match(
         r"""^.*ArgumentAdaptingMatcherFunc<.*>\s*
               ([a-zA-Z]*);$""",
         declaration, flags=re.X)
     if m:
       name = m.groups()[0]
       add_matcher('*', name, 'Matcher<*>', comment)

clang/include/clang/ASTMatchers/ASTMatchers.h

 ///   class X {};
 /// \endcode
 /// ASTMatcher.h:
 /// \code
 ///   class Y {};
 /// \endcode
 ///
 /// Usable as: Matcher<Decl>, Matcher<Stmt>, Matcher<TypeLoc>
-AST_POLYMORPHIC_MATCHER_P(isExpansionInFileMatching,
-                          AST_POLYMORPHIC_SUPPORTED_TYPES(Decl, Stmt, TypeLoc),
-                          std::string, RegExp) {
+AST_POLYMORPHIC_MATCHER_REGEX(isExpansionInFileMatching,
+                              AST_POLYMORPHIC_SUPPORTED_TYPES(Decl, Stmt,
+                                                              TypeLoc),
+                              RegExp) {
   auto &SourceManager = Finder->getASTContext().getSourceManager();
   auto ExpansionLoc = SourceManager.getExpansionLoc(Node.getBeginLoc());
   if (ExpansionLoc.isInvalid()) {
     return false;
   }
   auto FileEntry =
       SourceManager.getFileEntryForID(SourceManager.getFileID(ExpansionLoc));
   if (!FileEntry) {
     return false;
   }
 
   auto Filename = FileEntry->getName();
-  llvm::Regex RE(RegExp);
-  return RE.match(Filename);
+  return RegExp->match(Filename);
 }
 
 /// Matches statements that are (transitively) expanded from the named macro.
 /// Does not match if only part of the statement is expanded from that macro or
 /// if different parts of the the statement are expanded from different
 /// appearances of the macro.
 ///
 /// FIXME: Change to be a polymorphic matcher that works on any syntactic

 /// \code
 ///   class X;
 /// \endcode
 ///
 /// Example matches X (regexp is one of "::X", "^foo::.*X", among others)
 /// \code
 ///   namespace foo { namespace bar { class X; } }
 /// \endcode
-AST_MATCHER_P(NamedDecl, matchesName, std::string, RegExp) {
-  assert(!RegExp.empty());
+AST_MATCHER_REGEX(NamedDecl, matchesName, RegExp) {
   std::string FullNameString = "::" + Node.getQualifiedNameAsString();
-  llvm::Regex RE(RegExp);
-  return RE.match(FullNameString);
+  return RegExp->match(FullNameString);
 }
 
 /// Matches overloaded operator names.
 ///
 /// Matches overloaded operator names specified in strings without the
 /// "operator" prefix: e.g. "<<".
 ///
 /// Given:

 /// Matches ObjC selectors whose name contains
 /// a substring matched by the given RegExp.
 ///  matcher = objCMessageExpr(matchesSelector("loadHTMLString\:baseURL?"));
 ///  matches the outer message expr in the code below, but NOT the message
 ///  invocation for self.bodyView.
 /// \code
 ///     [self.bodyView loadHTMLString:html baseURL:NULL];
 /// \endcode
-AST_MATCHER_P(ObjCMessageExpr, matchesSelector, std::string, RegExp) {
-  assert(!RegExp.empty());
+AST_MATCHER_REGEX(ObjCMessageExpr, matchesSelector, RegExp) {
   std::string SelectorString = Node.getSelector().getAsString();
-  llvm::Regex RE(RegExp);
-  return RE.match(SelectorString);
+  return RegExp->match(SelectorString);
 }
 
 /// Matches when the selector is the empty selector
 ///
 /// Matches only when the selector of the objCMessageExpr is NULL. This may
 /// represent an error condition in the tree!
 AST_MATCHER(ObjCMessageExpr, hasNullSelector) {
   return Node.getSelector().isNull();

clang/include/clang/ASTMatchers/ASTMatchersMacros.h

#define AST_TYPELOC_TRAVERSE_MATCHER(MatcherName, FunctionName, ReturnTypesF)  \
   }                                                                            \
   const ::clang::ast_matchers::internal::TypeTraversePolymorphicMatcher<       \
       TypeLoc,                                                                 \
       ::clang::ast_matchers::internal::TypeLocMatcher##MatcherName##Getter,    \
       ::clang::ast_matchers::internal::TypeLocTraverseMatcher,                 \
       ReturnTypesF>::Func MatcherName##Loc;                                    \
   AST_TYPE_TRAVERSE_MATCHER(MatcherName, FunctionName##Type, ReturnTypesF)
 
+/// AST_MATCHER_REGEX(Type, DefineMatcher, Param) { ... }
+/// defines a function named DefineMatcher() that takes a regular expression
+/// string paramater and an optional RegexFlags parameter and returns a
+/// Matcher<Type> object.
+///
+/// The code between the curly braces has access to the following variables:
+///
+///   Node:                  the AST node being matched; its type is Type.
+///   Param:                 a pointer to an \ref llvm::Regex object
+///   Finder:                an ASTMatchFinder*.
+///   Builder:               a BoundNodesTreeBuilder*.
+///
+/// The code should return true if 'Node' matches.
+#define AST_MATCHER_REGEX(Type, DefineMatcher, Param)                          \
+  AST_MATCHER_REGEX_OVERLOAD(Type, DefineMatcher, Param, 0)
+
+#define AST_MATCHER_REGEX_OVERLOAD(Type, DefineMatcher, Param, OverloadId)     \
+  namespace internal {                                                         \
+  class matcher_##DefineMatcher##OverloadId##Matcher                           \
+      : public ::clang::ast_matchers::internal::MatcherInterface<Type> {       \
+  public:                                                                      \
+    explicit matcher_##DefineMatcher##OverloadId##Matcher(                     \
+        std::shared_ptr<llvm::Regex> RE)                                       \
+        : Param(std::move(RE)) {}                                              \
+    bool matches(const Type &Node,                                             \
+                 ::clang::ast_matchers::internal::ASTMatchFinder *Finder,      \
+                 ::clang::ast_matchers::internal::BoundNodesTreeBuilder        \
+                     *Builder) const override;                                 \
+                                                                               \
+  private:                                                                     \
+    std::shared_ptr<llvm::Regex> const Param;                                  \
+  };                                                                           \
+  }                                                                            \
+  inline ::clang::ast_matchers::internal::Matcher<Type> DefineMatcher(         \
+      llvm::StringRef Param, llvm::Regex::RegexFlags RegexFlags) {             \
+    assert(!Param.empty() && "Empty regex string");                            \
+    auto SharedRegex = std::make_shared<llvm::Regex>(Param, RegexFlags);       \
+    std::string Error;                                                         \
+    if (!SharedRegex->isValid(Error)) {                                        \
+      llvm::errs() << "error: building matcher '" #DefineMatcher "': "         \
+                   << Error << "\nnote: input was '" << Param << "'\n";        \
+    }                                                                          \
+    return ::clang::ast_matchers::internal::makeMatcher(                       \
+        new internal::matcher_##DefineMatcher##OverloadId##Matcher(            \
+            std::move(SharedRegex)));                                          \
+  }                                                                            \
+  inline ::clang::ast_matchers::internal::Matcher<Type> DefineMatcher(         \
+      llvm::StringRef Param) {                                                 \
+    return DefineMatcher(Param, llvm::Regex::NoFlags);                         \
+  }                                                                            \
+                                                                               \
+  typedef ::clang::ast_matchers::internal::Matcher<Type> (                     \
+      &DefineMatcher##_Type##OverloadId##Flags)(llvm::StringRef,               \
+                                                llvm::Regex::RegexFlags);      \
+  typedef ::clang::ast_matchers::internal::Matcher<Type> (                     \
+      &DefineMatcher##_Type##OverloadId)(llvm::StringRef);                     \
+  inline bool internal::matcher_##DefineMatcher##OverloadId##Matcher::matches( \
+      const Type &Node,                                                        \
+      ::clang::ast_matchers::internal::ASTMatchFinder *Finder,                 \
+      ::clang::ast_matchers::internal::BoundNodesTreeBuilder *Builder) const
+
+/// AST_POLYMORPHIC_MATCHER_REGEX(DefineMatcher, ReturnTypesF, Param) { ... }
+/// defines a function named DefineMatcher() that takes a regular expression
+/// string paramater and an optional RegexFlags parameter that is polymorphic in
+/// the return type.
+///
+/// The variables are the same as for
+/// AST_MATCHER_REGEX, with the addition of NodeType, which specifies the node
+/// type of the matcher Matcher<NodeType> returned by the function matcher().
+#define AST_POLYMORPHIC_MATCHER_REGEX(DefineMatcher, ReturnTypesF, Param)      \
+  AST_POLYMORPHIC_MATCHER_REGEX_OVERLOAD(DefineMatcher, ReturnTypesF, Param, 0)
+
+#define AST_POLYMORPHIC_MATCHER_REGEX_OVERLOAD(DefineMatcher, ReturnTypesF,    \
+                                               Param, OverloadId)              \
+  namespace internal {                                                         \
+  template <typename NodeType, typename ParamT>                                \
+  class matcher_##DefineMatcher##OverloadId##Matcher                           \
+      : public ::clang::ast_matchers::internal::MatcherInterface<NodeType> {   \
+  public:                                                                      \
+    explicit matcher_##DefineMatcher##OverloadId##Matcher(                     \
+        std::shared_ptr<llvm::Regex> RE)                                       \
+        : Param(std::move(RE)) {}                                              \
+    bool matches(const NodeType &Node,                                         \
+                 ::clang::ast_matchers::internal::ASTMatchFinder *Finder,      \
+                 ::clang::ast_matchers::internal::BoundNodesTreeBuilder        \
+                     *Builder) const override;                                 \
+                                                                               \
+  private:                                                                     \
+    std::shared_ptr<llvm::Regex> const Param;                                  \
+  };                                                                           \
+  }                                                                            \
+  inline ::clang::ast_matchers::internal::PolymorphicMatcherWithParam1<        \
+      internal::matcher_##DefineMatcher##OverloadId##Matcher,                  \
+      std::shared_ptr<llvm::Regex>, ReturnTypesF>                              \
+  DefineMatcher(llvm::StringRef Param, llvm::Regex::RegexFlags RegexFlags) {   \
+    assert(!Param.empty() && "Empty regex string");                            \
+    auto SharedRegex = std::make_shared<llvm::Regex>(Param, RegexFlags);       \
+    std::string Error;                                                         \
+    if (!SharedRegex->isValid(Error)) {                                        \
+      llvm::errs() << "error: building matcher '" #DefineMatcher "': "         \
+                   << Error << "\nnote: input was '" << Param << "'\n";        \
+    }                                                                          \
+    return ::clang::ast_matchers::internal::PolymorphicMatcherWithParam1<      \
+        internal::matcher_##DefineMatcher##OverloadId##Matcher,                \
+        std::shared_ptr<llvm::Regex>, ReturnTypesF>(std::move(SharedRegex));   \
+  }                                                                            \
+  inline ::clang::ast_matchers::internal::PolymorphicMatcherWithParam1<        \
+      internal::matcher_##DefineMatcher##OverloadId##Matcher,                  \
+      std::shared_ptr<llvm::Regex>, ReturnTypesF>                              \
+  DefineMatcher(llvm::StringRef Param) {                                       \
+    return DefineMatcher(Param, llvm::Regex::NoFlags);                         \
+  }                                                                            \
+  typedef ::clang::ast_matchers::internal::PolymorphicMatcherWithParam1<       \
+      internal::matcher_##DefineMatcher##OverloadId##Matcher,                  \
+      std::shared_ptr<llvm::Regex>, ReturnTypesF> (                            \
+      &DefineMatcher##_Type##OverloadId##Flags)(                               \
+      llvm::StringRef Param, llvm::Regex::RegexFlags RegexFlags);              \
+  typedef ::clang::ast_matchers::internal::PolymorphicMatcherWithParam1<       \
+      internal::matcher_##DefineMatcher##OverloadId##Matcher,                  \
+      std::shared_ptr<llvm::Regex>, ReturnTypesF> (                            \
+      &DefineMatcher##_Type##OverloadId)(llvm::StringRef Param);               \
+  template <typename NodeType, typename ParamT>                                \
+  bool internal::                                                              \
+      matcher_##DefineMatcher##OverloadId##Matcher<NodeType, ParamT>::matches( \
+          const NodeType &Node,                                                \
+          ::clang::ast_matchers::internal::ASTMatchFinder *Finder,             \
+          ::clang::ast_matchers::internal::BoundNodesTreeBuilder *Builder)     \
+          const
+
 #endif // LLVM_CLANG_ASTMATCHERS_ASTMATCHERSMACROS_H

clang/lib/ASTMatchers/Dynamic/Marshallers.h

 #include "clang/Basic/TypeTraits.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/Twine.h"
+#include "llvm/Support/Regex.h"
 #include <cassert>
 #include <cstddef>
 #include <iterator>
 #include <limits>
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
public:
 
   static ArgKind getKind() {
     return ArgKind(ArgKind::AK_String);
   }
 
   static llvm::Optional<std::string> getBestGuess(const VariantValue &Value);
 };
 
+template <> struct ArgTypeTraits<llvm::Regex::RegexFlags> {
+private:
+  static Optional<llvm::Regex::RegexFlags> getFlags(llvm::StringRef Flags);
+
+public:
+  static bool is(const VariantValue &Value) {
+    return Value.isString() && getFlags(Value.getString());
+  }
+
+  static llvm::Regex::RegexFlags get(const VariantValue &Value) {
+    return *getFlags(Value.getString());
+  }
+
+  static ArgKind getKind() { return ArgKind(ArgKind::AK_String); }
+
+  static llvm::Optional<std::string> getBestGuess(const VariantValue &Value) {
+    return llvm::None;
+  }
+};
+
 template <> struct ArgTypeTraits<OpenMPClauseKind> {
 private:
   static Optional<OpenMPClauseKind> getClauseKind(llvm::StringRef ClauseKind) {
     return llvm::StringSwitch<Optional<OpenMPClauseKind>>(ClauseKind)
 #define OMP_CLAUSE_CLASS(Enum, Str, Class) .Case(#Enum, llvm::omp::Clause::Enum)
 #include "llvm/Frontend/OpenMP/OMPKinds.def"
         .Default(llvm::None);
   }
bool isConvertibleTo(ASTNodeKind Kind, unsigned *Specificity,
     }
     return false;
   }
 
 private:
   std::vector<std::unique_ptr<MatcherDescriptor>> Overloads;
 };
 
+template <typename ReturnType>
+class RegexMatcherDescriptor : public MatcherDescriptor {
+public:
+  RegexMatcherDescriptor(ReturnType (*WithFlags)(StringRef,
+                                                 llvm::Regex::RegexFlags),
+                         ReturnType (*NoFlags)(StringRef),
+                         ArrayRef<ASTNodeKind> RetKinds)
+      : WithFlags(WithFlags), NoFlags(NoFlags),
+        RetKinds(RetKinds.begin(), RetKinds.end()) {}
+  bool isVariadic() const override { return true; }
+  unsigned getNumArgs() const override { return 0; }
+
+  void getArgKinds(ASTNodeKind ThisKind, unsigned ArgNo,
+                   std::vector<ArgKind> &Kinds) const override {
+    assert(ArgNo < 2);
+    Kinds.push_back(ArgKind::AK_String);
+  }
+
+  bool isConvertibleTo(ASTNodeKind Kind, unsigned *Specificity,
+                       ASTNodeKind *LeastDerivedKind) const override {
+    return isRetKindConvertibleTo(RetKinds, Kind, Specificity,
+                                  LeastDerivedKind);
+  }
+
+  VariantMatcher create(SourceRange NameRange, ArrayRef<ParserValue> Args,
+                        Diagnostics *Error) const override {
+    if (Args.size() < 1 || Args.size() > 2) {
+      Error->addError(NameRange, Diagnostics::ET_RegistryWrongArgCount)
+          << "1 or 2" << Args.size();
+      return VariantMatcher();
+    }
+    if (!ArgTypeTraits<StringRef>::is(Args[0].Value)) {
+      Error->addError(Args[0].Range, Error->ET_RegistryWrongArgType)
+          << 1 << ArgTypeTraits<StringRef>::getKind().asString()
+          << Args[0].Value.getTypeAsString();
+    }
+    if (Args.size() == 1) {
+      return outvalueToVariantMatcher(
+          NoFlags(ArgTypeTraits<StringRef>::get(Args[0].Value)));
+    }
+    if (!ArgTypeTraits<llvm::Regex::RegexFlags>::is(Args[1].Value)) {
+      Error->addError(Args[1].Range, Error->ET_RegistryWrongArgType)
+          << 2 << ArgTypeTraits<llvm::Regex::RegexFlags>::getKind().asString()
+          << Args[1].Value.getTypeAsString();
+      return VariantMatcher();
+    }
+    return outvalueToVariantMatcher(
+        WithFlags(ArgTypeTraits<StringRef>::get(Args[0].Value),
+                  ArgTypeTraits<llvm::Regex::RegexFlags>::get(Args[1].Value)));
+  }
+
+private:
+  ReturnType (*const WithFlags)(StringRef, llvm::Regex::RegexFlags);
+  ReturnType (*const NoFlags)(StringRef);
+  const std::vector<ASTNodeKind> RetKinds;
+};
+
 /// Variadic operator marshaller function.
 class VariadicOperatorMatcherDescriptor : public MatcherDescriptor {
 public:
   using VarOp = DynTypedMatcher::VariadicOperator;
 
   VariadicOperatorMatcherDescriptor(unsigned MinCount, unsigned MaxCount,
                                     VarOp Op, StringRef MatcherName)
       : MinCount(MinCount), MaxCount(MaxCount), Op(Op),
makeMatcherAutoMarshall(ReturnType (*Func)(ArgType1, ArgType2),
   BuildReturnTypeVector<ReturnType>::build(RetTypes);
   ArgKind AKs[] = { ArgTypeTraits<ArgType1>::getKind(),
                     ArgTypeTraits<ArgType2>::getKind() };
   return std::make_unique<FixedArgCountMatcherDescriptor>(
       matcherMarshall2<ReturnType, ArgType1, ArgType2>,
       reinterpret_cast<void (*)()>(Func), MatcherName, RetTypes, AKs);
 }
 
+template <typename ReturnType>
+std::unique_ptr<MatcherDescriptor> makeMatcherRegexMarshall(
+    ReturnType (*FuncFlags)(llvm::StringRef, llvm::Regex::RegexFlags),
+    ReturnType (*Func)(llvm::StringRef)) {
+  std::vector<ASTNodeKind> RetTypes;
+  BuildReturnTypeVector<ReturnType>::build(RetTypes);
+  return std::make_unique<RegexMatcherDescriptor<ReturnType>>(FuncFlags, Func,
+                                                              RetTypes);
+}
+
 /// Variadic overload.
 template <typename ResultT, typename ArgT,
           ResultT (*Func)(ArrayRef<const ArgT *>)>
 std::unique_ptr<MatcherDescriptor> makeMatcherAutoMarshall(
     ast_matchers::internal::VariadicFunction<ResultT, ArgT, Func> VarFunc,
     StringRef MatcherName) {
   return std::make_unique<VariadicFuncMatcherDescriptor>(VarFunc, MatcherName);
 }

clang/lib/ASTMatchers/Dynamic/Marshallers.cpp

 #define CXX11_UNARY_EXPR_OR_TYPE_TRAIT(Spelling, Name, Key) "UETT_" #Name,
 #include "clang/Basic/TokenKinds.def"
   };
   if (Value.isString())
     return ::getBestGuess(Value.getString(), llvm::makeArrayRef(Allowed),
                           "UETT_");
   return llvm::None;
 }
+
+llvm::Optional<llvm::Regex::RegexFlags>
+clang::ast_matchers::dynamic::internal::ArgTypeTraits<
+    llvm::Regex::RegexFlags>::getFlags(llvm::StringRef Flags) {
+  llvm::Regex::RegexFlags Flag = llvm::Regex::NoFlags;
+  SmallVector<StringRef, 4> Split;
+  Flags.split(Split, '|', -1, false);
+  for (StringRef OrFlag : Split) {
+    OrFlag = OrFlag.trim();
+    if (OrFlag.empty())
+      continue;
+    if (OrFlag == "IgnoreCase")
+      Flag |= llvm::Regex::IgnoreCase;
+    else if (OrFlag == "NewLine")
+      Flag |= llvm::Regex::Newline;
+    else if (OrFlag == "BasicRegex")
+      Flag |= llvm::Regex::BasicRegex;
+    else if (OrFlag == "NoFlags")
+      continue;
+    else
+      return None;
+  }
+  return Flag;
+}

clang/lib/ASTMatchers/Dynamic/Registry.cpp

 #define REGISTER_OVERLOADED_2(name)                                            \
   do {                                                                         \
     std::unique_ptr<MatcherDescriptor> name##Callbacks[] = {                   \
         MATCHER_OVERLOAD_ENTRY(name, 0),                                       \
         MATCHER_OVERLOAD_ENTRY(name, 1)};                                      \
     REGISTER_MATCHER_OVERLOAD(name);                                           \
   } while (false)
 
+#define REGISTER_REGEX_MATCHER(name)                                           \
+  registerMatcher(#name, internal::makeMatcherRegexMarshall(name, name))
+
 /// Generate a registry map with all the known matchers.
 /// Please keep sorted alphabetically!
 RegistryMaps::RegistryMaps() {
   // TODO: Here is the list of the missing matchers, grouped by reason.
   //
   // Polymorphic + argument overload:
   // findAll
   //
RegistryMaps::RegistryMaps() {
 
   std::unique_ptr<MatcherDescriptor> equalsCallbacks[] = {
       MATCHER_OVERLOAD_ENTRY(equals, 0),
       MATCHER_OVERLOAD_ENTRY(equals, 1),
       MATCHER_OVERLOAD_ENTRY(equals, 2),
   };
   REGISTER_MATCHER_OVERLOAD(equals);
 
+  REGISTER_REGEX_MATCHER(isExpansionInFileMatching);
+  REGISTER_REGEX_MATCHER(matchesName);
+  REGISTER_REGEX_MATCHER(matchesSelector);
+
   REGISTER_MATCHER(accessSpecDecl);
   REGISTER_MATCHER(addrLabelExpr);
   REGISTER_MATCHER(alignOfExpr);
   REGISTER_MATCHER(allOf);
   REGISTER_MATCHER(anyOf);
   REGISTER_MATCHER(anything);
   REGISTER_MATCHER(argumentCountIs);
   REGISTER_MATCHER(arraySubscriptExpr);
RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(isDefaultConstructor);
   REGISTER_MATCHER(isDefaulted);
   REGISTER_MATCHER(isDefinition);
   REGISTER_MATCHER(isDelegatingConstructor);
   REGISTER_MATCHER(isDeleted);
   REGISTER_MATCHER(isEnum);
   REGISTER_MATCHER(isExceptionVariable);
   REGISTER_MATCHER(isExpandedFromMacro);
-  REGISTER_MATCHER(isExpansionInFileMatching);
   REGISTER_MATCHER(isExpansionInMainFile);
   REGISTER_MATCHER(isExpansionInSystemHeader);
   REGISTER_MATCHER(isExplicit);
   REGISTER_MATCHER(isExplicitTemplateSpecialization);
   REGISTER_MATCHER(isExpr);
   REGISTER_MATCHER(isExternC);
   REGISTER_MATCHER(isFinal);
   REGISTER_MATCHER(isImplicit);
RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(isVirtualAsWritten);
   REGISTER_MATCHER(isVolatileQualified);
   REGISTER_MATCHER(isWritten);
   REGISTER_MATCHER(lValueReferenceType);
   REGISTER_MATCHER(labelDecl);
   REGISTER_MATCHER(labelStmt);
   REGISTER_MATCHER(lambdaExpr);
   REGISTER_MATCHER(linkageSpecDecl);
-  REGISTER_MATCHER(matchesName);
-  REGISTER_MATCHER(matchesSelector);
   REGISTER_MATCHER(materializeTemporaryExpr);
   REGISTER_MATCHER(member);
   REGISTER_MATCHER(memberExpr);
   REGISTER_MATCHER(memberPointerType);
   REGISTER_MATCHER(namedDecl);
   REGISTER_MATCHER(namesType);
   REGISTER_MATCHER(namespaceAliasDecl);
   REGISTER_MATCHER(namespaceDecl);

clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp

TEST(NameableDeclaration, REMatchesVariousDecls) {
   EXPECT_TRUE(matches("int cabc;", Abc));
 
   DeclarationMatcher StartsWithK = namedDecl(matchesName(":k[^:]*$"));
   EXPECT_TRUE(matches("int k;", StartsWithK));
   EXPECT_TRUE(matches("int kAbc;", StartsWithK));
   EXPECT_TRUE(matches("namespace x { int kTest; }", StartsWithK));
   EXPECT_TRUE(matches("class C { int k; };", StartsWithK));
   EXPECT_TRUE(notMatches("class C { int ckc; };", StartsWithK));
+  EXPECT_TRUE(notMatches("int K;", StartsWithK));
+
+  DeclarationMatcher StartsWithKIgnoreCase =
+      namedDecl(matchesName(":k[^:]*$", llvm::Regex::IgnoreCase));
+  EXPECT_TRUE(matches("int k;", StartsWithKIgnoreCase));
+  EXPECT_TRUE(matches("int K;", StartsWithKIgnoreCase));
 }
 
 TEST(DeclarationMatcher, MatchClass) {
   DeclarationMatcher ClassMatcher(recordDecl());
 
   // This passes on Windows only because we explicitly pass -target
   // i386-unknown-unknown.  If we were to compile with the default target
   // triple, we'd want to EXPECT_TRUE if it's Win32 or MSVC.

clang/unittests/ASTMatchers/Dynamic/ParserTest.cpp

TEST(ParserTest, FullParserTest) {
   Code = "unaryExprOrTypeTraitExpr(ofKind(\"UETT_SizeOf\"))";
   llvm::Optional<DynTypedMatcher> UnaryExprSizeOf(
       Parser::parseMatcherExpression(Code, nullptr, nullptr, &Error));
   EXPECT_EQ("", Error.toStringFull());
   Matcher<Stmt> MStmt = UnaryExprSizeOf->unconditionalConvertTo<Stmt>();
   EXPECT_TRUE(matches("unsigned X = sizeof(int);", MStmt));
   EXPECT_FALSE(matches("unsigned X = alignof(int);", MStmt));
 
+  Code =
+      R"query(namedDecl(matchesName("^::[ABC]*$", "IgnoreCase | BasicRegex")))query";
+  llvm::Optional<DynTypedMatcher> MatchesName(
+      Parser::parseMatcherExpression(Code, nullptr, nullptr, &Error));
+  EXPECT_EQ("", Error.toStringFull());
+  M = MatchesName->unconditionalConvertTo<Decl>();
+  EXPECT_TRUE(matches("unsigned AAACCBB;", M));
+  EXPECT_TRUE(matches("unsigned aaaccbb;", M));
+
   Code = "hasInitializer(\n    binaryOperator(hasLHS(\"A\")))";
   EXPECT_TRUE(!Parser::parseMatcherExpression(Code, &Error).hasValue());
   EXPECT_EQ("1:1: Error parsing argument 1 for matcher hasInitializer.\n"
             "2:5: Error parsing argument 1 for matcher binaryOperator.\n"
             "2:20: Error building matcher hasLHS.\n"
             "2:27: Incorrect type for arg 1. "
             "(Expected = Matcher<Expr>) != (Actual = String)",
             Error.toStringFull());
EXPECT_EQ("1:1: Error parsing argument 1 for matcher decl.\n"
             "1:6: Error building matcher hasAttr.\n"
             "1:14: Unknown value 'Final' for arg 1; did you mean 'attr::Final'",
             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 = "
             "String)",
             ParseMatcherWithError(R"query(decl(hasAttr("unrelated")))query"));
+  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 = "
+            "String)",
+            ParseMatcherWithError(
+                R"query(namedDecl(matchesName("[ABC]*", "Ignorecase")))query"));
+  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 = "
+      "String)",
+      ParseMatcherWithError(
+          R"query(namedDecl(matchesName("[ABC]*", "IgnoreCase & BasicRegex")))query"));
+  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 = "
+      "String)",
+      ParseMatcherWithError(
+          R"query(namedDecl(matchesName("[ABC]*", "IgnoreCase | Basicregex")))query"));
 }
 
 TEST(ParserTest, OverloadErrors) {
   EXPECT_EQ("1:1: Error building matcher callee.\n"
             "1:8: Candidate 1: Incorrect type for arg 1. "
             "(Expected = Matcher<Stmt>) != (Actual = String)\n"
             "1:8: Candidate 2: Incorrect type for arg 1. "
             "(Expected = Matcher<Decl>) != (Actual = String)",

llvm/include/llvm/Support/Regex.h

 // to support backreferences in matches.
 // This implementation also supports matching strings with embedded NUL chars.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_SUPPORT_REGEX_H
 #define LLVM_SUPPORT_REGEX_H
 
+#include "llvm/ADT/BitmaskEnum.h"
 #include <string>
 
 struct llvm_regex;
 
 namespace llvm {
   class StringRef;
   template<typename T> class SmallVectorImpl;
 
   class Regex {
   public:
-    enum {
-      NoFlags=0,
+    enum RegexFlags : unsigned {
+      NoFlags = 0,
       /// Compile for matching that ignores upper/lower case distinctions.
-      IgnoreCase=1,
+      IgnoreCase = 1,
       /// Compile for newline-sensitive matching. With this flag '[^' bracket
       /// expressions and '.' never match newline. A ^ anchor matches the
       /// null string after any newline in the string in addition to its normal
       /// function, and the $ anchor matches the null string before any
       /// newline in the string in addition to its normal function.
-      Newline=2,
+      Newline = 2,
       /// By default, the POSIX extended regular expression (ERE) syntax is
       /// assumed. Pass this flag to turn on basic regular expressions (BRE)
       /// instead.
-      BasicRegex=4
+      BasicRegex = 4,
+
+      LLVM_MARK_AS_BITMASK_ENUM(BasicRegex)
     };
 
     Regex();
     /// Compiles the given regular expression \p Regex.
     ///
     /// \param Regex - referenced string is no longer needed after this
     /// constructor does finish.  Only its compiled form is kept stored.
-    Regex(StringRef Regex, unsigned Flags = NoFlags);
+    Regex(StringRef Regex, RegexFlags Flags = NoFlags);
+    Regex(StringRef Regex, unsigned Flags);
     Regex(const Regex &) = delete;
     Regex &operator=(Regex regex) {
       std::swap(preg, regex.preg);
       std::swap(error, regex.error);
       return *this;
     }
     Regex(Regex &&regex);
     ~Regex();

llvm/lib/Support/Regex.cpp

 // Darwin, if included before any header that (transitively) includes
 // xlocale.h, this will cause trouble, because of missing regex-related types.
 #include "regex_impl.h"
 
 using namespace llvm;
 
 Regex::Regex() : preg(nullptr), error(REG_BADPAT) {}
 
-Regex::Regex(StringRef regex, unsigned Flags) {
+Regex::Regex(StringRef regex, RegexFlags Flags) {
   unsigned flags = 0;
   preg = new llvm_regex();
   preg->re_endp = regex.end();
   if (Flags & IgnoreCase)
     flags |= REG_ICASE;
   if (Flags & Newline)
     flags |= REG_NEWLINE;
   if (!(Flags & BasicRegex))
     flags |= REG_EXTENDED;
   error = llvm_regcomp(preg, regex.data(), flags|REG_PEND);
 }
 
+Regex::Regex(StringRef regex, unsigned Flags)
+    : Regex(regex, static_cast<RegexFlags>(Flags)) {}
+
 Regex::Regex(Regex &&regex) {
   preg = regex.preg;
   error = regex.error;
   regex.preg = nullptr;
   regex.error = REG_BADPAT;
 }
 
 Regex::~Regex() {