[PATCH] AST traversal from types to decls

[aaron.ballman]

Summary

The AST matching code that traverses from types to decls misses a lot of possible conversions. This patch adds all of the conversions I could find. However, not all of the type->decl conversions can be used from the AST matchers yet. For instance, we do not have matcher support for ObjCInterfaceDecl. I've added a test case for the one conversion we currently support. I feel it's reasonable to have reduced test coverage for the other types at this point compared to the difficulty of tracking down why simple matchers were failing.

This now allows us to write a matcher like:

varDecl(hasType(namedDecl(hasName("Foo"))))

that matches code like:

typedef int Foo;
Foo f; // matches f

Previously, the hasType(namedDecl()) matcher would only properly match if the type queried was a TagType. Now it can support any type which is traversable to a decl.

[aaron.ballman]

After speaking with Manuel on IRC about the testability, we decided the best approach would be to add the AST matcher functionality required to actually test out the changes to HasDeclarationMatcher::matchesSpecialized(). I've updated the patch accordingly. Specifically, this new patch:

• Fixed HasDeclarationMatcher to properly convert all types into decls where possible
• Added objcObjectPointerType()
• Updated documentation for pointerType() to call out that it does not match ObjCObjectPointerType types
• Added objcInterfaceDecl()
• Changed pointsTo() to handle ObjCObjectPointerType as well as PointerType
• Added templateTypeParmType()
• Added injectedClassNameType()
• Added unresolvedUsingTypenameDecl()
• Added tests and documentation for everything

While this may seem like a lot of unrelated changes, they all relate back to fixing HasDeclarationMatcher.

[klimek]

LG. This is great, thanks!

[aaron.ballman]

Thanks! I've commit in r247404.

docs/LibASTMatchersReference.html

 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('objcInterfaceDecl0')"><a name="objcInterfaceDecl0Anchor">objcInterfaceDecl</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1ObjCInterfaceDecl.html">ObjCInterfaceDecl</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="objcInterfaceDecl0"><pre>Matches Objective-C interface declarations.
+
+Example matches Foo
+  @interface Foo
+  @end
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('parmVarDecl0')"><a name="parmVarDecl0Anchor">parmVarDecl</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1ParmVarDecl.html">ParmVarDecl</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="parmVarDecl0"><pre>Matches parameter variable declarations.
 

 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('unresolvedUsingTypenameDecl0')"><a name="unresolvedUsingTypenameDecl0Anchor">unresolvedUsingTypenameDecl</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1UnresolvedUsingTypenameDecl.html">UnresolvedUsingTypenameDecl</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="unresolvedUsingTypenameDecl0"><pre>Matches unresolved using value declarations that involve the
+typename.
+
+Given
+  template &lt;typename T&gt;
+  struct Base { typedef T Foo; };
+
+  template&lt;typename T&gt;
+  struct S : private Base&lt;T&gt; {
+    using typename Base&lt;T&gt;::Foo;
+  };
+unresolvedUsingTypenameDecl()
+  matches using Base&lt;T&gt;::Foo </pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('unresolvedUsingValueDecl0')"><a name="unresolvedUsingValueDecl0Anchor">unresolvedUsingValueDecl</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1UnresolvedUsingValueDecl.html">UnresolvedUsingValueDecl</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="unresolvedUsingValueDecl0"><pre>Matches unresolved using value declarations.
 

 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>&gt;</td><td class="name" onclick="toggle('injectedClassNameType0')"><a name="injectedClassNameType0Anchor">injectedClassNameType</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1InjectedClassNameType.html">InjectedClassNameType</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="injectedClassNameType0"><pre>Matches injected class name types.
+
+Example matches S s, but not S&lt;T&gt; s.
+    (matcher = parmVarDecl(hasType(injectedClassNameType())))
+  template &lt;typename T&gt; struct S {
+    void f(S s);
+    void g(S&lt;T&gt; s);
+  };
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>&gt;</td><td class="name" onclick="toggle('lValueReferenceType0')"><a name="lValueReferenceType0Anchor">lValueReferenceType</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1LValueReferenceType.html">LValueReferenceType</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="lValueReferenceType0"><pre>Matches lvalue reference types.
 

 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>&gt;</td><td class="name" onclick="toggle('objcObjectPointerType0')"><a name="objcObjectPointerType0Anchor">objcObjectPointerType</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1ObjCObjectPointerType.html">ObjCObjectPointerType</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="objcObjectPointerType0"><pre>Matches an Objective-C object pointer type, which is different from
+a pointer type, despite being syntactically similar.
+
+Given
+  int *a;
+
+  @interface Foo
+  @end
+  Foo *f;
+pointerType()
+  matches "Foo *f", but does not match "int *a".
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>&gt;</td><td class="name" onclick="toggle('parenType0')"><a name="parenType0Anchor">parenType</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1ParenType.html">ParenType</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="parenType0"><pre>Matches ParenType nodes.
 

 
 
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>&gt;</td><td class="name" onclick="toggle('pointerType0')"><a name="pointerType0Anchor">pointerType</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1PointerType.html">PointerType</a>&gt;...</td></tr>
-<tr><td colspan="4" class="doc" id="pointerType0"><pre>Matches pointer types.
+<tr><td colspan="4" class="doc" id="pointerType0"><pre>Matches pointer types, but does not match Objective-C object pointer
+types.
 
 Given
   int *a;
   int &amp;b = *a;
   int c = 5;
+
+  @interface Foo
+  @end
+  Foo *f;
 pointerType()
-  matches "int *a"
+  matches "int *a", but does not match "Foo *f".
 </pre></td></tr>
 
 

 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>&gt;</td><td class="name" onclick="toggle('templateTypeParmType0')"><a name="templateTypeParmType0Anchor">templateTypeParmType</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1TemplateTypeParmType.html">TemplateTypeParmType</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="templateTypeParmType0"><pre>Matches template type parameter types.
+
+Example matches T, but not int.
+    (matcher = templateTypeParmType())
+  template &lt;typename T&gt; void f(int i);
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>&gt;</td><td class="name" onclick="toggle('type0')"><a name="type0Anchor">type</a></td><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Type.html">Type</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="type0"><pre>Matches Types in the clang AST.
 </pre></td></tr>

 <tr><td>Matcher&lt<a href="http://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(1));
+ matcher = objCMessageExpr(numSelectorArgs(0));
  matches self.bodyView in the code below
 
  matcher = objCMessageExpr(numSelectorArgs(2));

include/clang/ASTMatchers/ASTMatchers.h

   Stmt,
   ObjCMessageExpr> objcMessageExpr;
 
+/// \brief Matches Objective-C interface declarations.
+///
+/// Example matches Foo
+/// \code
+///   @interface Foo
+///   @end
+/// \endcode
+const internal::VariadicDynCastAllOfMatcher<
+  Decl,
+  ObjCInterfaceDecl> objcInterfaceDecl;
 
 /// \brief Matches expressions that introduce cleanups to be run at the end
 /// of the sub-expression's evaluation.

   Decl,
   UnresolvedUsingValueDecl> unresolvedUsingValueDecl;
 
+/// \brief Matches unresolved using value declarations that involve the
+/// typename.
+///
+/// Given
+/// \code
+///   template <typename T>
+///   struct Base { typedef T Foo; };
+///
+///   template<typename T>
+///   struct S : private Base<T> {
+///     using typename Base<T>::Foo;
+///   };
+/// \endcode
+/// unresolvedUsingTypenameDecl()
+///   matches \code using Base<T>::Foo \endcode
+const internal::VariadicDynCastAllOfMatcher<
+  Decl,
+  UnresolvedUsingTypenameDecl> unresolvedUsingTypenameDecl;
+
 /// \brief Matches constructor call expressions (including implicit ones).
 ///
 /// Example matches string(ptr, n) and ptr within arguments of f

 AST_MATCHER_P(
     QualType, pointsTo, internal::Matcher<QualType>,
     InnerMatcher) {
-  return (!Node.isNull() && Node->isPointerType() &&
+  return (!Node.isNull() && Node->isAnyPointerType() &&
           InnerMatcher.matches(Node->getPointeeType(), Finder, Builder));
 }
 

 ///   matches "A::* ptr"
 AST_TYPE_MATCHER(MemberPointerType, memberPointerType);
 
-/// \brief Matches pointer types.
+/// \brief Matches pointer types, but does not match Objective-C object pointer
+/// types.
 ///
 /// Given
 /// \code

 ///   int *a;
 ///   int &b = *a;
 ///   int c = 5;
+///
+///   @interface Foo
+///   @end
+///   Foo *f;
 /// \endcode
 /// pointerType()
-///   matches "int *a"
+///   matches "int *a", but does not match "Foo *f".
 AST_TYPE_MATCHER(PointerType, pointerType);
 
+/// \brief Matches an Objective-C object pointer type, which is different from
+/// a pointer type, despite being syntactically similar.
+///
+/// Given
+/// \code
+///   int *a;
+///
+///   @interface Foo
+///   @end
+///   Foo *f;
+/// \endcode
+/// pointerType()
+///   matches "Foo *f", but does not match "int *a".
+AST_TYPE_MATCHER(ObjCObjectPointerType, objcObjectPointerType);
+
 /// \brief Matches both lvalue and rvalue reference types.
 ///
 /// Given

 /// \c substTemplateTypeParmType() matches the type of 't' but not '1'
 AST_TYPE_MATCHER(SubstTemplateTypeParmType, substTemplateTypeParmType);
 
+/// \brief Matches template type parameter types.
+///
+/// Example matches T, but not int.
+///     (matcher = templateTypeParmType())
+/// \code
+///   template <typename T> void f(int i);
+/// \endcode
+AST_TYPE_MATCHER(TemplateTypeParmType, templateTypeParmType);
+
+/// \brief Matches injected class name types.
+///
+/// Example matches S s, but not S<T> s.
+///     (matcher = parmVarDecl(hasType(injectedClassNameType())))
+/// \code
+///   template <typename T> struct S {
+///     void f(S s);
+///     void g(S<T> s);
+///   };
+/// \endcode
+AST_TYPE_MATCHER(InjectedClassNameType, injectedClassNameType);
+
 /// \brief Matches declarations whose declaration context, interpreted as a
 /// Decl, matches \c InnerMatcher.
 ///

include/clang/ASTMatchers/ASTMatchersInternal.h

   /// matcher matches on it.
   bool matchesSpecialized(const QualType &Node, ASTMatchFinder *Finder,
                           BoundNodesTreeBuilder *Builder) const {
-    /// FIXME: Add other ways to convert...
     if (Node.isNull())
       return false;
-    return matchesDecl(Node->getAsTagDecl(), Finder, Builder);
+
+    if (auto *TD = Node->getAsTagDecl())
+      return matchesDecl(TD, Finder, Builder);
+    else if (auto *TT = Node->getAs<TypedefType>())
+      return matchesDecl(TT->getDecl(), Finder, Builder);
+    // Do not use getAs<TemplateTypeParmType> instead of the direct dyn_cast.
+    // Calling getAs will return the canonical type, but that type does not
+    // store a TemplateTypeParmDecl. We *need* the uncanonical type, if it is
+    // available, and using dyn_cast ensures that.
+    else if (auto *TTP = dyn_cast<TemplateTypeParmType>(Node.getTypePtr()))
+      return matchesDecl(TTP->getDecl(), Finder, Builder);
+    else if (auto *OCIT = Node->getAs<ObjCInterfaceType>())
+      return matchesDecl(OCIT->getDecl(), Finder, Builder);
+    else if (auto *UUT = Node->getAs<UnresolvedUsingType>())
+      return matchesDecl(UUT->getDecl(), Finder, Builder);
+    else if (auto *ICNT = Node->getAs<InjectedClassNameType>())
+      return matchesDecl(ICNT->getDecl(), Finder, Builder);
+    return false;
   }
 
   /// \brief Gets the TemplateDecl from a TemplateSpecializationType

lib/ASTMatchers/Dynamic/Registry.cpp

   REGISTER_MATCHER(implicitCastExpr);
   REGISTER_MATCHER(incompleteArrayType);
   REGISTER_MATCHER(initListExpr);
+  REGISTER_MATCHER(injectedClassNameType);
   REGISTER_MATCHER(innerType);
   REGISTER_MATCHER(integerLiteral);
   REGISTER_MATCHER(isAnonymous);

   REGISTER_MATCHER(nullStmt);
   REGISTER_MATCHER(numSelectorArgs);
   REGISTER_MATCHER(ofClass);
+  REGISTER_MATCHER(objcInterfaceDecl);
   REGISTER_MATCHER(objcMessageExpr);
+  REGISTER_MATCHER(objcObjectPointerType);
   REGISTER_MATCHER(on);
   REGISTER_MATCHER(onImplicitObjectArgument);
   REGISTER_MATCHER(operatorCallExpr);

   REGISTER_MATCHER(templateArgument);
   REGISTER_MATCHER(templateArgumentCountIs);
   REGISTER_MATCHER(templateSpecializationType);
+  REGISTER_MATCHER(templateTypeParmType);
   REGISTER_MATCHER(temporaryObjectExpr);
   REGISTER_MATCHER(thisExpr);
   REGISTER_MATCHER(throughUsingDecl);

   REGISTER_MATCHER(unaryTransformType);
   REGISTER_MATCHER(unless);
   REGISTER_MATCHER(unresolvedConstructExpr);
+  REGISTER_MATCHER(unresolvedUsingTypenameDecl);
   REGISTER_MATCHER(unresolvedUsingValueDecl);
   REGISTER_MATCHER(userDefinedLiteral);
   REGISTER_MATCHER(usingDecl);

unittests/ASTMatchers/ASTMatchersTest.cpp

                        varDecl(hasType(namedDecl(hasName("S"))))));
 }
 
+TEST(TypeMatcher, MatchesDeclTypes) {
+  // TypedefType -> TypedefNameDecl
+  EXPECT_TRUE(matches("typedef int I; void f(I i);",
+                      parmVarDecl(hasType(namedDecl(hasName("I"))))));
+  // ObjCObjectPointerType
+  EXPECT_TRUE(matchesObjC("@interface Foo @end void f(Foo *f);",
+                          parmVarDecl(hasType(objcObjectPointerType()))));
+  // ObjCObjectPointerType -> ObjCInterfaceType -> ObjCInterfaceDecl
+  EXPECT_TRUE(matchesObjC(
+      "@interface Foo @end void f(Foo *f);",
+      parmVarDecl(hasType(pointsTo(objcInterfaceDecl(hasName("Foo")))))));
+  // TemplateTypeParmType
+  EXPECT_TRUE(matches("template <typename T> void f(T t);",
+                      parmVarDecl(hasType(templateTypeParmType()))));
+  // TemplateTypeParmType -> TemplateTypeParmDecl
+  EXPECT_TRUE(matches("template <typename T> void f(T t);",
+                      parmVarDecl(hasType(namedDecl(hasName("T"))))));
+  // InjectedClassNameType
+  EXPECT_TRUE(matches("template <typename T> struct S {"
+                      "  void f(S s);"
+                      "};",
+                      parmVarDecl(hasType(injectedClassNameType()))));
+  EXPECT_TRUE(notMatches("template <typename T> struct S {"
+                         "  void g(S<T> s);"
+                         "};",
+                         parmVarDecl(hasType(injectedClassNameType()))));
+  // InjectedClassNameType -> CXXRecordDecl
+  EXPECT_TRUE(matches("template <typename T> struct S {"
+                      "  void f(S s);"
+                      "};",
+                      parmVarDecl(hasType(namedDecl(hasName("S"))))));
+
+  static const char Using[] = "template <typename T>"
+                              "struct Base {"
+                              "  typedef T Foo;"
+                              "};"
+                              ""
+                              "template <typename T>"
+                              "struct S : private Base<T> {"
+                              "  using typename Base<T>::Foo;"
+                              "  void f(Foo);"
+                              "};";
+  // UnresolvedUsingTypenameDecl
+  EXPECT_TRUE(matches(Using, unresolvedUsingTypenameDecl(hasName("Foo"))));
+  // UnresolvedUsingTypenameType -> UnresolvedUsingTypenameDecl
+  EXPECT_TRUE(matches(Using, parmVarDecl(hasType(namedDecl(hasName("Foo"))))));
+}
+
 TEST(Matcher, BindMatchedNodes) {
   DeclarationMatcher ClassX = has(recordDecl(hasName("::X")).bind("x"));