Adds AST Matcher for ObjCStringLiteral

[NoQ]

Matcher tests are written as unittests in unittests/ASTMatchers, I don't think you need to make an entire new check for that hmmm.

[t-rasmud]

Documentation edits and other fixes, thanks to suggestions from @ziqingluo-90

[NoQ]

Looks great, thanks!

clang/docs/LibASTMatchersReference.html

2041

I think it's more appropriate for this documentation to mention the entire literal so that the reader didn't assume that @ is a different AST node that needs to be captured separately.

[aaron.ballman]

We typically don't add AST matchers until we have a need for them to be used in-tree (ASTMatchers.h is already really expensive to parse; adding matchers for everything possible with AST nodes would be prohibitively expensive). However, this is a case that really seems like it doesn't need to wait for an in-tree use because of how foundational the matcher is, so I think it's fine to add as-is.

clang/docs/LibASTMatchersReference.html

2038

It looks like this documentation was added manually -- it should actually live in the ASTMatchers.h header file, and then you run clang/docs/tools/dump_ast_matchers.py to generate this HTML file automatically.

clang/include/clang/ASTMatchers/ASTMatchers.h

1518–1519

You should add your documentation comments above this declaration.

[t-rasmud]

Removes manually added documentation and adds it in the header file.

[NoQ]

Yes the use case is coming up in D126097; it's not used yet because hasDescendant(StringLiteral) is used to skip it but this matchert would be a more precise solution (yes there's an actual StringLiteral inside ObjCStringLiteral).

[aaron.ballman]

The only things left to do are: regenerate the documentation by running clang/docs/tools/dump_ast_matchers.py and add a release note for the new matcher, but otherwise this looks good to me.

In D128103#3617156, @NoQ wrote:

Yes the use case is coming up in D126097; it's not used yet because hasDescendant(StringLiteral) is used to skip it but this matchert would be a more precise solution (yes there's an actual StringLiteral inside ObjCStringLiteral).

Ah, great to hear this will be used quickly in tree too!

[aaron.ballman]

LGTM! Do you need me to commit on your behalf? If so, what name and email address would you like me to use for patch attribution?

[t-rasmud]

In D128103#3622223, @aaron.ballman wrote:

LGTM! Do you need me to commit on your behalf? If so, what name and email address would you like me to use for patch attribution?

Thank you @aaron.ballman. I believe I have the permissions to commit, so I can land the patch.

clang/docs/LibASTMatchersReference.html

 
 The innermost message send invokes the "alloc" class method on the
 NSString class, while the outermost message send invokes the
 "initWithString" instance method on the object returned from
 NSString's "alloc". This matcher should match both message sends.
   [[NSString alloc] initWithString:@"Hello"]
 </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('stringLiteral0')"><a name="stringLiteral0Anchor">objcStringLiteral</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1ObjCStringLiteral.html">ObjCStringLiteral</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="stringLiteral0"><pre>Matches objective-C string literals.
+
+Example matches @"abcd"
+  NSString *s = @"abcd";
+</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('objcThrowStmt0')"><a name="objcThrowStmt0Anchor">objcThrowStmt</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1ObjCAtThrowStmt.html">ObjCAtThrowStmt</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="objcThrowStmt0"><pre>Matches Objective-C statements.
 
 Example matches @throw obj;
 </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('stringLiteral0')"><a name="stringLiteral0Anchor">stringLiteral</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1StringLiteral.html">StringLiteral</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="stringLiteral0"><pre>Matches string literals (also matches wide string literals).
 
 Example matches "abcd", L"abcd"
   char *s = "abcd";
   wchar_t *ws = L"abcd";
 </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('substNonTypeTemplateParmExpr0')"><a name="substNonTypeTemplateParmExpr0Anchor">substNonTypeTemplateParmExpr</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1SubstNonTypeTemplateParmExpr.html">SubstNonTypeTemplateParmExpr</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="substNonTypeTemplateParmExpr0"><pre>Matches substitutions of non-type template parameters.
 
 Given
   template &lt;int N&gt;
   struct A { static const int n = N; };
   struct B : public A&lt;42&gt; {};
 substNonTypeTemplateParmExpr()

clang/include/clang/ASTMatchers/ASTMatchers.h

 /// "initWithString" instance method on the object returned from
 /// NSString's "alloc". This matcher should match both message sends.
 /// \code
 ///   [[NSString alloc] initWithString:@"Hello"]
 /// \endcode
 extern const internal::VariadicDynCastAllOfMatcher<Stmt, ObjCMessageExpr>
     objcMessageExpr;
 
+extern const internal::VariadicDynCastAllOfMatcher<Stmt, ObjCStringLiteral>
+    objcStringLiteral;
+
 /// Matches Objective-C interface declarations.
 ///
 /// Example matches Foo
 /// \code
 ///   @interface Foo
 ///   @end
 /// \endcode
 extern const internal::VariadicDynCastAllOfMatcher<Decl, ObjCInterfaceDecl>

clang/lib/ASTMatchers/ASTMatchersInternal.cpp

 const internal::VariadicDynCastAllOfMatcher<Stmt, CXXCatchStmt> cxxCatchStmt;
 const internal::VariadicDynCastAllOfMatcher<Stmt, CXXTryStmt> cxxTryStmt;
 const internal::VariadicDynCastAllOfMatcher<Stmt, CXXThrowExpr> cxxThrowExpr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, NullStmt> nullStmt;
 const internal::VariadicDynCastAllOfMatcher<Stmt, AsmStmt> asmStmt;
 const internal::VariadicDynCastAllOfMatcher<Stmt, CXXBoolLiteralExpr>
     cxxBoolLiteral;
 const internal::VariadicDynCastAllOfMatcher<Stmt, StringLiteral> stringLiteral;
+const internal::VariadicDynCastAllOfMatcher<Stmt, ObjCStringLiteral> objcStringLiteral;
 const internal::VariadicDynCastAllOfMatcher<Stmt, CharacterLiteral>
     characterLiteral;
 const internal::VariadicDynCastAllOfMatcher<Stmt, IntegerLiteral>
     integerLiteral;
 const internal::VariadicDynCastAllOfMatcher<Stmt, FloatingLiteral> floatLiteral;
 const internal::VariadicDynCastAllOfMatcher<Stmt, ImaginaryLiteral> imaginaryLiteral;
 const internal::VariadicDynCastAllOfMatcher<Stmt, FixedPointLiteral>
     fixedPointLiteral;

clang/lib/ASTMatchers/Dynamic/Registry.cpp

RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(objcInterfaceDecl);
   REGISTER_MATCHER(objcIvarDecl);
   REGISTER_MATCHER(objcIvarRefExpr);
   REGISTER_MATCHER(objcMessageExpr);
   REGISTER_MATCHER(objcMethodDecl);
   REGISTER_MATCHER(objcObjectPointerType);
   REGISTER_MATCHER(objcPropertyDecl);
   REGISTER_MATCHER(objcProtocolDecl);
+  REGISTER_MATCHER(objcStringLiteral);
   REGISTER_MATCHER(objcThrowStmt);
   REGISTER_MATCHER(objcTryStmt);
   REGISTER_MATCHER(ofClass);
   REGISTER_MATCHER(ofKind);
   REGISTER_MATCHER(ompDefaultClause);
   REGISTER_MATCHER(ompExecutableDirective);
   REGISTER_MATCHER(on);
   REGISTER_MATCHER(onImplicitObjectArgument);

clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp

EXPECT_TRUE(matchesObjC(Objc1String, objcMessageExpr(hasSelector("contents"),
                                                        hasUnarySelector())));
   EXPECT_TRUE(matchesObjC(Objc1String, objcMessageExpr(hasSelector("contents"),
                                                        numSelectorArgs(0))));
   EXPECT_TRUE(
       matchesObjC(Objc1String, objcMessageExpr(matchesSelector("uppercase*"),
                                                argumentCountIs(0))));
 }
 
+TEST(ASTMatchersTestObjC, ObjCStringLiteral) {
+
+  StringRef Objc1String = "@interface NSObject "
+                          "@end "
+                          "@interface NSString "
+                          "@end "
+                          "@interface Test : NSObject "
+                          "+ (void)someFunction:(NSString *)Desc; "
+                          "@end "
+                          "@implementation Test "
+                          "+ (void)someFunction:(NSString *)Desc { "
+                          "    return; "
+                          "} "
+                          "- (void) foo { "
+                          "    [Test someFunction:@\"Ola!\"]; "
+                          "}\n"
+                          "@end ";
+    EXPECT_TRUE(matchesObjC(Objc1String, objcStringLiteral()));
+}
+
 TEST(ASTMatchersTestObjC, ObjCDecls) {
   StringRef ObjCString = "@protocol Proto "
                          "- (void)protoDidThing; "
                          "@end "
                          "@interface Thing "
                          "@property int enabled; "
                          "@end "
                          "@interface Thing (ABC) "