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 ↗

(On Diff #440443)

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 ↗

(On Diff #440450)

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/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(specifiesNamespace);
   REGISTER_MATCHER(specifiesType);
   REGISTER_MATCHER(specifiesTypeLoc);
   REGISTER_MATCHER(statementCountIs);
   REGISTER_MATCHER(staticAssertDecl);
   REGISTER_MATCHER(stmt);
   REGISTER_MATCHER(stmtExpr);
   REGISTER_MATCHER(stringLiteral);
+  REGISTER_MATCHER(objCStringLiteral);
   REGISTER_MATCHER(substNonTypeTemplateParmExpr);
   REGISTER_MATCHER(substTemplateTypeParmType);
   REGISTER_MATCHER(switchCase);
   REGISTER_MATCHER(switchStmt);
   REGISTER_MATCHER(tagDecl);
   REGISTER_MATCHER(tagType);
   REGISTER_MATCHER(templateArgument);
   REGISTER_MATCHER(templateArgumentCountIs);

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) "