Revert "Implement nullPointerConstant() using a better API."

[steveire]

Summary

This reverts commit 9148302a (2019-08-22) which broke the pre-existing
unit test for the matcher. Also revert commit 518b2266 (Fix the
nullPointerConstant() test to get bots back to green., 2019-08-22) which
incorrectly changed the test to expect the broken behavior.

[njames93]

I'm a little confused here, Typically if a commit is breaking bots a review doesn't need to be opened to revert it?

[steveire]

As discussed elsewhere, the bots are not broken. The changes reverted here were made in 2019.

[goncharov]

Hi @steveire! Sorry but I reverted this revert. Could you please give some context of "discussed elsewhere" and "pre-existing unit test for the matcher"? @aaron.ballman for cc

[goncharov]

I have relanded this in https://github.com/llvm/llvm-project/commit/3b148d6f991181a1b8f089c4bc2126e1a6c1212d . My apologies

[steveire]

In D96665#2578718, @goncharov wrote:

I have relanded this in https://github.com/llvm/llvm-project/commit/3b148d6f991181a1b8f089c4bc2126e1a6c1212d . My apologies

@goncharov Why did you revert this change?

[steveire]

In D96665#2578635, @goncharov wrote:

Hi @steveire! Sorry but I reverted this revert. Could you please give some context of "discussed elsewhere" and "pre-existing unit test for the matcher"? @aaron.ballman for cc

@njames93 didn't realize that the offending commits were from 2019, as I wrote in the comment. That's what I told him "elsewhere".

I plan to re-apply this revert. If you have a reason I shouldn't do that, please say what it is.

[steveire]

In D96665#2579422, @steveire wrote:

In D96665#2578635, @goncharov wrote:

Hi @steveire! Sorry but I reverted this revert. Could you please give some context of "discussed elsewhere" and "pre-existing unit test for the matcher"? @aaron.ballman for cc

@njames93 didn't realize that the offending commits were from 2019, as I wrote in the comment. That's what I told him "elsewhere".

I plan to re-apply this revert. If you have a reason I shouldn't do that, please say what it is.

@goncharov I see you already re-landed it. In future please open review requests for things like this to avoid confusion.

clang/include/clang/ASTMatchers/ASTMatchers.h

 ///   void *v3 = __null; // GNU extension
 ///   char *cp = (char *)0;
 ///   int *ip = 0;
 ///   int i = 0;
 /// \endcode
 /// expr(nullPointerConstant())
 ///   matches the initializer for v1, v2, v3, cp, and ip. Does not match the
 ///   initializer for i.
-AST_MATCHER(Expr, nullPointerConstant) {
-  return Node.isNullPointerConstant(Finder->getASTContext(),
-                                    Expr::NPC_ValueDependentIsNull);
+AST_MATCHER_FUNCTION(internal::Matcher<Expr>, nullPointerConstant) {
+  return anyOf(
+      gnuNullExpr(), cxxNullPtrLiteralExpr(),
+      integerLiteral(equals(0), hasParent(expr(hasType(pointerType())))));
 }
 
 /// Matches the DecompositionDecl the binding belongs to.
 ///
 /// For example, in:
 /// \code
 /// void foo()
 /// {

clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp

 }
 
 TEST_P(ASTMatchersTest, NullPointerConstant) {
   EXPECT_TRUE(matches("#define NULL ((void *)0)\n"
                       "void *v1 = NULL;",
                       expr(nullPointerConstant())));
   EXPECT_TRUE(matches("char *cp = (char *)0;", expr(nullPointerConstant())));
   EXPECT_TRUE(matches("int *ip = 0;", expr(nullPointerConstant())));
-  EXPECT_TRUE(matches("int i = 0;", expr(nullPointerConstant())));
+  EXPECT_FALSE(matches("int i = 0;", expr(nullPointerConstant())));
 }
 
 TEST_P(ASTMatchersTest, NullPointerConstant_GNUNull) {
   if (!GetParam().isCXX()) {
     return;
   }
 
   EXPECT_TRUE(matches("void *p = __null;", expr(nullPointerConstant())));