[clang-format] Fix a bug that misformats Access Specifier after *[]

[owenpan]

Summary

Fixes https://github.com/llvm/llvm-project/issues/55132.

[curdeius]

Looks more or less correct, but I am afraid that this change may misbehave in some rare cases.
Consider *[](auto *x) { return x; }();, so an immediately invoked lambda returning a pointer.
It seems to be correctly formatted currently, but I don't see any test on it.
Could you add a test for this please?

[owenpan]

Also checks the token before * and adds a test case.

[owenpan]

In D124589#3479241, @curdeius wrote:

Looks more or less correct, but I am afraid that this change may misbehave in some rare cases.
Consider *[](auto *x) { return x; }();, so an immediately invoked lambda returning a pointer.
It seems to be correctly formatted currently, but I don't see any test on it.
Could you add a test for this please?

Good catch!

[curdeius]

clang/unittests/Format/FormatTest.cpp

3342

How about int const *, const int*? Is const & co. a simple type specifier?

[HazardyKnusperkeks]

I currently don't know exactly how isSimpleTypeSpecifier works, but what is with
auto x = Foo * []{return 5;}();
auto x = Foo * *[]{static y = 5; return &y;}();

[owenpan]

Instead of looking back, look ahead in tryToParseLambdaIntroducer().

[owenpan]

Now that we look ahead instead of looking back, it doesn't matter what comes before *[] or [].

clang/unittests/Format/FormatTest.cpp

3342

It doesn't matter what comes before *[] now that we look ahead for a >.

clang/lib/Format/UnwrappedLineParser.cpp

bool UnwrappedLineParser::tryToParseLambda() {
   FormatTok->setFinalizedType(TT_LambdaLBrace);
   LSquare.setFinalizedType(TT_LambdaLSquare);
   parseChildBlock();
   return true;
 }
 
 bool UnwrappedLineParser::tryToParseLambdaIntroducer() {
   const FormatToken *Previous = FormatTok->Previous;
-  if (Previous &&
-      (Previous->isOneOf(tok::identifier, tok::kw_operator, tok::kw_new,
+  if (Previous) {
+    const FormatToken *PrevPrev = Previous->Previous;
+    if (Previous->isOneOf(tok::identifier, tok::kw_operator, tok::kw_new,
                           tok::kw_delete, tok::l_square) ||
         FormatTok->isCppStructuredBinding(Style) || Previous->closesScope() ||
-       Previous->isSimpleTypeSpecifier())) {
+        Previous->isSimpleTypeSpecifier() ||
+        (Previous->is(tok::star) && PrevPrev &&
+         PrevPrev->isSimpleTypeSpecifier())) {
       nextToken();
       return false;
     }
+  }
   nextToken();
   if (FormatTok->is(tok::l_square))
     return false;
   parseSquare(/*LambdaIntroducer=*/true);
   return true;
 }
 
 void UnwrappedLineParser::tryToParseJSFunction() {

clang/unittests/Format/FormatTest.cpp

TEST_F(FormatTest, UnderstandsAccessSpecifiers) {
   verifyFormat("public ^ private;");
   verifyFormat("public ^= private;");
   verifyFormat("public | private;");
   verifyFormat("public |= private;");
   verifyFormat("auto x = private ? 1 : 2;");
   verifyFormat("if (public == private)\n");
   verifyFormat("void foo(public, private)");
   verifyFormat("public::foo();");
+
+  verifyFormat("class A {\n"
+               "public:\n"
+               "  std::unique_ptr<int *[]> b() { return nullptr; }\n"
+               "\n"
+               "private:\n"
+               "  int c;\n"
+               "};");
 }
 
 TEST_F(FormatTest, SeparatesLogicalBlocks) {
   EXPECT_EQ("class A {\n"
             "public:\n"
             "  void f();\n"
             "\n"
             "private:\n"
TEST_F(FormatTest, FormatsLambdas) {
   verifyFormat("int i = a[a][a]->f();");
   verifyFormat("int i = (*b)[a]->f();");
 
   // Other corner cases.
   verifyFormat("void f() {\n"
                "  bar([]() {} // Did not respect SpacesBeforeTrailingComments\n"
                "  );\n"
                "}");
+  verifyFormat("auto k = *[](int *j) { return j; }(&i)");
 
   // Lambdas created through weird macros.
   verifyFormat("void f() {\n"
                "  MACRO((const AA &a) { return 1; });\n"
                "  MACRO((AA &a) { return 1; });\n"
                "}");
 
   verifyFormat("if (blah_blah(whatever, whatever, [] {\n"