[clang-format] Fix braced initializer formatting with templated base class initializer

[galenelias]

Summary

This fixes https://github.com/llvm/llvm-project/issues/64134 which
is a regression from https://reviews.llvm.org/D150403 where I
added logic to distinguish adjacent braces blocks between being braced
initializers or adjacent scopes by looking at the token before the first
opening brace to see if it is part of a class initializer list.

However, this logic fails to match initialization of a templated base
class initializer, because in that scenario the 'identifier' actually
ends in a >, so isn't detected. I am extending the logic to just also
detect > explicitly to be recognized as the braced initializer syntax.
Hopefully there aren't many more holes in the detection logic here.

[HazardyKnusperkeks]

clang/unittests/Format/FormatTest.cpp

13461

Please also add nested templates.

[galenelias]

clang/unittests/Format/FormatTest.cpp

13461

Ok, added A() : Base<Foo<int>>{} {} as a test case. I think that's what you mean by nested templates, but let me know if I misunderstood.

clang/lib/Format/UnwrappedLineParser.cpp

case tok::r_brace:
               NextTok->isOneOf(tok::comma, tok::period, tok::colon,
                                tok::r_paren, tok::r_square, tok::ellipsis);
 
           // Distinguish between braced list in a constructor initializer list
           // followed by constructor body, or just adjacent blocks.
           ProbablyBracedList =
               ProbablyBracedList ||
               (NextTok->is(tok::l_brace) && LBraceStack.back().PrevTok &&
-               LBraceStack.back().PrevTok->is(tok::identifier));
+               LBraceStack.back().PrevTok->isOneOf(tok::identifier,
+                                                   tok::greater));
 
           ProbablyBracedList =
               ProbablyBracedList ||
               (NextTok->is(tok::identifier) &&
                !PrevTok->isOneOf(tok::semi, tok::r_brace, tok::l_brace));
 
           ProbablyBracedList = ProbablyBracedList ||
                                (NextTok->is(tok::semi) &&

clang/unittests/Format/FormatTest.cpp

verifyFormat("class C : public A {\n"
                "    void f() { int i{2}; }\n"
                "  };\n"
                "};");
   verifyFormat("#define A {a, a},");
   // Don't confuse braced list initializers with compound statements.
   verifyFormat(
       "class A {\n"
       "  A() : a{} {}\n"
+      "  A() : Base<int>{} {}\n"
+      "  A() : Base<Foo<int>>{} {}\n"
       "  A(int b) : b(b) {}\n"
       "  A(int a, int b) : a(a), bs{{bs...}} { f(); }\n"
       "  int a, b;\n"
       "  explicit Expr(const Scalar<Result> &x) : u{Constant<Result>{x}} {}\n"
       "  explicit Expr(Scalar<Result> &&x) : u{Constant<Result>{std::move(x)}} "
       "{}\n"
       "};");