[Format] Fix 'auto x(T&&, T &&)->F' with PAS_Left.

[sammccall]

Summary

An heuristic targetting x && x->foo was targed overly broadly and caused the
last T&& to be treated as a binary operator.

[sammccall]

clang/lib/Format/TokenAnnotator.cpp

1804

(while here: the NextToken check was redundant as we deref it above already)

[merge_guards_bot]

Unit tests: fail. 62136 tests passed, 5 failed and 811 were skipped.

failed: libc++.std/language_support/cmp/cmp_partialord/partialord.pass.cpp
failed: libc++.std/language_support/cmp/cmp_strongeq/cmp.strongeq.pass.cpp
failed: libc++.std/language_support/cmp/cmp_strongord/strongord.pass.cpp
failed: libc++.std/language_support/cmp/cmp_weakeq/cmp.weakeq.pass.cpp
failed: libc++.std/language_support/cmp/cmp_weakord/weakord.pass.cpp

clang-tidy: pass.

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

clang/lib/Format/TokenAnnotator.cpp

if (PrevToken->Tok.isLiteral() ||
         NextToken->isUnaryOperator() ||
         // If we know we're in a template argument, there are no named
         // declarations. Thus, having an identifier on the right-hand side
         // indicates a binary operator.
         (InTemplateArgument && NextToken->Tok.isAnyIdentifier()))
       return TT_BinaryOperator;
 
     // "&&(" is quite unlikely to be two successive unary "&".
-    if (Tok.is(tok::ampamp) && NextToken && NextToken->is(tok::l_paren))
+    if (Tok.is(tok::ampamp) && NextToken->is(tok::l_paren))
       return TT_BinaryOperator;
 
     // This catches some cases where evaluation order is used as control flow:
     //   aaa && aaa->f();
+    if (NextToken->Tok.isAnyIdentifier()) {
       const FormatToken *NextNextToken = NextToken->getNextNonComment();
       if (NextNextToken && NextNextToken->is(tok::arrow))
         return TT_BinaryOperator;
+    }
 
     // It is very unlikely that we are going to find a pointer or reference type
     // definition on the RHS of an assignment.
     if (IsExpression && !Contexts.back().CaretFound)
       return TT_BinaryOperator;
 
     return TT_PointerOrReference;
   }

clang/unittests/Format/FormatTest.cpp

TEST_F(FormatTest, UnderstandsUsesOfStarAndAmp) {
   verifyFormat("x = *a(x) = *a(y);", Left);
   verifyFormat("for (;; *a = b) {\n}", Left);
   verifyFormat("return *this += 1;", Left);
   verifyFormat("throw *x;", Left);
   verifyFormat("delete *x;", Left);
   verifyFormat("typedef typeof(int(int, int))* MyFuncPtr;", Left);
   verifyFormat("[](const decltype(*a)* ptr) {}", Left);
   verifyFormat("typedef typeof /*comment*/ (int(int, int))* MyFuncPtr;", Left);
+  verifyFormat("auto x(A&&, B&&, C&&) -> D;", Left);
+  verifyFormat("auto x = [](A&&, B&&, C&&) -> D {};", Left);
+  verifyFormat("template <class T> X(T&&, T&&, T&&) -> X<T>;", Left);
 
   verifyIndependentOfContext("a = *(x + y);");
   verifyIndependentOfContext("a = &(x + y);");
   verifyIndependentOfContext("*(x + y).call();");
   verifyIndependentOfContext("&(x + y)->call();");
   verifyFormat("void f() { &(*I).first; }");
 
   verifyIndependentOfContext("f(b * /* confusing comment */ ++c);");