[clang-format] fix handling of consecutive unary operators

[kevinl]

Summary

Code that used to be formatted as if (! + object) { is now formatted as if (!+object) {
(we have a particular object in our codebase where unary operator+ is overloaded to return the underlying value, which in this case is a bool)

We still preserve the TypeScript behavior where ! is a trailing non-null operator. (This is already tested by an existing unit test in FormatTestJS.cpp)

It doesn't appear like handling of consecutive unary operators are tested in general, so I added another test for completeness

[krasimir]

lib/Format/TokenAnnotator.cpp

1495

I think that TypeScript has both if (!cond) and x!. I'd expect that if (!+i) {\n} is also handled in the TypeScript case. Could you add a test for this for TypeScript please.

[kevinl]

Simplified the heuristic logic, which extends the fix to TypeScript as well

lib/Format/TokenAnnotator.cpp

1495

Turns out the comment below was misleading. The x! operator is classified as TT_JsNonNullAssertion and not TT_UnaryOperator, so removing the check for tok::exclaim entirely fixes if (!+i) {\n} in TypeScript as well as C++. Tests are now added for both languages

[krasimir]

Thank you! Do you have commit access or should I commit this for you?

[kevinl]

I do not have commit access.

Would appreciate you committing it for me. Thanks!

[kevinl]

@krasimir ping?

would appreciate you committing this for me. thanks!

lib/Format/TokenAnnotator.cpp

TokenType determineStarAmpUsage(const FormatToken &Tok, bool IsExpression,
     return TT_PointerOrReference;
   }
 
   TokenType determinePlusMinusCaretUsage(const FormatToken &Tok) {
     const FormatToken *PrevToken = Tok.getPreviousNonComment();
     if (!PrevToken)
       return TT_UnaryOperator;
 
-    if (PrevToken->isOneOf(TT_CastRParen, TT_UnaryOperator) &&
-        !PrevToken->is(tok::exclaim))
-      // There aren't any trailing unary operators except for TypeScript's
-      // non-null operator (!). Thus, this must be squence of leading operators.
+    if (PrevToken->isOneOf(TT_CastRParen, TT_UnaryOperator))
+      // This must be a sequence of leading unary operators.
       return TT_UnaryOperator;
 
     // Use heuristics to recognize unary operators.
     if (PrevToken->isOneOf(tok::equal, tok::l_paren, tok::comma, tok::l_square,
                            tok::question, tok::colon, tok::kw_return,
                            tok::kw_case, tok::at, tok::l_brace))
       return TT_UnaryOperator;
 

unittests/Format/FormatTest.cpp

TEST_F(FormatTest, UnderstandsUnaryOperators) {
   verifyFormat("if (i != -1) {\n}");
   verifyFormat("if (i > -1) {\n}");
   verifyFormat("if (i < -1) {\n}");
   verifyFormat("++(a->f());");
   verifyFormat("--(a->f());");
   verifyFormat("(a->f())++;");
   verifyFormat("a[42]++;");
   verifyFormat("if (!(a->f())) {\n}");
+  verifyFormat("if (!+i) {\n}");
+  verifyFormat("~&a;");
 
   verifyFormat("a-- > b;");
   verifyFormat("b ? -a : c;");
   verifyFormat("n * sizeof char16;");
   verifyFormat("n * alignof char16;", getGoogleStyle());
   verifyFormat("sizeof(char);");
   verifyFormat("alignof(char);", getGoogleStyle());
 

unittests/Format/FormatTestJS.cpp

verifyFormat("#!/usr/bin/env node\n"
                "#!/usr/bin/env node\n"
                "var x   =  hello();");
 }
 
 TEST_F(FormatTestJS, NonNullAssertionOperator) {
   verifyFormat("let x = foo!.bar();\n");
   verifyFormat("let x = foo ? bar! : baz;\n");
   verifyFormat("let x = !foo;\n");
+  verifyFormat("if (!+a) {\n}");
   verifyFormat("let x = foo[0]!;\n");
   verifyFormat("let x = (foo)!;\n");
   verifyFormat("let x = x(foo!);\n");
   verifyFormat(
       "a.aaaaaa(a.a!).then(\n"
       "    x => x(x));\n",
       getGoogleJSStyleWithColumns(20));
   verifyFormat("let x = foo! - 1;\n");