A newline is added after a string token if the next 2 tokens are lessless and string

[JvdGlind]

Bugzilla Link	45018
Version	trunk
OS	Windows NT
Attachments	File to verify two streamed strings aren't split

Extended Description

Given the code:

QStringList() << "something" << "something" << variable;

If I then run clang-format with the default config file, the output is the following code:

QStringList() << "something"
<< "something" << variable

What I expected, was that it stays on a single line, unless it exceeds the column limit and possible penalties. In this case, untouched.

It stays untouched when I add a variable in between:

QStringList() << "something" << a << "something" << variable;

Looking at the code, I noticed that somebody intentionally introduced this to split endline characters in commit df28f7b8dd6a032515109de4ff5b4067be95da8e (currently at lib/Format/TokenAnnotator.cpp, line 3073).

In the attachment I added a file with a slightly different example that I used when debugging clang-format.

[llvmbot]

This is a really annoying issue, especially because the results seem pretty random: If you use QStringLiteral() the strings are not wrapped.

One workaround for the usecase you described would be to use initializer lists, which is formatted really well and looks even better IMHO.

But in QTest::newRow() calls one can not use initializer lists and using QStringLiteral and such would add unwanted noise. Especially with the many usages in the KDE codebase this becomes a problem.

For example:
QTest::newRow("test") << "" << "" << "" << "" << "" << 1 << 1 << 1 << 1 << 1;

would be formatted to

QTest::newRow("test") << ""
<< ""
<< ""
<< ""
<< "" << 1 << 1 << 1 << 1 << 1;

I would appreciate if the developers could look into this :)

[dan-42]

Using LLVM 15.0.0 on Windows we have a similar issue.
We use the operator<< for collecting sigslot_connection when calling connect(sigslot_slot) in our sigslot library
code looks like this:

connection_store_ 
  << some_module.signals().scanning_started.connect(
     [this]()
     { 
        /*business logic*/
     })
  << some_module.signals().scanning_finished.connect(
    [this](...)
    {
      /*business logic*/
    }
    });

Clang-format does this:

connection_store_ << some_module.signals().on_started.connect(
                         [this]()
                         { 
                            /*business logic*/
                         })

                    << some_module.signals().on_finished.connect(
                         [this](...)
                         {
                            /*business logic*/
                         }
                          });

I suggest having an option allowing specific behaviour, something like

BreakAfterStreamOperator: {Leave, Never, Always, FitLine, ...}

Anyone else having issues in general with the stream operators?
Is there any better suggestion?

[mohad12211]

same issue here, I agree with the above suggestion.

[owenca]

@dan-42, it seems that clang-format 17 formats your example alright although the indent of the comments are wrong, which you can open another issue for.