[cfe-dev] TextDiagnostic: Tab handling and newlines in FixIt lines

[Firat Kasmis via cfe-dev]

Running check-clang-misc gives me an error for tabstop.c. The postfix
doesn't seem right and messes around with the tabstop. So,

"Hallo...Tab.....Tab.....X" was right and
"Hallo........Tab........Tab........X" wrong, since tabstop is default 8.

<>
Hallo...Tab.....Tab.....X
Hallo.......Tab.....Tab.....X
<>

Is also correct, since the messages are fired at different indentation
levels. So, after I made a complete turn, how do I display a multi-line
diagnostic and FixItHint.

I have:

DeclStmt declstmt: int a, b, c;
std::string allSingleDecls = "int a;\nint b;\nint c;";   //
<<--- necessary whitespaces to keep indentation might be inserted

auto Diag = diag(declStmt->getSourceRange().getBegin(), "declaration
statement can be split up into single line declarations");
Diag << FixItHint::CreateReplacement(declStmt->getSourceRange(),
allSingleDecls);

The FixIt is applied correct to the source file with -fix, but I would like
to see a nice diagnostic-output as well.

Thanks.

2016-11-02 19:34 GMT+01:00 Firat Kasmis <firat.kasmis at gmail.com>:

> Hi,
>
> I am just struggling around with tabs and new lines in TextDiagnostic.cpp.
> Right now, I am writing a clang-tidy check to transform
>
> int a, b, c;
> int k1 = 0, k2 = 0;
>
> into
>
> int a;
> int b;
> int c;
>
> int k1 = 0;
> int k2 = 0;
>
> and came across some issues.
>
>
> 1. buildFixItInsertionLine ignores lines with \n or \r. Is there any
> specific reason not to show these lines (despite that everything is called
> Line and not Lines and probably not checked for Lines)?
> 2. I am getting odd results for lines containing multiple tabs:
>
>
> Diag << FixItHint::CreateInsertion(..., "Hallo\tTab\tTab\tX"); // gets
> fired twice (for a,b,c and k1,k2 line)
>
> ==>
>
> Hallo...Tab.....Tab.....X
> Hallo.......Tab.....Tab.....X
>
>
> Seems to be that
>
> static int bytesSincePreviousTabOrLineBegin(StringRef SourceLine, size_t
> i) {
>   int bytes = 0;
>   while (0<i) {
>     if (SourceLine[--i]=='\t')
>       break;
>     ++bytes;
>   }
>   return bytes;
> }
>
> is guilty. As far as I can see, the prefix-decrement should be a postfix,
> thus SourceLine[i--]. Now the result is as expected:
>
> Hallo........Tab........Tab........X
> Hallo........Tab........Tab........X
>
> Now, splitting up the declaration statement and keeping indentation, as
> Rewriter::InsertText(..indentNewLines=true) does, works well.
>
> 3. Are there any tests for TextDiagnostic.cpp? I could find one.
>
>
>
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