Input files starting with a hyphen ('-') are not supported

[wwp]

$ xxdiff -- -file1 -file2
The command-line is correct (provided that -file1 and -file2 work), but this will fail because xxdiff builds a diff command-line without inserting -- before input file names.

A quick workaround is to apply this:

diff --git a/src/builderFiles2.cpp b/src/builderFiles2.cpp
index 5ed5fa3..e11c780 100644
--- a/src/builderFiles2.cpp
+++ b/src/builderFiles2.cpp
@@ -206,6 +206,7 @@ std::unique_ptr<XxDiffs> XxBuilderFiles2::process(
    }

    QStringList filenames;
+   filenames.append( "--" );
    filenames.append( buffer1.getName() );
    filenames.append( buffer2.getName() );
    QStringList out_args;
diff --git a/src/builderFiles3.cpp b/src/builderFiles3.cpp
index 5a2558c..0df98d1 100644
--- a/src/builderFiles3.cpp
+++ b/src/builderFiles3.cpp
@@ -432,6 +432,7 @@ std::unique_ptr<XxDiffs> XxBuilderFiles3::process(
    }

    QStringList filenames;
+   filenames.append( "--" );
    filenames.append( buffer1.getName() );
    filenames.append( buffer2.getName() );
    filenames.append( buffer3.getName() );

but I'm sure there are better ways to do it.

[blais]

How can we be certain that all diff programs support this?

[wwp]

@blais what are we supposed to support exactly?

I'd say that we could detect if '--' has been passed as a parameter to xxdiff, and if so, pass it through to diff calls, that even makes sense because when one uses input filenames which starts with a '-', it has to use '--' anyway to make it xxdiff consider them as input filenames.

That consideration being valid on GNU/Linux (GNU diff), macOS (BSD diff), SunOS 5+, cygwin/mingw/msys (GNU diff) at least (where I could test on), not with Aix 7.1's default diff (sorry I don't have acces to more recent Aix), where '--' is used. I guess that where diff does not support '--', it's even impossible to use filenames which start with a '-' in general.

[blais]

The ideal solution would have xxdiff allow a command line to be specified instead of just a program.

One of the issues with your proposal is that it might break some current users that have custom scripts. (This is the first time this comes up in over twenty years.)

Can't you just create a wrapper around diff for your use case?