bash completion for argument defined with value_name should complete with file names

[jzinn]

Ripgrep has a -g option that could use some improved Bash completion. Please see

• bash completion for -g glob BurntSushi/ripgrep#792

Rust Version

$ rustc -V
rustc 1.25.0-nightly (b8398d947 2018-02-11)

Affected Version of clap

$ grep clap ripgrep/Cargo.lock
name = "clap"
 "clap 2.29.4 (registry+https://github.com/rust-lang/crates.io-index)",
"checksum clap 2.29.4 (registry+https://github.com/rust-lang/crates.io-index)" = "7b8f59bcebcfe4269b09f71dab0da15b355c75916a8f975d3876ce81561893ee"

Expected Behavior Summary

Either do nothing:

touch Foo.txt
rg -g Fo<tab>  # hit <tab> to initiate completion
rg -g Fo       # after completion

or complete with file names:

touch Foo.txt
rg -g Fo<tab>  # hit <tab> to initiate completion
rg -g Foo.txt  # after completion

Additionally, the Ripgrep -g option allows a leading ! to indicate negation. If Clap can support this, then an example would be

mkdir vendor
rg -g "!vend<tab>  # hit <tab> to initiate completion
rg -g "!vendor"/   # after completion

Actual Behavior Summary

Currently the typed in value is erased and replaced with <GLOB>...:

touch Foo.txt
rg -g Fo<tab>    # hit <tab> to initiate completion
rg -g <GLOB>...  # after completion

Steps to Reproduce the issue

See above.

Sample Code or Link to Sample Code

I could easily be wrong, but Ripgrep seems to instantiate a clap-rs Arg using something similar to:

Arg::with_name("glob")
    .long("glob")
    .value_name("GLOB")
    .takes_value(true)
    .number_of_values(1)
    .short("g")
    .help("Include or exclude files.")
    .long_help("Include or exclude files and ...")
    .multiple(true)
    .allow_hyphen_values(true)
    ;

It seems that value_name is used in the completion (<GLOB>...) instead of file names.

Debug output

[kbknapp]

Thanks! I'll take a look at this tomorrow and see if I can get a patch in to just fall back to file completion in all cases.

[jzinn]

As an aside, with the current behavior it seems that these options

.takes_value(true)
.number_of_values(1)
.multiple(true)

should not result in <GLOB>..., because the ... indicates that repetition is possible. However, repetition is not allowed in this case because of the call number_of_values(1).

[BurntSushi]

@jzinn That refers to the number of values per use of the flag, and not the number of times the flag can be used. That is, they are orthogonal options. :)

[kbknapp]

v2.30.0 is published