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Support Null Tag #4151

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hirooih opened this issue Dec 7, 2024 · 8 comments
Closed

Support Null Tag #4151

hirooih opened this issue Dec 7, 2024 · 8 comments
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@masatake
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next-release
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6.2

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@hirooih
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hirooih commented Dec 7, 2024

Some languages (ex. (System)Verilog #4129) supports a Null Tag (a tag whose name field is "\0").
The current makeTagEntry() ignores or warns it.
@hirooih
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hirooih commented Dec 8, 2024

Here is my comment to #4129 (comment)

Could you open a separate issue to support a null tag?

I've opened this issue.

I have two concerns:

  1. The current implementation of libreadtags skips lines with empty names.
    ...
    The line comparing with '\0' comes from the exuberant ctags.
    Our ancestors assume an empty tag is invalid.

I don't concerns this. The u-ctags has many more features than the exuberant ctags. Emiting more tags is not an issue. As you wrote, it just ignores a Null Tag.

I rather fear that other client tools may crash with null tags. So we may need a command line option to disable Null Tags.

  1. the other file formats
    u-ctags supports etags and xref. Do they consider null tags?

As far as I read Xref output man page it can express a Null Tag.

Again as I wrote on #4129 (comment)

Even if it were not currently supported, it would not be worth the bother to support it, I think.

This is my position.

@masatake masatake self-assigned this Dec 8, 2024
masatake added a commit to masatake/ctags that referenced this issue Dec 8, 2024
@masatake
main: add nulltag/0, a new extra
a9b0a15 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating ctags(1),
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
masatake added a commit to masatake/ctags that referenced this issue Dec 8, 2024
@masatake
main: add nulltag/0, a new extra
1ece264 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating ctags(1),
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
masatake added a commit to masatake/ctags that referenced this issue Dec 8, 2024
@masatake
main: add nulltag/0, a new extra
a47b03c 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating ctags(1),
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
masatake added a commit to masatake/ctags that referenced this issue Dec 8, 2024
@masatake
main: add nulltag/0, a new extra
9447926 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating ctags(1),
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
masatake added a commit to masatake/ctags that referenced this issue Dec 8, 2024
@masatake
main: add nulltag/0, a new extra
5b2636b 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating ctags(1),
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
masatake added a commit to masatake/ctags that referenced this issue Dec 8, 2024
@masatake
main: add nulltag/0, a new extra
0d23879 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating ctags(1),
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
@cousteaulecommandant
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I've written a few examples in JSON, Tcl, and SystemVerilog featuring null tags, in case you're interested.

Interestingly, tags that are inside a "namespace" that has a null identifier are displayed in the hierarchy as such, even if the identifier won't.
For example, this JSON code:

{"": {"": {"a": {"": {"": {"b": {"": {"": {"c": 0}}}}}}}}}

outputs

a	[...]	o
b	[...]	o	object:a..
c	[...]	n	object:a...b..

(the leading blank containers are ignored, but the intermediate ones are preserved - note that it says c is in a...b.. and not a.b)

(Attached: null-tags.r.tar.gz)

@jafl
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jafl commented Dec 10, 2024

Please make a PR for the tests that you attached.

@masatake masatake added this to the 6.2 milestone Dec 11, 2024
@cousteaulecommandant
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cousteaulecommandant commented Dec 13, 2024 •
edited
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Please make a PR for the tests that you attached.

I can do that but it'll cause CI tests to fail ("unexpected exit state"), so I first need to figure out how to exclude those tests from CI.
I'll put something together.

masatake added a commit to masatake/ctags that referenced this issue Dec 13, 2024
@masatake
main: add nulltag/0, a new extra
a4eeb7f 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating ctags(1),
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"
- update units.py supporting nulltags

Signed-off-by: Masatake YAMATO <[email protected]>
@masatake
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@cousteaulecommandant You can ignore failures.

What we need are pairs of input and expected output.
null-tags.r.tar.gz is not suitable for my git workflow.

Thank you so much for your attention and participation.

masatake added a commit to masatake/ctags that referenced this issue Dec 14, 2024
@masatake
main: add nulltag/z, a new extra
a64bfc5 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
@cousteaulecommandant
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Should I modify expected.tags manually to reflect what I expect, including empty tags? Or just use what ctags outputs?

@masatake
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Yes, please modify expected.tags manually to reflect what you expect.

masatake added a commit to masatake/ctags that referenced this issue Dec 14, 2024
@masatake
main: add nulltag/z, a new extra
73812f7 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
masatake added a commit to masatake/ctags that referenced this issue Dec 14, 2024
@masatake
main: add nulltag/z, a new extra
2c4734e 
Close universal-ctags#4151.

Consider a parser attempting to emit a null tag, a tag whose
name is the empty string '\0'.

Original Behavior:

    It warns "ignoring null tag..." if both parserDefinition::allowNullTag and
    tagEntryInfo::allowNullTag are unset.

    It does not warn if either parserDefinition::allowNullTag or
    tagEntryInfo::allowNullTag is set.

    It does not emit the null tag, even if allowNullTag is set.

With This Change: The code now emits the null tag if:

    Either parserDefinition::allowNullTag or tagEntryInfo::allowNullTag
    is set, and

    The --extras=+0 (or --extras=+{nulltag}) option is specified.

TODO:
- versioning
- updating the hacking guide
- make readtags warn "unsupported" if it finds "!_TAG_FIELD_DESCRIPTION"

Signed-off-by: Masatake YAMATO <[email protected]>
Open
@cousteaulecommandant
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OK done, see #4157 :)
I have noticed that the Tcl parser doesn't seem to handle quoted/braced proc names, so neither proc {} {} {} nor proc "" {} {} will work (and neither does proc {foo} {} {} nor proc "bar" {} {} anyway), so maybe I should get rid of the Tcl test.

@masatake masatake mentioned this issue Dec 20, 2024
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