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Re: progmodes/project.el and search paths

From: Eric Ludlam
Subject: Re: progmodes/project.el and search paths
Date: Fri, 14 Aug 2015 20:48:03 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0

On 08/14/2015 06:30 PM, Dmitry Gutov wrote:
On 08/14/2015 02:52 PM, Eric Ludlam wrote:

2) Parsers don't check types, etc as they go, and are flexible about the
symbols they accept.

This means you can get irrational tags.  This is for a combination of
handling incomplete code, speed (less to do) and because most folks just
go an run their compiler at some point anyway.

Doesn't that mean that code completion at the end of a chain of calls can be inaccurate (with e.g. lots of false positives), even if code is otherwise valid?

While the parser generally ignores data types, it does record the declarations. When smart completion is invoked, only the types currently relevant are resolved in order to make the completions accurate. Thus:

Parsing phase: Just record the data as declared, don't check.

Completion phase: Look up data types as needed for symbols in the completion string.

If point of fact, Semantic's tagging parser doesn't parse the bodies of functions, and just skips over them. The body is only parsed if a completion is needed since the symbols within are locally scoped and don't affect other tags.

On a side note, I've had a lot of complaints that completion was too pedantic, and if it can't find a pedantic answer, perhaps it could let loose a little and find a vaguely close answer.

In summary; Semantic can extract useful data out of pretty badly trashed
code, and track your changes while you edit in a robust way.

It seems I stand corrected, thanks. However, it would be interesting to do a comparison on some real file, against a widely used compiler, such as Clang.

That would be interesting. What would the goal be? There are lots of things Semantic doesn't do, nor was intended for. Like many Emacs tools, the Semantic parser is a bit liberal in the assumptions it makes to get a good enough answer.


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