[cfe-commits] r163588 - in /cfe/trunk: lib/Lex/PPDirectives.cpp test/Index/c-index-getCursor-pp.c

[Richard Smith]

On Tue, Sep 18, 2012 at 10:23 AM, Argyrios Kyrtzidis <kyrtzidis at apple.com>wrote:

> On Sep 17, 2012, at 4:50 PM, Richard Smith <richard at metafoo.co.uk> wrote:
>
> On Mon, Sep 17, 2012 at 4:04 PM, James Dennett <jdennett at google.com>wrote:
>
>> On Mon, Sep 17, 2012 at 3:04 PM, Argyrios Kyrtzidis <kyrtzidis at apple.com>
>> wrote:
>> >
>> > On Sep 17, 2012, at 2:38 PM, James Dennett <jdennett at googlers.com>
>> wrote:
>> >
>> >> On Mon, Sep 17, 2012 at 2:22 PM, Argyrios Kyrtzidis <
>> kyrtzidis at apple.com> wrote:
>> >>> On Sep 17, 2012, at 12:44 PM, James Dennett <jdennett at googlers.com>
>> wrote:
>> >>>
>> >>>> On Mon, Sep 10, 2012 at 7:17 PM, Argyrios Kyrtzidis <
>> akyrtzi at gmail.com> wrote:
>> >>>>> Author: akirtzidis
>> >>>>> Date: Mon Sep 10 21:17:21 2012
>> >>>>> New Revision: 163588
>> >>>>>
>> >>>>> URL: http://llvm.org/viewvc/llvm-project?rev=163588&view=rev
>> >>>>> Log:
>> >>>>> [libclang] Fix getting a cursor inside an angled #include directive.
>> >>>>>
>> >>>>> Fixed by pointing the end location of the preprocessed entity for
>> the #include
>> >>>>> at the closing '>', instead of the start of '<'.
>> >>>>>
>> >>>>> rdar://11113134
>> >>>>>
>> >>>>> Modified:
>> >>>>>   cfe/trunk/lib/Lex/PPDirectives.cpp
>> >>>>>   cfe/trunk/test/Index/c-index-getCursor-pp.c
>> >>>>>
>> >>>>> Modified: cfe/trunk/lib/Lex/PPDirectives.cpp
>> >>>>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/PPDirectives.cpp?rev=163588&r1=163587&r2=163588&view=diff
>> >>>>>
>> ==============================================================================
>> >>>>> --- cfe/trunk/lib/Lex/PPDirectives.cpp (original)
>> >>>>> +++ cfe/trunk/lib/Lex/PPDirectives.cpp Mon Sep 10 21:17:21 2012
>> >>>>> @@ -1296,6 +1296,9 @@
>> >>>>>  case tok::string_literal:
>> >>>>>    Filename = getSpelling(FilenameTok, FilenameBuffer);
>> >>>>>    End = FilenameTok.getLocation();
>> >>>>> +    // For an angled include, point the end location at the
>> closing '>'.
>> >>>>> +    if (FilenameTok.is(tok::angle_string_literal))
>> >>>>> +      End = End.getLocWithOffset(Filename.size()-1);
>> >>>>>    CharEnd = End.getLocWithOffset(Filename.size());
>> >>>>>    break;
>> >>>>>
>> >>>>>
>> >>>>> Modified: cfe/trunk/test/Index/c-index-getCursor-pp.c
>> >>>>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Index/c-index-getCursor-pp.c?rev=163588&r1=163587&r2=163588&view=diff
>> >>>>>
>> ==============================================================================
>> >>>>> --- cfe/trunk/test/Index/c-index-getCursor-pp.c (original)
>> >>>>> +++ cfe/trunk/test/Index/c-index-getCursor-pp.c Mon Sep 10 21:17:21
>> 2012
>> >>>>> @@ -15,6 +15,8 @@
>> >>>>>
>> >>>>> const char *fname = __FILE__;
>> >>>>>
>> >>>>> +#include <a.h>
>> >>>>> +
>> >>>>> // RUN: c-index-test -cursor-at=%s:1:11 -I%S/Inputs %s | FileCheck
>> -check-prefix=CHECK-1 %s
>> >>>>> // CHECK-1: macro definition=OBSCURE
>> >>>>> // RUN: c-index-test -cursor-at=%s:2:14 -I%S/Inputs %s | FileCheck
>> -check-prefix=CHECK-2 %s
>> >>>>> @@ -31,6 +33,8 @@
>> >>>>> // CHECK-7: macro expansion=B:12:9
>> >>>>> // RUN: c-index-test -cursor-at=%s:16:25 -I%S/Inputs %s | FileCheck
>> -check-prefix=CHECK-8 %s
>> >>>>> // CHECK-8: macro expansion=__FILE__
>> >>>>> +// RUN: c-index-test -cursor-at=%s:18:12 -I%S/Inputs %s |
>> FileCheck -check-prefix=CHECK-9 %s
>> >>>>> +// CHECK-9: inclusion directive=a.h
>> >>>>>
>> >>>>> // Same tests, but with "editing" optimizations
>> >>>>> // RUN: env CINDEXTEST_EDITING=1 c-index-test -cursor-at=%s:1:11
>> -I%S/Inputs %s | FileCheck -check-prefix=CHECK-1 %s
>> >>>>
>> >>>> This change broke clients that implement
>> >>>> PPCallbacks::InclusionDirective, which now receive the location of
>> the
>> >>>> closing '>' rather than the location of the token that they're
>> >>>> expecting based on the spec:
>> >>>> /// \param EndLoc The location of the last token within the
>> >>>> inclusion
>> >>>> /// directive.
>> >>>> The last (preprocessing) token is the whole of <filename>, of type
>> >>>> tok::angle_string_literal.
>> >>>>
>> >>>> Could we consider reverting this change and finding an alternative
>> way
>> >>>> to fix libclang without breaking/changing the lower-level interface?
>> >>>
>> >>> Hi James,
>> >>>
>> >>> This is not a high-level libclang issue.
>> >>
>> >> Apologies, I was going by the change description "[libclang] Fix
>> >> getting a cursor inside an angled #include directive.", and that the
>> >> only tests I saw included were for libclang.  (That does suggests that
>> >> we're missing tests for this in the appropriate place.)
>> >
>> > You're right, a preprocessing record unit test is also needed.
>> >
>> >>
>> >>> The preprocessing record needs to know the '>' location and depends
>> on the PPCallbacks::InclusionDirective callback. Previously this callback
>> did not provide a way to reliably get at that location.
>> >>
>> >> I'm not sure about that -- it provided a way to get there, but it was
>> >> necessary to skip over the filename.
>> >
>> > If the include filename was formed via a macro expansion then you had
>> an EndLoc pointing at '>'. So this was the situation:
>> >
>> > No macro expansions involved: EndLoc points at '<'
>> > With macro expansion: EndLoc points at '>'.
>> >
>> > The receiver had no easy way to know which case it was. With the change
>> it always pointed at '>'.
>>
>> Checking which character is at the EndLoc isn't so hard, but I take your
>> point.
>>
>> >> With your change a similar trick
>> >> is required for code wanting to get to the filename, but only for
>> >> #include <filename>, not for #include "filename".  (Why are the two
>> >> cases different?  Currently the callback returns the location of the
>> >> opening quote for the #include "name" case, and the closing one for
>> >> #include <name>.  The asymmetry seems strange.)
>> >
>> > There's an asymmetry due to how lexing would behave if you pointed at
>> the beginning of the filename, for example:
>> >
>> > #include "filename"
>> > If you point at the opening quote and start lexing you will get the
>> tok::string_literal token, the same that the preprocessor saw. Then you can
>> get at the character range of the whole filename input by checking the
>> token size.
>> >
>> > #include <filename>
>> > if you point at the opening '<' and start lexing you will get a
>> tok::less token, you need to get into the special "parsing include
>> directive" mode to receive a tok::angle_string_literal token.
>> > So just pointing at '<' will not allow you to easily lex and get the
>> character range of the filename input.
>>
>> I was assuming that you'd lex correctly, which means being in the
>> right mode to lex an include directive in this case.  I don't think it
>> matters that if you lex incorrectly that you'll get the wrong results.
>>
>> >>> I believe we still need to modify the bahavior of the
>> InclusionDirective callback and focus the discussion there.
>> >>>
>> >>> How about reverting the EndLoc adjustment but have the
>> InclusionDirective also pass the FilenameTok token so that receivers of the
>> callback can have more information for the inclusion directive (then the
>> preprocessing record can do the adjustment itself).
>> >>
>> >> That sounds good to me -- though I'm not sure if we need to pass
>> >> EndLoc if we pass the FilenameTok (possibly for cases where the
>> >> filename comes from macro expansion? I'm not all that familiar with
>> >> this code).
>> >
>> > Yes, the EndLoc is necessary because if there are macro expansions
>> involved then the FilenameTok token will be a tok::less for '<'.
>>
>> This is going to be "fun" to document thoroughly enough for clients to
>> be written based on the spec alone -- but then the quirky lexing rules
>> for this context are what they are, and Clang can't (and shouldn't)
>> completely hide them.
>
>
> In terms of getting something which is easy to explain, how about we pass
> FilenameTok, as described above, and we also pass the location of the
> terminating > or " *character* as EndLoc? Would that cover all the use
> cases?
>
>
> Not sure about pointing at the character, pointing at '>' is pointing at
> something that can be lexed raw as a token, while pointing at the ending
> quote is not.
>

You can't lex the ending character as a token in the angle_string_literal
case either. For instance, we accept (with a warning):

#include <iostream>>

If you try to lex the '>' as a token, you'll get '>>'. But I don't see why
it would be useful to lex from that position, so I don't think this matters.


> How about a minor change to your suggestion and pass the end location of
> the directive character range (just after the > or "); this is already
> calculated as the CharEnd variable.
>

Yes, I think that's an improvement. I had incorrectly recalled that a
CharRange included both the start and end character. Since it actually
excludes its end character (unlike a TokenRange!), this seems like the more
useful option. On reflection, I think my preferred option would be to ditch
FilenameTok and pass a CharSourceRange for the included entity to the
InclusionCallback.
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