On May 15, 2012, at 4:50 PM, Terry Long wrote:
> Attached is a new version of the patch for review.
> I have removed all of the textual parsing and replaced it with code that
> finds a DeclRefExpr if it exists.
> Unfortunately, this will catch a lot less cases, but at least it will catch
> some common ones and display them nicely.
I like this patch a lot, and I think it's a good trade-off between complexity
and functionality. Thank you! Committed as r156904.
- Doug
> -Terry
>
> <PR9243v2.patch>
>
> Am 15.05.2012 um 18:41 schrieb Douglas Gregor:
>
>>
>> On May 15, 2012, at 3:28 PM, Terry Long <[email protected]> wrote:
>>
>>>
>>> Am 15.05.2012 um 16:09 schrieb Douglas Gregor
>>>>
>>>>
>>>> I'm a bit uncomfortable with the textual approach here. Why not analyze
>>>> the expressions to check whether they are references to named
>>>> declarations, and use those names in the diagnostic? It won't catch some
>>>> macro cases, but it's far simpler.
>>>
>>> I was also uncomfortable with the textual approach, and in fact I first
>>> tried seeing if the case expression was a DeclRefExpr that refers to a
>>> valid NamedDecl. The problem I found with that approach was that it was not
>>> catching very many situations. Doing it that way only works for enums as
>>> far as I can tell. Macros, const ints, case overflows, casting, and more
>>> complicated expressions (like "case 2+2") are not DeclRefExprs, and I don't
>>> see any obvious way to grab the necessary diagnostic info without using a
>>> textual approach.
>>
>>
>> You can look through implicit conversions (e.g., promotions) and parentheses
>> to find the underlying expression. We'll get a DeclRefExpr for enumerators
>> and variables that are constant ("const int x = 17;"), which are presumably
>> the common cases. We won't get macros, of course, but we might not want to:
>> it's probably more useful to show the value we get when the macro is
>> expanded, and let the macro-substitution backtrace show how we got there.
>>
>> - Doug
>
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