confusing messages from clang

[Dimitry Andric]

On 20 Feb 2016, at 08:33, Alex Denisov <1101.debian at gmail.com> wrote:
>> On 20 Feb 2016, at 01:57, Steve Kargl <sgk at troutmask.apl.washington.edu> wrote:
>> 
>> If anyone is interesting fixing FreeBSD's C compiler, it
>> would be appreciated.
...
>> foo.c:21:1: error: use of undeclared identifier 'corrupt'; did you mean 'crypt'?
>> corrupt:
>> ^~~~~~~
>> crypt
>> /usr/include/unistd.h:450:7: note: 'crypt' declared here
>> char    *crypt(const char *, const char *);
>>        ^
>> foo.c:21:8: error: expected ';' after return statement
>> corrupt:
>>      ^
>>      ;
>> foo.c:14:12: error: use of undeclared label 'corrupt'
>>     goto corrupt;
>>          ^
...
> I’ve submitted the bug to LLVM’s bugzilla: https://llvm.org/bugs/show_bug.cgi?id=26678
> 
> Also, it looks like OS agnostic. At least I see the same behaviour on OSX as well.

Yes, the messages could definitely be improved.  But for a compiler, it
is sometimes hard to guess the 'intent' of the code, though. :)

Note that gcc (I used 6.0 from ports) gives similarly confused messages:

foo.c: In function 'foo':
foo.c:21:1: error: 'corrupt' undeclared (first use in this function)
 corrupt:
 ^~~~~~~
foo.c:21:1: note: each undeclared identifier is reported only once for each function it appears in
foo.c:21:1: warning: 'return' with a value, in function returning void
foo.c:5:1: note: declared here
 foo(int i)
 ^~~
foo.c:21:8: error: expected ';' before ':' token
 corrupt:
        ^
foo.c:14:6: error: label 'corrupt' used but not defined
      goto corrupt;
      ^~~~

In gcc's case, it appears to read the statement as "return corrupt:",
causing it to first complain about the undeclared identifier, and then
about a missing semicolon.  Later, the label is of course still not
defined, so it complains again.

-Dimitry

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