Fix errors and warnings from g++-4.4.1

Several additional warnings and some new errors occur when trying to compile OSL using g++-4.4.1.

Errors were due to:
- header rearrangements which cause strcmp() and exit() to be unavaliable without additional includes
- strchr (const char*, char) returns const char*

The warnings are various:
- hash_map is deprecated.  The obvious alternative is to use unordered_map from boost, but it's only avaliable after boost-1.36, so not sure if my fix will work at SPI :-/
- failing to check the return value of fgets()
- a probable operator precedence bug - && has higher precedence than || and gcc warns about a suspicious usage (hopefully I guessed right about the intention here!)
- a dangling else ambiguity (not a bug, just suspicious)
- warnings about uninitialized values

[blair, 2010-01-24 08:26:12]

On Jan 23, 2010, at 9:01 PM, chris42f@gmail.com wrote:

> Reviewers: osl-dev_googlegroups.com,
> 
> Description:
> Several additional warnings and some new errors occur when trying to
> compile OSL using g++-4.4.1.
> 
> Errors were due to:
> - header rearrangements which cause strcmp() and exit() to be
> unavaliable without additional includes
> - strchr (const char*, char) returns const char*
> 
> The warnings are various:
> - hash_map is deprecated.  The obvious alternative is to use
> unordered_map from boost, but it's only avaliable after boost-1.36, so
> not sure if my fix will work at SPI :-/

You could do what Google Protocol Buffers does and determine which hash map to
use at configure time.  It works with g++ 3.4.x all the way up to 4.4.x.  See
the m4 file at:

http://code.google.com/p/protobuf/source/browse/trunk/m4/stl_hash.m4

Protocol Buffers has a new BSD license so this could be copied straight from
them.

Running configure on my Ubuntu Karmic system with g++ 4.4.1 shows 

checking the location of hash_map... <tr1/unordered_map>

Regards,
Blair

[Chris Foster, 2010-01-24 09:28:31]

On 2010/01/24 08:26:12, blair wrote:
> You could do what Google Protocol Buffers does and determine which hash map to
> use at configure time.  It works with g++ 3.4.x all the way up to 4.4.x.  See
> the m4 file at:
> 
> http://code.google.com/p/protobuf/source/browse/trunk/m4/stl_hash.m4

IMHO this seems to be a bit of overkill, and my preferred option would be just
to specify that >=boost-1.36 was necessary.  However I know that may not be an
option for everyone so I'll let the OSL core developers chime in.  What's the
story guys?

I'll note that using hash_map *does* compile with g++-4.4.1, but not without
warnings (and hence doesn't compile when using -Werror which is turned on by
default in the build scripts).

> Protocol Buffers has a new BSD license so this could be copied straight from
> them.

The M4 would have to be converted to cmake, but it's good to see all the
potential places which hash_map may reside.  Gosh there's a lot!