[GitHub] jaydoane opened a new pull request #1215: Introduce bin_opt_info erl_opts compilation option

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jaydoane opened a new pull request #1215: Introduce bin_opt_info erl_opts compilation option
URL: https://github.com/apache/couchdb/pull/1215
 
 
   
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   ## Overview
   
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        what problem it solves or how it makes things better. -->
   
   As discussed in
   http://erlang.org/doc/efficiency_guide/binaryhandling.html, the
   bin_opt_info option can have the compiler print information about
   binary optimizations. Typically, it issues warnings about code that
   can not be optimized. For example, with the option enabled, it warns
   about this line of code (among many others) like this:
   ```
   src/chttpd/src/chttpd_auth_cache.erl:183: Warning: NOT OPTIMIZED: sub binary is used or returned
   ```
   Not only should having this option enabled draw awareness to existing
   sub-optimal binary constructs, it should help developers avoid
   creating new ones.
   
   ## Testing recommendations
   
   <!-- Describe how we can test your changes.
        Does it provides any behaviour that the end users
        could notice? -->
   
   This is a compiler configuration change, so test it by running `make clean && make`. You should now see numerous warnings about failed binary optimizations such as
   ```
   /Users/jay/proj/couchdb/src/couch_replicator/src/couch_replicator_api_wrap.erl:401: Warning: INFO: matching anything else but a plain variable to the left of binary pattern will prevent delayed sub binary optimization; SUGGEST changing argument order
   /Users/jay/proj/couchdb/src/couch_replicator/src/couch_replicator_api_wrap.erl:1019: Warning: NOT OPTIMIZED: sub binary is used or returned
   ```
   
   ## Related Issues or Pull Requests
   
   <!-- If your changes affects multiple components in different
        repositories please put links to those issues or pull requests here.  -->
   
   ## Checklist
   
   - [x] Code is written and works correctly;
   - [ ] Changes are covered by tests;
   - [ ] Documentation reflects the changes;
   

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