1. 16 1月, 2018 1 次提交
    • E
      maint: Fix macros with broken 'do/while(0); ' usage · 2562755e
      Eric Blake 提交于
      The point of writing a macro embedded in a 'do { ... } while (0)'
      loop (particularly if the macro has multiple statements or would
      otherwise end with an 'if' statement) is so that the macro can be
      used as a drop-in statement with the caller supplying the
      trailing ';'.  Although our coding style frowns on brace-less 'if':
        if (cond)
          statement;
        else
          something else;
      that is the classic case where failure to use do/while(0) wrapping
      would cause the 'else' to pair with any embedded 'if' in the macro
      rather than the intended outer 'if'.  But conversely, if the macro
      includes an embedded ';', then the same brace-less coding style
      would now have two statements, making the 'else' a syntax error
      rather than pairing with the outer 'if'.  Thus, even though our
      coding style with required braces is not impacted, ending a macro
      with ';' makes our code harder to port to projects that use
      brace-less styles.
      
      The change should have no semantic impact.  I was not able to
      fully compile-test all of the changes (as some of them are
      examples of the ugly bit-rotting debug print statements that are
      completely elided by default, and I didn't want to recompile
      with the necessary -D witnesses - cleaning those up is left as a
      bite-sized task for another day); I did, however, audit that for
      all files touched, all callers of the changed macros DID supply
      a trailing ';' at the callsite, and did not appear to be used
      as part of a brace-less conditional.
      
      Found mechanically via: $ git grep -B1 'while (0);' | grep -A1 \\\\
      Signed-off-by: NEric Blake <eblake@redhat.com>
      Acked-by: NCornelia Huck <cohuck@redhat.com>
      Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
      Acked-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
      Message-Id: <20171201232433.25193-7-eblake@redhat.com>
      Reviewed-by: NJuan Quintela <quintela@redhat.com>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      2562755e
  2. 14 6月, 2016 1 次提交