[cfe-commits] [PATCH][PR11329][v4] Generalize -Wempty-body: warn when statement body is empty

[Dmitri Gribenko]

Hello,

Attached is a patch that implements enhancement proposed in PR11329.

Thanks to the reviewers' comments, I've implemented the following
heuristic.  For and while with null statement as a body should be
followed by a CompoundStmt in order to emit a warning.

But applying only the heuristic explained above limits the warning to
for(...);{...} cases.  The second proposed heuristic is to emit a
warning also if for/while have less indentation than the next
statement, e. g.:

    for (int i = 0; i < n; i++)
        a(i);

Applying only the first heuristic silences all warnings in chromium.
Applying the second adds false positives in the following cases:
<TAB>for (...);
<8 spaces>foo();

and:
<INDENT>for (...);
<empty lines or comments...>
<MORE INDENT for some reason>foo();

We can silence the second case if we check that foo(); is on the next line.

All in all:
+ 3 warnings in chromium
+ 1 warning in llvm (can be silenced as explained above)

Dmitri

-- 
main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
(j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/
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