To search for an erroneous pattern like this:
{{{
for (i = 0; i < n; i++) {}
...
if (i > n) ...
}}}
This is wrong because at the end of the loop i equals n and cannot be greater than n. To match this:
{{{
gres -A40 "^ for \(" \
"for \( (@V) = @d ; \1 < @d ; \1 \+\+ \)
    \{.8.\}
@n
if \( \1 > \3 \)" | less
}}}
The first string is used to get the git grep query. To see what is queried for see {{{bli2 "^ for \("}}}.

@V is translated to {{{[[:alpha:]_]+[[:alnum:]_]*}}}, which matches a local variable. @d matches any number and contains parentheses, that's why we have to use \3, as a back-reference to match the second @d. 

This currently results after about 10 seconds in a match:
{{{
---[ vi drivers/mmc/host/s3cmci.c +1209 ]---
	/* Set clock */
	for (mci_psc = 0; mci_psc < 255; mci_psc++) {
		...
	}

	if (mci_psc > 255)
		mci_psc = 255;
	...
}}}
Quite harmless so I left it.

More advanced examples can be found here [wiki:roelkluin/gres_tests/loops gres_tests/loops]