If you are curious, we could now try to find out what precisely goes
wrong. The procedure would be this

* after each step, check whether the problem still occurs

a) resolve the includes manually, then strip everything that isn't
needed. This could start with fastsearch.h and find.h; then
remove everything that refers to Python.h (i.e. replace Py_ssize_t
with ssize_t, Py_LOCAL_INLINE with static inline, and so on), then
remove Python.h

b) try simplifying the code, e.g. replace str_len and sub_len with
their (constant) values, drop the sub_len == 0 block, and so on.

c) when further simplification is not possible (while keeping the
actual error), start looking at the assembler code.

Alternatively, sent this or some further-simplified version to Intel
(assuming they have some kind of bug-reporting channel for icc). With my
compiler-vendor's hat on, I'd like to get a test case for bad code
generation that comes as a single file, with no includes; for gcc, the
request is to submit preprocessor output.

Assuming this is too much effort, I'll close this as "won't fix - third
party".