Reserved identifiers used as local variables

[gilles-peskine-arm]

Identifiers starting with underscore and a capital letter, or with two underscore, are reserved everywhere in the C language. (Identifiers starting with an underscore and a lowercase letter are only reserved at file scope.) The library uses some reserved identifiers.

Here's a search that weeds out most positives:

grep -P '^(?!#| \*| *!?\(? *defined\(| *(__asm|__attribute__|__GNUC__)).*\b(?!__FILE__|__LINE__)_[A-Z_]' library/*.c tests/suites/*.function programs/*/*.c

The true positives are all in bignum.c: _B variable in several mbedtls_mpi_xxx_int functions and _RR argument in mbedtls_mpi_exp_mod.