The current wording can be read as implying that the result of a call
to a pure function does not depend on the context, which is incorrect.
The pragma only guarantees the absence of side effects of such a call.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* doc/gnat_rm/implementation_defined_pragmas.rst (Pure_Function):
	Fix ambiguous wording about context dependence.
	* gnat_rm.texi: Regenerate.