Expand set of errors caught in set_context(). Some new errors, some
old error messages changed for consistency.
Fixed error checking in generator expression code. The first set of
tests were impossible condition given the grammar. In general, the
ast code uses REQ() for those sanity checks.
Fix some error handling for augmented assignments. As comments in the
code explain, set_context() ought to work here, but I got unexpected
crashes when I tried it. Should come back to this.
Add note to Grammar that yield expression is a special case.
Add doctest cases for SyntaxErrors raised by ast.c.
Squash new warnings from VC 7.1 about mixing signed and
unsigned types in comparisons. I can see why `len` was
changed to size_t here, but don't see why `i` was also
changed. Change `i` back to int.
If a line had multiple semi-colons and ended with a semi-colon, we would
loop too many times and access a NULL node. Exit the loop early if
there are no more children.
This change implements a new bytecode compiler, based on a
transformation of the parse tree to an abstract syntax defined in
Parser/Python.asdl.
The compiler implementation is not complete, but it is in stable
enough shape to run the entire test suite excepting two disabled
tests.
