Handles tuples (including nested tuples) in the semantic phase of the
tool chain. Does not handle tuple element access yet.
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Co-authored-by: Farzana Ahmed Siddique <fasiddique@google.com>
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
I think there's more we can do here, but this seemed like a good
checkpoint to make sure the path I'm going down is roughly what you
expected. There's one actual edit in if expression structure to match
the increased enforcement.
This follows the same structure as `if` expressions, except that no
result value is needed.
Semantics IR building for code blocks is also added. Rather than popping
all the node stack entries we push for statements within a code block,
change statements and declarations to not push themselves onto the
stack. We're not notionally performing work recursively within prior
statements, and we don't need their value for anything, so it seems
cleaner to not push them. This also allows statements and declarations
to determine what syntactic context they're in by peeking at the top of
the stack, though that's not used in this patch.
Richard Smith