Combine the initialization, implicit conversion, and value category
conversion functions into a single function.
This substantially reduces the duplication between these steps, and
ensures that we support the same set of conversions in all these
contexts. This also fixes some issues where we would not use the proper
value representation for tuples and structs after performing implicit
conversions.
In general, LLVM's parsing of decimal integers to `APInt`s forms an
`APInt` that is 4n bits wide, where n is the length of the integer, and
the `isNegative` check only checks the high bit.
In this case, we form an `APInt` that is four bits wide, with the high
bit set, which we reject because we think it's "negative". These two
array lengths are the only ones where this happens -- if the decimal
integer value is two characters long, we form an `APInt` that is eight
bits wide but holds a value < 100, so the high bit is never set, and the
same applies for longer integers too.
An `IntegerLiteral` is never negative, so we don't need the `isNegative`
check, and in fact it only detects the n=8 and n=9 cases.
Continuing with #3070. Just a dir and file rename (mostly removing
prefixes, although for parse_tree_fuzzer and parse_tree_file_test I'm
dropping "tree" instead of "parse"). Everything in the parse dir should
be marked as a move.
Continuing along with #3070. Note this is just a file rename, with BUILD
edits; every file previously in semantics/ should show as moved (except
maybe BUILDs, which split).
Richard Smith
Jon Ross-Perkins
Geoff Romer