Add explicit vars and enable --strict-var

[Timmmm]

This adds explicit var keywords where they were missing before, and enables the --strict-var flag to prevent us from missing them out in future. Implicit var was a mistake inherited from ASL.

[Timmmm]

Note, a lot of these vars are totally unnecessary and should be lets. In future we should go through the code and audit all vars and undefineds to make sure they are really appropriate.

@Alasdair the Sail compiler could probably benefit from a "var foo is never mutated; use let instead" warning. Or maybe even make it an error.

[github-actions[bot]]

Test Results

712 tests  ±0   712 :white_check_mark: ±0   0s :stopwatch: ±0s   6 suites ±0     0 :zzz: ±0    1 files   ±0     0 :x: ±0 

Results for commit 3d1c9ab1. ± Comparison against base commit ad8b8cb0.

:recycle: This comment has been updated with latest results.

[Alasdair]

I added the warning you suggested, but it looks like you fixed the place where it would occur already!

Warning: Unnecessary mutability model/riscv_fetch.sail:38.16-21:
38 |                PC_hi : xlenbits = PC + 2;
   |                ^---^
   | 
This variable is mutable, but it is never modified. It could be declared as immutable using 'let'.

[Timmmm]

Ha, I thought there would be more in the vector code but I guess those are all tuples where one part is modified.

[Timmmm]

@billmcspadden-riscv ok if I merge this?

[billmcspadden-riscv]

merged

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@billmcspadden-riscv https://github.com/billmcspadden-riscv ok if I merge this?

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[Alasdair]

I think most of the vector code has the following shape:

var result = undefined;
var mask = undefined;

(result, mask) = init

If it was like var (result, mask) = init it would warn on mask being unmodified I think.

[Timmmm]

Ah cool, I'll go through and change them all at some point and then hopefully we'll see the warning.