Inline true, false, and unit

Motivation and Context

This fixes a Michelson code clarity issue noticed by an auditor at Inference.

The stdlib declarations for true, false and unit accidentally do not get the usual auto-inlining treatment for stdlib declarations, because (as noticed by @er433) they are actually represented as irrefutable pattern declarations at this stage (!)

This leads to slightly strange Michelson code, where PUSH bool True happens at the beginning of the code and then DUP n is used for each occurrence of true.

Technically, for true and false this will usually be an optimization, because there are no TRUE or FALSE instructions and DUP n will usually be 4 bytes while PUSH bool True is 6 bytes. But:

1. It is such a minor optimization that Michelson code clarity seems more important
2. Users can implement the optimization themselves in the usual way if desired: let shared_true = true

Here I fix the problem by just manually marking these declarations with [@inline]...

Description

Inline true, false, and unit, slightly improving clarity of generated Michelson code.

Component

• compiler
• website
• webide
• vscode-plugin
• debugger

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Performance improvement (non-breaking change that improves performance)
• None (change with no changelog)

Changelog

Checklist:

• Changes follow the existing coding style (use dune @fmt to check).
• Tests for the changes have been added (for bug fixes / feature).
• Documentation has been updated.
• Changelog description has been added (if appropriate).
• Start titles under ## Changelog section with #### (if appropriate).
• There is no image or uploaded file in changelog
• Examples in changed behaviour have been added to the changelog (for breaking change / feature).