feat(transpiler): transpile gno standard libraries

[thehowl]

Merge order:

1. feat(stdlibs): remove support for linkedType in native bindings #1700
2. feat(gno.land): add go type checking to keeper + tx simulation in gnokey #1702
3. feat(transpiler): transpile gno standard libraries #1695 (this one!) -- review earlier ones first, if they're still open!

This PR modifies the Gno transpiler (fka precompiler) to use Gno's standard libraries rather than Go's when performing transpilation. This creates the necessity to transpile Gno standard libraries, and as such support their native bindings. And it removes the necessity for a package like stdshim, and a mechanism like stdlibWhitelist.

• Fixes stdlibWhitelist is not kept in sync with new stdlib packages #668. Fixes [GnoVM] Whitelist deployment paths instead of import paths #1865.
• Resolves Discussion: stdlibs/stdshim/*.gno #892.
• Part of [META] improved native bindings #814.
• Makes META - splitting and refactoring std #1475 / Making the std package API more user-friendly #1576 possible without using hacks like stdshim.

cc/ @leohhhn @tbruyelle, as this relates to your work

Why?

• This PR enables us to perform Go type-checking across the board, and not use Go's standard libraries in transpiled code. This enables us to properly support our own standard libraries, such as std but any others we might want or need.
• It also paves the way further to go full circle, and have Gno code be transpiled to Go, and then have "compilable" gno code

Summary of changes

• The transpiler has been thoroughly refactored.
  • The biggest change is described above: instead of maintaing the import paths like "strconv" and "math" the same (so using Gno's stdlibs in Gno, and Go's in Go), the import paths for standard libraries is now also updated to point to the Gno standard libraries.
  • Native functions are handled by removing their definitions when transpiling, and changing their call expressions where appropriate. This links the transpiled code directly to their native counterparts.
  • This removes the necessity for stdlibWhitelist.
  • As a consequence, stdshim is no longer needed and has been removed.
  • Test files are still not "strictly checked": they may reference stdlibs with no matching source, and will not be tested when running with --gobuild. This is because packages like fmt have no representation in Gno code; they only exist as injections in tests/imports.go. I'll fix this eventually :)
• The CLI (gno transpile) has been changed to reflect the above changes.
  • Flag --skip-fmt has been removed (the result of transpile is always formatted, anyway), and --gofmt-binary too, obviously. gno transpile does not perform validation, but will gladly provide helpful validation with the --gobuild flag.
  • There is another PR that adds type checking in gno lint, without needing to run through the transpilation step first: feat(cmd/gno): perform type checking when calling linter #1730
  • It now works by default by looking at "packages" rather than individual files. This is necessary so that when performing transpile on the examples directory, we can skip those where the gno.mod marks the module as draft. These modules make use of packages like "fmt", which because they don't have an underlying gno/go source, cannot be transpiled.
  • Running with -gobuild now handles more errors correctly; ie., all errors not previously captured by the errorRe which only matches those pertaining to a specific file/line.
  • gnoFilesFromArgs was unused and as such deleted
• gnomod's behaviour was slightly changed.
  • I am of the opinion that gno mod download should not precompile what it downloads; especially to gather the dependencies it has. I've changed it so that it does a OnlyImports parse of the file it downloads to fetch additional dependencies

Misc:

• Makefile now contains a recipe to calculate the coverage for gnovm/cmd/gno, and also view it via the HTML interface. This is needed as it has a few extra steps (which @gfanton already previously added in the CI).
• Realms r/demo/art/gnoface and r/x/manfred_outfmt have been marked as draft, as they depend on packages which are not actually present in the Gno standard libraries.
  • The transpiler now ignores draft packages by default.
• ReadMemPackage now also considers Go files. This is meant to have on-chain the code for standard libraries like std which have native bindings. We still exclude Go code if it's not in a standard library.
• //go:build constraints have been removed from standard libraries, as go files can only have one and we already add our own when transpiling

Further improvements

after this PR

• Scope understanding in transpiler (so call expressions are not incorrectly rewritten)
• Correctly transpile gno.mod

[zivkovicmilos]

@thehowl can you merge in master?

[thehowl]

@zivkovicmilos done

[ajnavarro]

I left some nits, apart from them, LGTM.

[zivkovicmilos]

Overall looks good 💯

I've left some comments and nits. We're good to merge after resolving 🚀

[tbruyelle]

@thehowl Sorry for coming after the merge, but do you consider setting this env var directly when go transpile -gobuild is invoked ?
Because else the error relating to lack of go.mod will pop up each time this command is invoked with a directory argument (which is a quite common situation when using gnols).

[thehowl]

It's an idea. I guess more in general the thing is that we shouldn't use go build; because even if GO111MODULE=off, then it will try to use go's old depedency system.

This could eventually be fixed by #1730, which makes it so we don't need go build to get typecheck errors. I haven't managed to keep up with that one much, dealing with other priorities, alas. But I want to try to maybe wrap it up this week, before I go on holiday.

[tbruyelle]

Indeed, it would be even better without using go build.