main: add tinygo fix - #5992

This is mostly working now. It has some usability issues compared to regular go fix because the intersectional nature of tinygo's use of build tags. However, if applied surgically, it does work, examples follow.

More than modernising existing tinygo code, it unlocks the //go:fix inline pragma which lets us deprecate older methods and have code automatically rewriting from the forwarding stubs to newer forms. I'll include an example as well

example one

./build/tinygo fix -target pico -diff -rangeint ./src/internal/reflectlite

-for i := uintptr(0); i < size; i++ {
+for range size {

example two

./build/tinygo fix -target pico -diff -rangeint ./src/machine/usb/msc

-for i := 0; i < length; i++ {
+for i := range length {

example three

./build/tinygo fix -C ~/devel/drivers -target pico -diff -rangeint ./ssd1289

-for i := uint8(0); i < 16; i++ {
+for i := range uint8(16) {
     pin := machine.Pin(i + uint8(firstPin))
     pin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 }

example four; interface{} -> any

./build/tinygo fix -C ~/devel/drivers -target pico -diff -any ./tester

- Fatalf(f string, a ...interface{})
+ Fatalf(f string, a ...any)

#5966 adds RandomUint32 and marks the old GetRNG wrapper with //go:fix inline.

TINYGOROOT=<rename-branch-sources> ./build/tinygo fix \
  -C <caller-module> -target pico -inline -diff .

-value, err := machine.GetRNG()
+value, err := machine.RandomUint32()

The test failure is karma for fixing the tests so they actually run on windows :)

@davecheney thanks for working on fixing fix. I checked out this PR and ran the tests locally. Here are some notes edited from an automated review:

1. /... patterns under TinyGo's src find no packages. ./src/machine/..., ./src/machine/usb/..., ./src/internal/... and ./src/runtime/... all end with no packages matched. The cached GOROOT has those directories as symlinks, and go list does not follow symlinks for .... ./src/... turns into std, which fails with package net (test) imports internal/poll: build constraints exclude all Go files. The error for plain ./src also suggests ./src/.... Perhaps expand these patterns by walking $TINYGOROOT/src instead of passing them to go list, or at least change that hint?

2. The -diff output is always one hunk from the first change to the last, so unchanged lines in between show up as removed and added. For example tinygo fix -target pico -diff ./src/machine shows 83 lines of -/+ in machine_rp2_i2c.go and the whole roscRandByte function in machine_rp2_rng.go for two rangeint changes. The patch still applies, but it is hard to read. Separate hunks with 3 lines of context, like go fix -diff, might help.

3. Test files are always loaded, so one test file that does not build for the target blocks the whole package. tinygo fix -target pico -diff ./src/os/... fails type checking in os_test.go and stat_test.go (chtmpdir, os.SameFile). Maybe add a way to leave tests out, or skip test packages that fail to type check with a warning?

4. go1.25 is hardcoded in loader/analysis.go and must match minorMin in builder/config.go. Sharing one constant would keep them from drifting when the minimum Go version goes up.

What do you think? Thanks!

@davecheney thanks for working on fixing fix. I checked out this PR and ran the tests locally. Here are some notes edited from an automated review:

1. /... patterns under TinyGo's src find no packages. ./src/machine/..., ./src/machine/usb/..., ./src/internal/... and ./src/runtime/... all end with no packages matched. The cached GOROOT has those directories as symlinks, and go list does not follow symlinks for .... ./src/... turns into std, which fails with package net (test) imports internal/poll: build constraints exclude all Go files. The error for plain ./src also suggests ./src/.... Perhaps expand these patterns by walking $TINYGOROOT/src instead of passing them to go list, or at least change that hint?
2. The -diff output is always one hunk from the first change to the last, so unchanged lines in between show up as removed and added. For example tinygo fix -target pico -diff ./src/machine shows 83 lines of -/+ in machine_rp2_i2c.go and the whole roscRandByte function in machine_rp2_rng.go for two rangeint changes. The patch still applies, but it is hard to read. Separate hunks with 3 lines of context, like go fix -diff, might help.
3. Test files are always loaded, so one test file that does not build for the target blocks the whole package. tinygo fix -target pico -diff ./src/os/... fails type checking in os_test.go and stat_test.go (chtmpdir, os.SameFile). Maybe add a way to leave tests out, or skip test packages that fail to type check with a warning?
4. go1.25 is hardcoded in loader/analysis.go and must match minorMin in builder/config.go. Sharing one constant would keep them from drifting when the minimum Go version goes up.

What do you think? Thanks!

Thanks for the feedback. I'll take another pass at this in the morning. buenas noches