The reverse feature relied on `GoFiles` from `go list`,
but that list may not be enough to typecheck a package:
typecheck error: $WORK/main.go:3:15: undeclared name: longMain
`go help list` shows:
GoFiles []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
CgoFiles []string // .go source files that import "C"
CompiledGoFiles []string // .go files presented to compiler (when using -compiled)
In other words, to mimic the same list of Go files fed to the compiler,
we want CompiledGoFiles.
Note that, since the cgo files show up as generated files,
we currently do not support reversing their filenames.
That is left as a TODO for now.
Updates #555.
Following the best practices from upstream.
In particular, the "txt" extension is somewhat ambiguous.
This may cause some conflicts due to the git diff noise,
but hopefully we won't ever do this again.