Replace GetSymbolTable and derivatives with GetOrInit method

[jakebailey]

A new method:

func (s *SymbolTable) GetOrInit() SymbolTable {
	if *s == nil {
		*s = make(SymbolTable)
	}
	return *s
}

Operates on the address of a symbol table; when calling it on a SymbolTable, usually on a struct field, Go will take the address of whatever SymbolTable it's accessing, allowing this method to mutate it.

This makes it clearer that this operation is a mutating one, unsafe for concurrent use; if you need to find all modifiers, you can just look for anyone assigning to SymbolTable or calling this method. (It also means you can find-references on them again.)

In terms of performance, it inlines; godbolt pegs it as two instructions (it probably was before).

In adding this, I've vetted everything that used to use the old methods; the binder is of course fine. The checker seemed suspect when I was fixing races previously, but it's not, as the modifications are only on merged symbols (which are either clones or transient symbols local to a checker), or were being called on SymbolTable fields on types, which are also local to a checker.

[Copilot]

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (3)

internal/binder/binder.go:356

• [nitpick] The name getMembers might be ambiguous. Consider renaming it to something more descriptive, such as getOrInitMembers.

func getMembers(symbol *ast.Symbol) ast.SymbolTable {

internal/binder/binder.go:360

• [nitpick] The name getExports might be ambiguous. Consider renaming it to something more descriptive, such as getOrInitExports.

func getExports(symbol *ast.Symbol) ast.SymbolTable {

internal/binder/binder.go:364

• [nitpick] The name getLocals might be ambiguous. Consider renaming it to something more descriptive, such as getOrInitLocals.

func getLocals(container *ast.Node) ast.SymbolTable {

[Copilot]

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.