Fix REPL - #113
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The REPL starts by evaluating an in-memory chunk named `main`. That uri was
passed to the CLI's file resolver, which called realpath on it and failed, so
the REPL exited immediately with:
CompileError: Import path does not exist: `main`
An entry chunk has no importing chunk, so it can be in-memory and resolve to
itself. Only entry chunks are treated this way, leaving `use main` from a
script resolving to a file as before.
REPL.new() bound the new REPL to a local and returned it. Returning a local
copies it into the return slot and then runs the block's destructors on the
local, so `VM.@deinit` freed the VM that the returned copy still points at.
The next eval crashed in Compiler.clearReports on a dangling pointer.
This works around the problem rather than fixing it. Any record owning a type
with a destructor hands the caller freed memory when returned this way:
type Holder:
vm cy.VM
fn make() -> Holder:
h := Holder{ vm = cy.VM() }
return h
h := make()
r := h.vm.eval('print(1)') -- crash
Returning the literal directly is fine, so it is specifically binding to a
named local and returning it. There is no move tracking to skip destructing a
returned local, so REPL.new now returns the record literal, and the init eval
moved to a separate `init` that runs in the caller's scope.
The compiler is reused across evals, and persist_main re-declares the previous main's top level syms in the new main chunk. Two things carried over wrongly. The skip list named `@main_init` and `@main_deinit`, which no longer exist; the hidden funcs are `@program_init` and `@program_deinit`. So they were carried over and collided with the ones reserved for the new main, and reporting that duplicate panicked in Sym.declNode on a `.use_alias`. Every line after the first failed. `main` was also treated as the entry point of every line. Each REPL line is compiled as its own program, so declaring `fn main()` on a line ran it, and it then stayed the entry point for the rest of the session: later lines re-ran it and were rejected with "Body statement is not allowed when main function is declared". A carried over `main` arrives as a use alias, which the unchecked cast to `.func` panicked on. `main` is not special in a session that continues across evals; it is an ordinary function that can be called by name. `main_func` is also reset per compile, since it was previously only ever assigned.
Each case is a list of input lines and the exact output the REPL prints for them. The driver runs the same read/eval_print loop as `cy.repl`, minus the intro banner, which carries a build specific version string. Covers the regressions fixed in this branch: `main` is an ordinary function rather than an entry point, so declaring it runs nothing and it stays callable by name; and a line that fails to compile does not stop the following lines from evaluating. Cases feed whole statements per entry rather than driving `read`'s multi-line buffering, since `input_buffer` currently leaks the concatenated string.
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Running the repl from commit c853fcc did not invoke the cyber-written repl
code. In addition a few other fixes were needed to make the REPL work.
A few basic tests were added for the REPL.
Defining
fn main()in a REPL session no longer runs it. Previously it wastreated as an entry point.
Still broken
read()leaks the concatenatedinput_buffer.path (
value_desc) is currently unreachable.Built and tested with zig 0.15.2;
zig build testpasses.