`line_coverage` compiler option in `-compile` attribute

[pguyot]

Describe the bug I don't seem to be able to enable line_coverage compiler option using -compile attribute. This is not consistent with compile documentation that says:

All options, except the include path ({i,Dir}), can also be given in the file with attribute -compile([Option,...]). Attribute -compile() is allowed after the function definitions.

Am I doing something wrong?

To Reproduce With OTP 27 or 27.1.1 erlc compiler, compile the following:

-module(test_executable_line).
-compile([line_coverage]).
-export([start/0]).

start() ->
    ok = test_executable_line(),
    0.

test_executable_line() ->
    ModuleInfo = ?MODULE:module_info(),
    CompileList = proplists_get_value(compile, ModuleInfo),
    true = is_list(CompileList),
    OptionsList = proplists_get_value(options, CompileList),
    erlang:display({compile_options, OptionsList}),
    erlang:display({emu_flavor, erlang:system_info(emu_flavor)}),
    ok.

proplists_get_value(_Key, []) -> undefined;
proplists_get_value(Key, [{Key, Value} | _Tail]) -> Value;
proplists_get_value(Key, [_Pair | Tail]) -> proplists_get_value(Key, Tail).

Alternatively, replace line 2 with:

-compile(line_coverage).

line_coverage is never included in the options in the module info. Besides, compiling with -S shows that indeed executable_line opcode is not emitted.

Alternatively, compile with erlc +line_coverage and the option is in module info and executable_line opcode is emitted.

Expected behavior I expect to be able to generate executable_line opcodes using -compile attribute.

Affected versions This is 27.0 and 27.1.1.

Additional context I'm trying to implement and test executable_line opcode in AtomVM after watching @bjorng excellent and insightful talk at CodeBEAM Europe 2024 as I realized we are missing it.

[bjorng]

Thanks for the bug report and your kind words about my talk. It was nice meeting you at the conference. I am impressed how the AtomVM is able to execute BEAM in such a small amount of memory.

The linked pull request fixes the bug. It will be included in Erlang/OTP 27.2.