In 1.18, escript generated when `consolidate_protocols: false` stopped working

[angelikatyborska]

Elixir and Erlang/OTP versions

Erlang/OTP 27 [erts-15.2] [source] [64-bit] [smp:10:10] [ds:10:10:10] [async-threads:1] [jit]

Elixir 1.18.0 (compiled with Erlang/OTP 27)

Operating system

macOS 14.5

Current behavior

We have a project that's an escript that accepts user-submitted Elixir code and spits out static code analysis hints, including warnings from the compiler. To avoid reporting warnings about protocols being already consolidated, we compile the escript with consolidate_protocols: false.

That escript stopped working in Elixir 1.18. The size of the generated binary is surprisingly smaller than before, and trying to run it spits out an error error: {error,{elixir,{"no such file or directory","elixir.app"}}}. Details below.

I created a reproduction repository with the simplest possible reproduction: https://github.com/angelikatyborska/elixir-1-18-escript-consolidate-protocols-false-bug

Step 1: generate working escript

When we don't set consolidate_protocols: false, we're able to generate a working escript.

Generate and execute the escript:

$ mix escript.build
Generated orange app
Generated escript orange with MIX_ENV=dev

$ ./orange 
Orange you glad you ran this binary? Have a nice day 🍊

Note the size of the generated working binary: 1.3M

$ ls orange 
-rwxr-xr-x  1 angelika  staff   1.3M Dec 21 10:42 orange

Step 2: set consolidate_protocols: false

In mix.exs, add consolidate_protocols: false:

diff --git a/mix.exs b/mix.exs
index ed076a0..5e181c9 100644
--- a/mix.exs
+++ b/mix.exs
@@ -8,6 +8,7 @@ defmodule Orange.MixProject do
       elixir: "~> 1.18",
       start_permanent: Mix.env() == :prod,
       deps: deps(),
+      consolidate_protocols: false,
       escript: [main_module: Orange]
     ]
   end

Then try generating the escript again:

$ mix escript.build
Generated orange app
Generated escript orange with MIX_ENV=dev

$ ./orange 
ERROR! Failed to start Elixir.
error: {error,{elixir,{"no such file or directory","elixir.app"}}}

The script doesn't run anymore. Note the size of the generated broken binary: 1.6K compared to 1.3M, significantly smaller than expected.

$ ls orange
-rwxr-xr-x  1 angelika  staff   1.6K Dec 21 10:45 orange

I have also tested this in Elixir 1.17.3 and there, a working binary compiled with consolidate_protocols: false has the size of 1.2M.

Expected behavior

I would expect to be able to build an escript with the option consolidate_protocols: false and for the escript to execute.

[josevalim]

Thank you, we will fix it and make sure it is part of the next patch.