ocaml/merlin

truncated error message with Emacs+Merlin on OCaml 5.04 and v5.7.1-504

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#2080 aperta il 18 giu 2026

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Descrizione

Repro case:

module type A = sig type a end
module type B = sig type b end

module A : A = struct type a end
module B : B = struct type b end

module F (_ : A) (_ : B) = struct end

module Test = F(B)(A)

Merlin shows the following error message:

2. Modules do not match: A : sig type a = A.a end is not included in B

(The exact same thing is in the *Messages* and *merlin-errors* buffer.)

This is only the last line of the full error message shown by the compiler:

Error: This application of the functor F is ill-typed.
       These arguments:
         B A
       do not match these parameters:
         (Arg : A) (Arg : B) -> ...
       1. Modules do not match:
            B : sig type b = B.b end
          is not included in
            A
          The type a is required but not provided
          File "test.ml", line 1, characters 20-26: Expected declaration
       2. Modules do not match: A : sig type a = A.a end is not included in B

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