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rleshchinskiyRoman Leshchinskiy
rleshchinskiy
and
Roman Leshchinskiy
authored
flambda-backend: Abbreviate module types when printing error messages (#1895)
* Abbreviate module types when printing error messages Module types can become huge and pretty-printing them in error messages seems to be very slow. In one case, we produced a ~400k lines error message which took about 4 minutes to generate. This PR caps the overall number of signature elements we print and the depth to which we unfold module types. In my somewhat limited testing, this seemed to be the best heuristic I tried, although it is far from perfect. We can adjust later based on user feedback. * Add comments --------- Co-authored-by: Roman Leshchinskiy <[email protected]>
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‎testsuite/tests/typing-modules/abbreviate_in_error_messages.ml

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,98 @@
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(* TEST
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* expect
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*)
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module Width = struct
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module type S1 = sig
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val a : int
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val b : int
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val c : int
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val d : int
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val e : int
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end
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module type F = functor
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(X :
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sig
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module M1 : sig include S1 end
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module M2 : sig include S1 end
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module M3 : sig include S1 end
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module M4 : sig include S1 end
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module M5 : sig include S1 end
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module M6 : sig include S1 end
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module M7 : sig include S1 end
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end
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) -> S1
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module G(F:F)(X:functor() -> S1) = F(X)
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end
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[%%expect{|
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Line 24, characters 37-41:
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24 | module G(F:F)(X:functor() -> S1) = F(X)
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^^^^
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Error: Modules do not match: functor () -> S1 is not included in
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sig
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module M1 :
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sig
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val a : int
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val b : int
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val c : int
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val d : int
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val e : int
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end
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module M2 :
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sig val a : int val b : int val c : int val d : int ... end
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module M3 : sig ... end
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module M4 : sig ... end
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module M5 : sig ... end
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module M6 : sig ... end
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module M7 : sig ... end
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end
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Modules do not match:
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functor () -> ...
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is not included in
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functor -> ...
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An extra argument is provided of module type ()
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|}]
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module Depth = struct
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module type S = sig
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module M : sig
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module N : sig
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module O : sig
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module P : sig
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module Q : sig
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val x : int
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val y : int
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end
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end
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end
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end
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end
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end
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module type F = functor(X:S) -> S
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module F(F : F)(X : sig module M : sig end end) = F(X)
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end
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[%%expect{|
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Line 19, characters 52-56:
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19 | module F(F : F)(X : sig module M : sig end end) = F(X)
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^^^^
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Error: Modules do not match: sig module M : sig end end is not included in
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S
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In module M:
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Modules do not match:
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sig end
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is not included in
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sig
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module N :
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sig
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module O : sig module P : sig module Q : sig ... end end end
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end
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end
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In module M: The module `N' is required but not provided
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|}]

‎testsuite/tests/typing-modules/functors.ml

Lines changed: 4 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -921,37 +921,14 @@ Error: Signature mismatch:
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sig
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module B :
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sig
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module C :
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sig
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module D :
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sig
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module E :
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sig
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module F :
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functor (X : sig type x end)
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(Y : sig type y' end) (W : sig type w end) ->
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sig end
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end
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end
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end
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module C : sig module D : sig module E : sig ... end end end
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end
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end
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is not included in
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sig
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module B :
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sig
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module C :
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sig
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module D :
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sig
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module E :
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sig
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module F :
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sig type x end -> sig type y end ->
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sig type z end -> sig type w end -> sig end
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end
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end
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end
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module C : sig module D : sig module E : sig ... end end end
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end
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end
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In module B:
@@ -966,8 +943,8 @@ Error: Signature mismatch:
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module E :
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sig
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module F :
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sig type x end -> sig type y end ->
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sig type z end -> sig type w end -> sig end
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sig ... end -> sig ... end -> sig ... end ->
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sig ... end -> sig end
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end
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end
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end

‎testsuite/tests/typing-modules/illegal_permutation.ml

Lines changed: 4 additions & 64 deletions
Original file line numberDiff line numberDiff line change
@@ -502,22 +502,7 @@ Error: Signature mismatch:
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sig
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module C :
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functor (X : sig end) (Y : sig end)
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(Z : sig
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module D :
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sig
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module E :
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sig
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module F :
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functor (X : sig end)
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(Arg : sig
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val two : int
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val one : int
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end)
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-> sig end
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end
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end
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end)
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-> sig end
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(Z : sig ... end) -> sig end
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end
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end
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end
@@ -532,22 +517,7 @@ Error: Signature mismatch:
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sig
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module C :
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functor (X : sig end) (Y : sig end)
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(Z : sig
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module D :
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sig
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module E :
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sig
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module F :
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functor (X : sig end)
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(Arg : sig
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val one : int
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val two : int
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end)
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-> sig end
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end
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end
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end)
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-> sig end
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(Z : sig ... end) -> sig end
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end
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end
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end
@@ -561,22 +531,7 @@ Error: Signature mismatch:
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sig
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module C :
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functor (X : sig end) (Y : sig end)
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(Z : sig
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module D :
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sig
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module E :
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sig
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module F :
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functor (X : sig end)
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(Arg : sig
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val two : int
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val one : int
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end)
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-> sig end
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end
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end
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end)
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-> sig end
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(Z : sig module D : sig ... end end) -> sig end
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end
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end
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end
@@ -589,22 +544,7 @@ Error: Signature mismatch:
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sig
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module C :
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functor (X : sig end) (Y : sig end)
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(Z : sig
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module D :
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sig
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module E :
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sig
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module F :
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functor (X : sig end)
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(Arg : sig
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val one : int
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val two : int
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end)
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-> sig end
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end
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end
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end)
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-> sig end
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(Z : sig module D : sig ... end end) -> sig end
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end
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end
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end

‎typing/includemod_errorprinter.ml

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -203,7 +203,7 @@ let show_locs ppf (loc1, loc2) =
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let dmodtype mty =
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let tmty = Printtyp.tree_of_modtype mty in
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let tmty = Printtyp.tree_of_modtype ~abbrev:true mty in
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Format.dprintf "%a" !Oprint.out_module_type tmty
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let space ppf () = Format.fprintf ppf "@ "
@@ -666,22 +666,22 @@ let module_types {Err.got=mty1; expected=mty2} =
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Format.dprintf
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"@[<hv 2>Modules do not match:@ \
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%a@;<1 -2>is not included in@ %a@]"
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!Oprint.out_module_type (Printtyp.tree_of_modtype mty1)
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!Oprint.out_module_type (Printtyp.tree_of_modtype mty2)
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!Oprint.out_module_type (Printtyp.tree_of_modtype ~abbrev:true mty1)
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!Oprint.out_module_type (Printtyp.tree_of_modtype ~abbrev:true mty2)
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let eq_module_types {Err.got=mty1; expected=mty2} =
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Format.dprintf
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"@[<hv 2>Module types do not match:@ \
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%a@;<1 -2>is not equal to@ %a@]"
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!Oprint.out_module_type (Printtyp.tree_of_modtype mty1)
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!Oprint.out_module_type (Printtyp.tree_of_modtype mty2)
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!Oprint.out_module_type (Printtyp.tree_of_modtype ~abbrev:true mty1)
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!Oprint.out_module_type (Printtyp.tree_of_modtype ~abbrev:true mty2)
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let module_type_declarations id {Err.got=d1 ; expected=d2} =
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Format.dprintf
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"@[<hv 2>Module type declarations do not match:@ \
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%a@;<1 -2>does not match@ %a@]"
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!Oprint.out_sig_item (Printtyp.tree_of_modtype_declaration id d1)
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!Oprint.out_sig_item (Printtyp.tree_of_modtype_declaration id d2)
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!Oprint.out_sig_item (Printtyp.tree_of_modtype_declaration ~abbrev:true id d1)
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!Oprint.out_sig_item (Printtyp.tree_of_modtype_declaration ~abbrev:true id d2)
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let interface_mismatch ppf (diff: _ Err.diff) =
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Format.fprintf ppf

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