Merge pull request #10599 from stedolan/lazysigs

Evaluate signature substitutions lazily

Author: stedolan

.depend

@@ -1195,6 +1195,7 @@ typing/subst.cmo : \
     utils/misc.cmi \
     parsing/location.cmi \
     utils/local_store.cmi \
+    utils/lazy_backtrack.cmi \
     typing/ident.cmi \
     utils/clflags.cmi \
     typing/btype.cmi \
@@ -1207,6 +1208,7 @@ typing/subst.cmx : \
     utils/misc.cmx \
     parsing/location.cmx \
     utils/local_store.cmx \
+    utils/lazy_backtrack.cmx \
     typing/ident.cmx \
     utils/clflags.cmx \
     typing/btype.cmx \
@@ -1215,6 +1217,7 @@ typing/subst.cmx : \
 typing/subst.cmi : \
     typing/types.cmi \
     typing/path.cmi \
+    parsing/parsetree.cmi \
     parsing/location.cmi \
     typing/ident.cmi
 typing/tast_iterator.cmo : \

Changes

@@ -130,6 +130,9 @@ Working version
 - #10555: Do not use ghost locations for type constraints
   (Nicolás Ojeda Bär, report by Anton Bachin, review by Thomas Refis)
 
+- #10559: Evaluate signature substitutions lazily
+  (Stephen Dolan, review by Leo White)
+
 ### Build system:
 
 ### Bug fixes:

boot/ocamlc

@@ -304,7 +304,7 @@ module NN :
     val unit : unit
     external e : unit -> unit = "%identity"
     module M = N.M
-    module type T = sig end
+    module type T = N.T
     exception E
     type ext = N.ext = ..
     type ext += C
@@ -329,7 +329,7 @@ module Type :
     val unit : unit
     external e : unit -> unit = "%identity"
     module M = N.M
-    module type T = sig end
+    module type T = N.T
     exception E
     type ext = N.ext = ..
     type ext += C
@@ -352,7 +352,7 @@ module Module :
     val unit : unit
     external e : unit -> unit = "%identity"
     module M = N.M
-    module type T = sig end
+    module type T = N.T
     exception E
     type ext = N.ext = ..
     type ext += C
@@ -370,12 +370,12 @@ end
 [%%expect{|
 module Module_type :
   sig
-    module type U = sig end
+    module type U = N.T
     type t = N.t
     val unit : unit
     external e : unit -> unit = "%identity"
     module M = N.M
-    module type T = sig end
+    module type T = N.T
     exception E
     type ext = N.ext = ..
     type ext += C
@@ -398,7 +398,7 @@ module Exception :
     val unit : unit
     external e : unit -> unit = "%identity"
     module M = N.M
-    module type T = sig end
+    module type T = N.T
     exception E
     type ext = N.ext = ..
     type ext += C
@@ -421,7 +421,7 @@ module Extension :
     val unit : unit
     external e : unit -> unit = "%identity"
     module M = N.M
-    module type T = sig end
+    module type T = N.T
     exception E
     type ext = N.ext = ..
     type ext += C
@@ -444,7 +444,7 @@ module Class :
     val unit : unit
     external e : unit -> unit = "%identity"
     module M = N.M
-    module type T = sig end
+    module type T = N.T
     exception E
     type ext = N.ext = ..
     type ext += C
@@ -467,7 +467,7 @@ module Class_type :
     val unit : unit
     external e : unit -> unit = "%identity"
     module M = N.M
-    module type T = sig end
+    module type T = N.T
     exception E
     type ext = N.ext = ..
     type ext += C

boot/ocamllex

@@ -1310,22 +1310,14 @@ module Add_one' :
     module type t = arg -> sig type arg = A.arg end
   end
 module Add_one :
-  sig
-    type witness
-    module M = Add_one'.M
-    module type t = arg -> sig type arg = A.arg end
-  end
+  sig type witness module M = Add_one'.M module type t = Add_one'.t end
 module Add_three' :
   sig
     module M : arg -> arg -> arg -> sig type arg = A.arg end
     module type t = arg -> arg -> arg -> sig type arg = A.arg end
   end
 module Add_three :
-  sig
-    module M = Add_three'.M
-    module type t = arg -> arg -> arg -> sig type arg = A.arg end
-    type witness
-  end
+  sig module M = Add_three'.M module type t = Add_three'.t type witness end
 Line 22, characters 21-43:
 22 | module Wrong_intro = F(Add_three')(A)(A)(A)
                           ^^^^^^^^^^^^^^^^^^^^^^
@@ -1336,10 +1328,7 @@ Error: The functor application is ill-typed.
          functor (X : $T1) arg arg arg -> ...
        1. Modules do not match:
             Add_three' :
-            sig
-              module M = Add_three'.M
-              module type t = arg -> arg -> arg -> sig type arg = A.arg end
-            end
+            sig module M = Add_three'.M module type t = Add_three'.t end
           is not included in
             $T1 = sig type witness module type t module M : t end
           The type `witness' is required but not provided
@@ -1360,10 +1349,7 @@ Error: The functor application is ill-typed.
          functor (X : ...) arg arg arg -> ...
        1. The following extra argument is provided
               Add_one' :
-              sig
-                module M = Add_one'.M
-                module type t = arg -> sig type arg = A.arg end
-              end
+              sig module M = Add_one'.M module type t = Add_one'.t end
        2. Module Add_three matches the expected module type
        3. Module A matches the expected module type arg
        4. Module A matches the expected module type arg
@@ -1388,7 +1374,7 @@ Error: The functor application is ill-typed.
               sig
                 type witness = Add_one.witness
                 module M = Add_one'.M
-                module type t = arg -> sig type arg = A.arg end
+                module type t = Add_one.t
               end
        2. Module Add_three matches the expected module type
        3. Module A matches the expected module type arg