Ensure the right versions of packages are used when simulating pinning

Co-authored-by: Kate <kit-ty-kate@outlook.com>

master_changes.md

@@ -51,6 +51,7 @@ users)
   * [BUG] Stop double pin of packages located in ./opam/opam [#6343 @kit-ty-kate - fix #6342]
   * Don't ask confirmation when pinning an unknown package (absent from repositories) [#6309 @kit-ty-kate @rjbou - fix #3199]
   * [BUG] Do not ask to install pin-depends twice [#6375 @kit-ty-kate - fix #6374]
+  * [BUG] Ensure the right versions of packages are used when simulating pinning [#6256 @rjbou @kit-ty-kate - fix #6248 #6379]
 
 ## List
 

src/client/opamAuxCommands.ml

@@ -393,6 +393,15 @@ let simulate_local_pinnings ?quiet ?(for_view=false) st to_pin =
   } in
   st, local_packages
 
+let simulate_pinned_atoms pins atoms =
+  List.map (function
+      | (_name, Some _) as a -> a
+      | (name, None) as a ->
+        match OpamPackage.package_of_name_opt pins name with
+        | Some pkg -> (name, Some (`Eq, OpamPackage.version pkg))
+        | None -> a)
+    atoms
+
 let simulate_autopin st ?quiet ?(for_view=false) ?locked ?recurse ?subpath
     atom_or_local_list =
   let atoms, to_pin, obsolete_pins, already_pinned_set =
@@ -424,7 +433,7 @@ let simulate_autopin st ?quiet ?(for_view=false) ?locked ?recurse ?subpath
         OpamConsole.note "The following may not reflect the above pinnings (their \
                           package definitions are not available at this stage)";
         OpamConsole.msg "\n"));
-  st, atoms
+  st, simulate_pinned_atoms pins atoms
 
 let autopin st ?(simulate=false) ?quiet ?locked ?recurse ?subpath
     atom_or_local_list =
@@ -494,7 +503,7 @@ let autopin st ?(simulate=false) ?quiet ?locked ?recurse ?subpath
     else
       OpamUpdate.dev_packages st ~working_dir:OpamPackage.Set.empty already_pinned
   in
-  st, atoms
+  st, simulate_pinned_atoms pins atoms
 
 let check_and_revert_sandboxing root config =
   let sdbx_wrappers =

tests/reftests/pin.test

@@ -1060,10 +1060,11 @@ opam-version: "2.0"
 ### <pkg:deps-sim.2>
 opam-version: "2.0"
 ### opam install ./sim --deps-only
-The following actions will be performed:
-=== install 1 package
-  - install deps-sim 1 [required by sim]
-
-<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
--> installed deps-sim.1
-Done.
+[ERROR] Package conflict!
+  * Incompatible packages:
+    - (invariant) -> simcomp
+    - deps-of-sim
+    You can temporarily relax the switch invariant with `--update-invariant'
+
+No solution found, exiting
+# Return code 20 #