Fix #3624

Dune should insert the name of the extension to the dune-project file.

Signed-off-by: Rudi Grinberg <me@rgrinberg.com>

Author: rgrinberg

CHANGES.md

@@ -46,6 +46,9 @@ next
 - Use `{dev}` rather than `{pinned}` in the generated `.opam` file. (#3647,
   @kit-ty-kate)
 
+- Insert correct extension name when editing `dune-project` files. Previously,
+  dune would just insert the stanza name. (#3649, fixes #3624, @rgrinberg)
+
 2.6.1 (02/07/2020)
 ------------------
 

src/dune/dune_project.ml

@@ -433,7 +433,8 @@ module Extension = struct
                             ( Project_file_edit.append project_file
                                 (List
                                    [ Dune_lang.atom "using"
-                                   ; Dune_lang.atom name
+                                   ; Dune_lang.atom
+                                       (Dune_lang.Syntax.name e.syntax)
                                    ; Dune_lang.atom
                                        (Dune_lang.Syntax.Version.to_string
                                           version)

test/blackbox-tests/test-cases/coq/github3624.t/run.t

@@ -5,4 +5,4 @@ In github #3624, dune created a dune-project with an incorrect using line.
   >  (name foo))
   > EOF
   $ dune build 2>&1 | grep using
-  Info: Appending this line to dune-project: (using coq.theory 0.2)
+  Info: Appending this line to dune-project: (using coq 0.2)