Fix #3026

Signed-off-by: Jeremie Dimino <[email protected]>

CHANGES.md

@@ -17,6 +17,10 @@
 - It is now an error to have a preprocessing dependency on a ppx rewriter
   library that is not marked as `(kind ppx_rewriter)` (#3039, @snowleopard).
 
+- Fix permissions of files promoted to the source tree when using the
+  shared cache. In particular, make them writable by the user (#3043,
+  fixes #3026, @diml)
+
 2.1.3 (16/01/2020)
 ------------------
 

src/dune/build_system.ml

@@ -1685,8 +1685,13 @@ end = struct
                 if lifetime = Until_clean then
                   Promoted_to_delete.add in_source_tree;
                 Scheduler.ignore_for_watch in_source_tree;
+                (* The file in the build directory might be read-only if it
+                   comes from the shared cache. However, we want the file in the
+                   source tree to be writable by the user, so we explicitly set
+                   the user writable bit. *)
+                let chmod n = n lor 0o200 in
                 Artifact_substitution.copy_file () ~src:path ~dst:in_source_tree
-                  ~get_vcs:File_tree.nearest_vcs ))
+                  ~get_vcs:File_tree.nearest_vcs ~chmod ))
     in
     t.rule_done <- t.rule_done + 1
 

test/blackbox-tests/test-cases/dune-cache/promotion-in-source-tree/run.t

@@ -44,5 +44,3 @@ into the file after the second run.
   Hello, world!
 
   $ echo plop > file
-  sh: file: Permission denied
-  [1]