ocaml · kit-ty-kate · Dec 22, 2025 · Dec 22, 2025
diff --git a/master_changes.md b/master_changes.md
@@ -24,6 +24,7 @@ users)
 ## Config report
 
 ## Actions
+  * The internal `sources` directory now only serves to cache dev packages instead of every packages, saving disk space [#6440 @kit-ty-kate - fix #4056 #5448]
 
 ## Install
 
@@ -35,6 +36,7 @@ users)
   * Read full lines when asking for user input when `TERM=dumb` [#6829 @arvidj - fix #6828]
 
 ## Switch
+  * The internal `sources` directory is now always created on switch creation [#6440 @kit-ty-kate]
 
 ## Config
 

diff --git a/src/client/opamSolution.ml b/src/client/opamSolution.ml
@@ -644,21 +644,22 @@ let parallel_apply t
               "" (OpamPackage.Map.find_opt nv inplace));
          Done (`Successful (installed, removed)))
       else
+      let source_dir = source_dir nv in
       let is_inplace, build_dir =
         try true, OpamPackage.Map.find nv inplace
         with Not_found ->
           let dir = OpamPath.Switch.build t.switch_global.root t.switch nv in
-          if not OpamClientConfig.(!r.reuse_build_dir) then
+          let source_dir_is_build_dir = OpamFilename.Dir.equal dir source_dir in
+          if not (OpamClientConfig.(!r.reuse_build_dir) || source_dir_is_build_dir) then
             OpamFilename.rmdir dir;
-          false, dir
+          source_dir_is_build_dir, dir
       in
       let test, doc, dev_setup =
         let found = OpamPackage.Set.mem nv requested in
         OpamStateConfig.(!r.build_test) && found,
         OpamStateConfig.(!r.build_doc) && found,
         OpamStateConfig.(!r.dev_setup) && found
       in
-      let source_dir = source_dir nv in
       (if OpamFilename.exists_dir source_dir
        then (if not is_inplace then
                OpamFilename.copy_dir ~src:source_dir ~dst:build_dir)

diff --git a/src/state/opamSwitchAction.ml b/src/state/opamSwitchAction.ml
@@ -66,6 +66,7 @@ let create_empty_switch gt ?synopsis ?repos ?invariant switch =
     OpamFilename.mkdir (OpamPath.Switch.lib_dir root switch config);
     OpamFilename.mkdir (OpamPath.Switch.stublibs root switch config);
     OpamFilename.mkdir (OpamPath.Switch.toplevel root switch config);
+    OpamFilename.mkdir (OpamPath.Switch.sources_dir root switch);
     OpamFilename.mkdir (OpamPath.Switch.build_dir root switch);
     OpamFilename.mkdir (OpamPath.Switch.bin root switch config);
     OpamFilename.mkdir (OpamPath.Switch.sbin root switch config);

diff --git a/src/state/opamSwitchState.ml b/src/state/opamSwitchState.ml
@@ -765,9 +765,12 @@ let is_version_pinned st name =
     | None -> false
 
 let source_dir st nv =
-  if OpamPackage.Set.mem nv st.pinned
-  then OpamPath.Switch.pinned_package st.switch_global.root st.switch nv.name
-  else OpamPath.Switch.sources st.switch_global.root st.switch nv
+  if OpamPackage.Set.mem nv st.pinned then
+    OpamPath.Switch.pinned_package st.switch_global.root st.switch nv.name
+  else if is_dev_package st nv then
+    OpamPath.Switch.sources st.switch_global.root st.switch nv
+  else
+    OpamPath.Switch.build st.switch_global.root st.switch nv
 
 let overlay_opam_file st name =
   if is_pinned st name then

diff --git a/tests/reftests/action-disk.test b/tests/reftests/action-disk.test
diff --git a/tests/reftests/dot-install.test b/tests/reftests/dot-install.test
@@ -128,7 +128,7 @@ ACTION                          prepare_package_source: dot.~dev at ${BASEDIR}/O
 ACTION                          Removing dot.~dev
 -> removed   dot.~dev
 Installing dot.~dev.
-TRACK                           after install: 0 elements, 0 added, scanned in 0.000s
+TRACK                           after install: 3 elements, 0 added, scanned in 0.000s
 -> installed dot.~dev
 ACTION                          Cleaning up artefacts of dot.~dev
 Done.
@@ -263,7 +263,6 @@ The following actions will be performed:
   - install no-specified-dir 1
 
 <><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-SYSTEM                          rmdir ${BASEDIR}/OPAM/rem-dir/.opam-switch/build/no-specified-dir.1
 SYSTEM                          mkdir ${BASEDIR}/OPAM/rem-dir/.opam-switch/build/no-specified-dir.1
 SYSTEM                          read ${BASEDIR}/OPAM/repo/default/packages/no-specified-dir/no-specified-dir.1/files/no-specified-dir.install
 SYSTEM                          write ${BASEDIR}/OPAM/rem-dir/.opam-switch/build/no-specified-dir.1/no-specified-dir.install
@@ -345,7 +344,9 @@ SYSTEM                          rmdir ${BASEDIR}/OPAM/rem-dir/.opam-switch/packa
 SYSTEM                          rm ${BASEDIR}/OPAM/rem-dir/.opam-switch/packages/no-specified-dir.1/opam
 SYSTEM                          rm ${BASEDIR}/OPAM/rem-dir/.opam-switch/packages/no-specified-dir.1/files/no-specified-dir.install
 SYSTEM                          rm ${BASEDIR}/OPAM/rem-dir/.opam-switch/packages/no-specified-dir.1/files/a-file
-SYSTEM                          rmdir ${BASEDIR}/OPAM/rem-dir/.opam-switch/sources/no-specified-dir.1
+SYSTEM                          rmdir ${BASEDIR}/OPAM/rem-dir/.opam-switch/build/no-specified-dir.1
+SYSTEM                          rm ${BASEDIR}/OPAM/rem-dir/.opam-switch/build/no-specified-dir.1/no-specified-dir.install
+SYSTEM                          rm ${BASEDIR}/OPAM/rem-dir/.opam-switch/build/no-specified-dir.1/a-file
 Done.
 SYSTEM                          LOCK ${BASEDIR}/OPAM/rem-dir/.opam-switch/lock (write => none)
 SYSTEM                          LOCK ${BASEDIR}/OPAM/rem-dir/.opam-switch/lock (none => none)

diff --git a/tests/reftests/download.test b/tests/reftests/download.test
@@ -188,7 +188,7 @@ The following actions will be performed:
   - install foo 1
 
 <><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-SYSTEM                          rmdir ${BASEDIR}/OPAM/download/.opam-switch/sources/foo.1
+SYSTEM                          rmdir ${BASEDIR}/OPAM/download/.opam-switch/build/foo.1
 SYSTEM                          mkdir ${OPAMTMP}
 Processing  1/1: [foo.1: rsync]
 + rsync "-rLptgoDvc" "--exclude" ".git" "--exclude" "_darcs" "--exclude" ".hg" "--exclude" ".#*" "--exclude" "_opam*" "--exclude" "_build" "--delete" "--delete-excluded" "${BASEDIR}/arch.tgz" "${OPAMTMP}"
@@ -197,8 +197,8 @@ SYSTEM                          copy ${OPAMTMP}/arch.tgz -> ${BASEDIR}/OPAM/down
 SYSTEM                          mkdir ${OPAMTMP}
 Processing  1/1: [foo.1: extract]
 + tar "xfz" "${OPAMTMP}/arch.tgz" "-C" "${OPAMTMP}"
-SYSTEM                          copydir ${OPAMTMP}/REPO -> ${BASEDIR}/OPAM/download/.opam-switch/sources/foo.1
-SYSTEM                          mkdir ${BASEDIR}/OPAM/download/.opam-switch/sources/foo.1
+SYSTEM                          copydir ${OPAMTMP}/REPO -> ${BASEDIR}/OPAM/download/.opam-switch/build/foo.1
+SYSTEM                          mkdir ${BASEDIR}/OPAM/download/.opam-switch/build/foo.1
 SYSTEM                          rmdir ${OPAMTMP}
 SYSTEM                          rmdir ${OPAMTMP}
 Done.
@@ -265,7 +265,7 @@ The following actions will be performed:
   - install baz 1
 
 <><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-SYSTEM                          rmdir ${BASEDIR}/OPAM/download/.opam-switch/sources/baz.1
+SYSTEM                          rmdir ${BASEDIR}/OPAM/download/.opam-switch/build/baz.1
 SYSTEM                          mkdir ${OPAMTMP}
 Processing  1/1: [baz.1: http]
 + wget "--header=Accept: */*" "-t" "3" "-O" "${OPAMTMP}/v1.0.0.tar.gz.part" "-U" "opam/current" "--" "https://github.com/UnixJunkie/get_line/archive/v1.0.0.tar.gz"
@@ -275,8 +275,8 @@ SYSTEM                          copy ${OPAMTMP}/v1.0.0.tar.gz -> ${BASEDIR}/OPAM
 SYSTEM                          mkdir ${OPAMTMP}
 Processing  1/1: [baz.1: extract]
 + tar "xfz" "${OPAMTMP}/v1.0.0.tar.gz" "-C" "${OPAMTMP}"
-SYSTEM                          copydir ${OPAMTMP}/get_line-1.0.0 -> ${BASEDIR}/OPAM/download/.opam-switch/sources/baz.1
-SYSTEM                          mkdir ${BASEDIR}/OPAM/download/.opam-switch/sources/baz.1
+SYSTEM                          copydir ${OPAMTMP}/get_line-1.0.0 -> ${BASEDIR}/OPAM/download/.opam-switch/build/baz.1
+SYSTEM                          mkdir ${BASEDIR}/OPAM/download/.opam-switch/build/baz.1
 SYSTEM                          rmdir ${OPAMTMP}
 SYSTEM                          rmdir ${OPAMTMP}
 Done.

diff --git a/tests/reftests/sources-directory-cleaning.test b/tests/reftests/sources-directory-cleaning.test
@@ -49,7 +49,6 @@ The following actions will be performed:
 -> installed waste.1
 Done.
 ### ls OPAM/sources-dir/.opam-switch/sources/
-waste.1
 ### : at removal
 ### opam remove waste
 The following actions will be performed:
@@ -71,7 +70,6 @@ The following actions will be performed:
 -> installed waste.1
 Done.
 ### ls OPAM/sources-dir/.opam-switch/sources
-waste.1
 ### opam reinstall waste
 The following actions will be performed:
 === recompile 1 package
@@ -83,7 +81,6 @@ The following actions will be performed:
 -> installed waste.1
 Done.
 ### ls OPAM/sources-dir/.opam-switch/sources
-waste.1
 ### : at atomic reinstall
 ### opam remove waste
 The following actions will be performed:
@@ -119,7 +116,6 @@ The following actions will be performed:
 -> installed waste.1
 Done.
 ### ls OPAM/sources-dir/.opam-switch/sources
-waste.1
 ### opam remove waste
 The following actions will be performed:
 === remove 1 package
@@ -156,7 +152,6 @@ The following actions will be performed:
 -> installed waste.1
 Done.
 ### ls OPAM/sources-dir/.opam-switch/sources
-waste.1
 ### opam remove waste
 The following actions will be performed:
 === remove 1 package