fix: enabled_if with env variable (ocaml#10936)

* fix: enabled_if with `env` variable

Signed-off-by: Alpha DIALLO <moyodiallo@gmail.com>

doc/changes/10936.md

@@ -0,0 +1 @@
+- Fix `enabled_if` when it uses `env` variable. (#10936, fixes #10905, @moyodiallo)

src/dune_rules/enabled_if.ml

@@ -19,6 +19,7 @@ let common_vars_list =
   ; "ocaml_version"
   ; "context_name"
   ; "arch_sixtyfour"
+  ; "env"
   ]
 ;;
 
@@ -29,6 +30,7 @@ let common_vars ~since =
          match var with
          | "context_name" -> var, (2, 7)
          | "arch_sixtyfour" -> var, (3, 11)
+         | "env" -> var, (3, 15)
          | _ -> var, since)
        common_vars_list)
 ;;
@@ -53,24 +55,24 @@ let decode_value ~allowed_vars ?(is_error = true) () =
     Blang.Ast.decode
       ~override_decode_bare_literal:None
       (String_with_vars.decode_manually (fun env var ->
-         match Dune_lang.Template.Pform.payload var with
-         | Some _ ->
+         let name = Dune_lang.Template.Pform.name var in
+         if List.exists ~f:(String.equal name) common_vars_list
+         then (
+           match List.assoc allowed_vars name with
+           | None ->
+             emit_warning allowed_vars is_error var;
+             Pform.Env.parse env var
+           | Some min_ver ->
+             let current_ver = Pform.Env.syntax_version env in
+             if min_ver > current_ver
+             then (
+               let loc = Dune_lang.Template.Pform.loc var in
+               let what = Dune_lang.Template.Pform.describe var in
+               Dune_lang.Syntax.Error.since loc Stanza.syntax min_ver ~what)
+             else Pform.Env.unsafe_parse_without_checking_version env var)
+         else (
            emit_warning allowed_vars is_error var;
-           Pform.Env.parse env var
-         | None ->
-           let name = Dune_lang.Template.Pform.name var in
-           (match List.assoc allowed_vars name with
-            | None ->
-              emit_warning allowed_vars is_error var;
-              Pform.Env.parse env var
-            | Some min_ver ->
-              let current_ver = Pform.Env.syntax_version env in
-              if min_ver > current_ver
-              then (
-                let loc = Dune_lang.Template.Pform.loc var in
-                let what = Dune_lang.Template.Pform.describe var in
-                Dune_lang.Syntax.Error.since loc Stanza.syntax min_ver ~what)
-              else Pform.Env.unsafe_parse_without_checking_version env var)))
+           Pform.Env.parse env var)))
 ;;
 
 let decode ~allowed_vars ?is_error ~since () =

test/blackbox-tests/test-cases/enabled_if/eif-env-vars.t

@@ -0,0 +1,52 @@
+Test enabled_if with 'env' variable.
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.14)
+  > (name dune-test)
+  > (package
+  >  (name dune-test))
+  > EOF
+
+  $ cat > dune <<EOF
+  > (executable
+  >  (name main)
+  >  (public_name dune_test)
+  >  (modules main)
+  >  (package dune-test)
+  >  (modes exe))
+  > (executable
+  >  (name main_2)
+  >  (public_name dune_test_2)
+  >  (enabled_if (= enabled %{env:MYVAR=disabled}))
+  >  (modules main_2)
+  >  (package dune-test)
+  >  (modes exe))
+  > EOF
+
+  $ MYVAR=disabled dune exec -- dune_test
+  File "dune", line 10, characters 24-45:
+  10 |  (enabled_if (= enabled %{env:MYVAR=disabled}))
+                               ^^^^^^^^^^^^^^^^^^^^^
+  Error: %{env:..} is only available since version 3.15 of the dune language.
+  Please update your dune-project file to have (lang dune 3.15).
+  [1]
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.15)
+  > (name dune-test)
+  > (package
+  >  (name dune-test))
+  > EOF
+
+  $ cat > main.ml <<EOF
+  > let () = print_string "Hello world"
+  > EOF
+
+  $ MYVAR=disabled dune exec -- dune_test
+  Hello world
+  $ MYVAR=enabled dune exec -- dune_test
+  File "dune", line 11, characters 10-16:
+  11 |  (modules main_2)
+                 ^^^^^^
+  Error: Module Main_2 doesn't exist.
+  [1]

test/blackbox-tests/test-cases/enabled_if/eif-exec-forbidden_var.t/run.t

@@ -8,8 +8,8 @@ The next ones use forbidden variables For dune 2.3 -> 2.5 it is a warning
   3 |  (enabled_if (<> %{project_root} "")))
                        ^^^^^^^^^^^^^^^
   Warning: Only architecture, system, model, os_type, ccomp_type, profile,
-  ocaml_version, context_name and arch_sixtyfour variables are allowed in this
-  'enabled_if' field. Please upgrade your dune language to at least 3.15.
+  ocaml_version, context_name, arch_sixtyfour and env variables are allowed in
+  this 'enabled_if' field. Please upgrade your dune language to at least 3.15.
   bar
 
 For dune >= 2.6 it is an error
@@ -21,6 +21,6 @@ For dune >= 2.6 it is an error
   3 |  (enabled_if (<> %{project_root} "")))
                        ^^^^^^^^^^^^^^^
   Error: Only architecture, system, model, os_type, ccomp_type, profile,
-  ocaml_version, context_name and arch_sixtyfour variables are allowed in this
-  'enabled_if' field. Please upgrade your dune language to at least 3.15.
+  ocaml_version, context_name, arch_sixtyfour and env variables are allowed in
+  this 'enabled_if' field. Please upgrade your dune language to at least 3.15.
   [1]

test/blackbox-tests/test-cases/enabled_if/eif-install-forbidden_var.t/run.t

@@ -4,6 +4,6 @@ Tests for enabled_if in install stanza using forbidden variable.
   6 |  (enabled_if (= %{project_root} ""))
                       ^^^^^^^^^^^^^^^
   Error: Only architecture, system, model, os_type, ccomp_type, profile,
-  ocaml_version, context_name and arch_sixtyfour variables are allowed in this
-  'enabled_if' field. Please upgrade your dune language to at least 3.15.
+  ocaml_version, context_name, arch_sixtyfour and env variables are allowed in
+  this 'enabled_if' field. Please upgrade your dune language to at least 3.15.
   [1]