Fix $SHLVL

Due to being read-only, SHLVL wasn't being incremented properly for
recursive invocations of fish.

3 files changed, 8 insertions, 1 deletions

diff --git a/env.cpp b/env.cpp
index 91bc7ac8..353085b8 100644
--- a/env.cpp
+++ b/env.cpp
@@ -443,7 +443,7 @@ void env_init(const struct config_paths_t *paths /* or NULL */)
         L"LINES",
         L"COLUMNS",
         L"PWD",
-        L"SHLVL",
+        //L"SHLVL", // will be inserted a bit lower down
         L"FISH_VERSION",
     };
     for (size_t i=0; i < sizeof ro_keys / sizeof *ro_keys; i++)
@@ -549,6 +549,7 @@ void env_init(const struct config_paths_t *paths /* or NULL */)
         }
     }
     env_set(L"SHLVL", nshlvl_str.c_str(), ENV_GLOBAL | ENV_EXPORT);
+    env_read_only.insert(L"SHLVL");
 
     /* Set up the HOME variable */
     if (env_get_string(L"HOME").missing_or_empty())
diff --git a/tests/test3.in b/tests/test3.in
index 1bbacc0e..56cceeb5 100644
--- a/tests/test3.in
+++ b/tests/test3.in
@@ -233,4 +233,8 @@ echo $testu
 echo Missing: $testu
 ../fish -c 'echo Missing: $testu'
 
+# test SHLVL
+# use a subshell to ensure a clean slate
+env SHLVL= ../fish -c 'echo SHLVL: $SHLVL; ../fish -c \'echo SHLVL: $SHLVL\''
+
 true
diff --git a/tests/test3.out b/tests/test3.out
index d6cbdb9c..50563c05 100644
--- a/tests/test3.out
+++ b/tests/test3.out
@@ -21,3 +21,5 @@ Testing Universal Startup
 2
 Missing:
 Missing:
+SHLVL: 1
+SHLVL: 2