Implement unsetting variables

src/analyzer.rs

@@ -37,6 +37,8 @@ impl<'src> Analyzer<'src> {
 
     let mut modules: Table<Justfile> = Table::new();
 
+    let mut unsets: HashSet<String> = HashSet::new();
+
     let mut definitions: HashMap<&str, (&'static str, Name)> = HashMap::new();
 
     let mut define = |name: Name<'src>,
@@ -98,6 +100,9 @@ impl<'src> Analyzer<'src> {
             self.analyze_set(set)?;
             self.sets.insert(set.clone());
           }
+          Item::Unset { name } => {
+            unsets.insert(name.lexeme().to_string());
+          }
         }
       }
 
@@ -166,6 +171,7 @@ impl<'src> Analyzer<'src> {
       name,
       recipes,
       settings,
+      unsets,
       warnings,
     })
   }

src/command_ext.rs

@@ -1,25 +1,41 @@
 use super::*;
 
 pub(crate) trait CommandExt {
-  fn export(&mut self, settings: &Settings, dotenv: &BTreeMap<String, String>, scope: &Scope);
+  fn export(
+    &mut self,
+    settings: &Settings,
+    dotenv: &BTreeMap<String, String>,
+    scope: &Scope,
+    unsets: &HashSet<String>,
+  );
 
-  fn export_scope(&mut self, settings: &Settings, scope: &Scope);
+  fn export_scope(&mut self, settings: &Settings, scope: &Scope, unsets: &HashSet<String>);
 }
 
 impl CommandExt for Command {
-  fn export(&mut self, settings: &Settings, dotenv: &BTreeMap<String, String>, scope: &Scope) {
+  fn export(
+    &mut self,
+    settings: &Settings,
+    dotenv: &BTreeMap<String, String>,
+    scope: &Scope,
+    unsets: &HashSet<String>,
+  ) {
     for (name, value) in dotenv {
       self.env(name, value);
     }
 
     if let Some(parent) = scope.parent() {
-      self.export_scope(settings, parent);
+      self.export_scope(settings, parent, unsets);
     }
   }
 
-  fn export_scope(&mut self, settings: &Settings, scope: &Scope) {
+  fn export_scope(&mut self, settings: &Settings, scope: &Scope, unsets: &HashSet<String>) {
     if let Some(parent) = scope.parent() {
-      self.export_scope(settings, parent);
+      self.export_scope(settings, parent, unsets);
+    }
+
+    for unset in unsets {
+      self.env_remove(unset);
     }
 
     for binding in scope.bindings() {

src/evaluator.rs

@@ -7,6 +7,7 @@ pub(crate) struct Evaluator<'src: 'run, 'run> {
   pub(crate) scope: Scope<'src, 'run>,
   pub(crate) settings: &'run Settings<'run>,
   pub(crate) search: &'run Search,
+  unsets: &'run HashSet<String>,
 }
 
 impl<'src, 'run> Evaluator<'src, 'run> {
@@ -17,6 +18,7 @@ impl<'src, 'run> Evaluator<'src, 'run> {
     overrides: Scope<'src, 'run>,
     settings: &'run Settings<'run>,
     search: &'run Search,
+    unsets: &'run HashSet<String>,
   ) -> RunResult<'src, Scope<'src, 'run>> {
     let mut evaluator = Self {
       scope: overrides,
@@ -25,6 +27,7 @@ impl<'src, 'run> Evaluator<'src, 'run> {
       dotenv,
       settings,
       search,
+      unsets,
     };
 
     for assignment in assignments.values() {
@@ -214,7 +217,7 @@ impl<'src, 'run> Evaluator<'src, 'run> {
     cmd.arg(command);
     cmd.args(args);
     cmd.current_dir(&self.search.working_directory);
-    cmd.export(self.settings, self.dotenv, &self.scope);
+    cmd.export(self.settings, self.dotenv, &self.scope, self.unsets);
     cmd.stdin(Stdio::inherit());
     cmd.stderr(if self.config.verbosity.quiet() {
       Stdio::null()
@@ -257,6 +260,7 @@ impl<'src, 'run> Evaluator<'src, 'run> {
     scope: &'run Scope<'src, 'run>,
     settings: &'run Settings,
     search: &'run Search,
+    unsets: &'run HashSet<String>,
   ) -> RunResult<'src, (Scope<'src, 'run>, Vec<String>)> {
     let mut evaluator = Self {
       assignments: None,
@@ -265,6 +269,7 @@ impl<'src, 'run> Evaluator<'src, 'run> {
       settings,
       dotenv,
       config,
+      unsets,
     };
 
     let mut scope = scope.child();
@@ -310,6 +315,7 @@ impl<'src, 'run> Evaluator<'src, 'run> {
     scope: &'run Scope<'src, 'run>,
     settings: &'run Settings,
     search: &'run Search,
+    unsets: &'run HashSet<String>,
   ) -> Evaluator<'src, 'run> {
     Self {
       assignments: None,
@@ -318,6 +324,7 @@ impl<'src, 'run> Evaluator<'src, 'run> {
       settings,
       dotenv,
       config,
+      unsets,
     }
   }
 }

src/item.rs

@@ -20,6 +20,9 @@ pub(crate) enum Item<'src> {
   },
   Recipe(UnresolvedRecipe<'src>),
   Set(Set<'src>),
+  Unset {
+    name: Name<'src>,
+  },
 }
 
 impl<'src> Display for Item<'src> {
@@ -61,6 +64,7 @@ impl<'src> Display for Item<'src> {
       }
       Self::Recipe(recipe) => write!(f, "{}", recipe.color_display(Color::never())),
       Self::Set(set) => write!(f, "{set}"),
+      Self::Unset { name } => write!(f, "unset {name}"),
     }
   }
 }

src/justfile.rs

@@ -21,6 +21,7 @@ pub(crate) struct Justfile<'src> {
   pub(crate) name: Option<Name<'src>>,
   pub(crate) recipes: Table<'src, Rc<Recipe<'src>>>,
   pub(crate) settings: Settings<'src>,
+  pub(crate) unsets: HashSet<String>,
   pub(crate) warnings: Vec<Warning>,
 }
 
@@ -109,6 +110,7 @@ impl<'src> Justfile<'src> {
       scope,
       &self.settings,
       search,
+      &self.unsets,
     )
   }
 
@@ -159,7 +161,7 @@ impl<'src> Justfile<'src> {
 
         let scope = scope.child();
 
-        command.export(&self.settings, &dotenv, &scope);
+        command.export(&self.settings, &dotenv, &scope, &self.unsets);
 
         let status = InterruptHandler::guard(|| command.status()).map_err(|io_error| {
           Error::CommandInvoke {
@@ -280,6 +282,7 @@ impl<'src> Justfile<'src> {
         config,
         scope: invocation.scope,
         search,
+        unsets: &self.unsets,
       };
 
       Self::run_recipe(
@@ -433,12 +436,19 @@ impl<'src> Justfile<'src> {
       context.scope,
       context.settings,
       search,
+      context.unsets,
     )?;
 
     let scope = outer.child();
 
-    let mut evaluator =
-      Evaluator::recipe_evaluator(context.config, dotenv, &scope, context.settings, search);
+    let mut evaluator = Evaluator::recipe_evaluator(
+      context.config,
+      dotenv,
+      &scope,
+      context.settings,
+      search,
+      context.unsets,
+    );
 
     if !context.config.no_dependencies {
       for Dependency { recipe, arguments } in recipe.dependencies.iter().take(recipe.priors) {

src/keyword.rs

@@ -24,6 +24,7 @@ pub(crate) enum Keyword {
   Shell,
   Tempdir,
   True,
+  Unset,
   WindowsPowershell,
   WindowsShell,
   X,

src/lib.rs

@@ -41,7 +41,7 @@ pub(crate) use {
   std::{
     borrow::Cow,
     cmp,
-    collections::{BTreeMap, BTreeSet, HashMap},
+    collections::{BTreeMap, BTreeSet, HashMap, HashSet},
     env,
     ffi::OsString,
     fmt::{self, Debug, Display, Formatter},

src/node.rs

@@ -54,6 +54,11 @@ impl<'src> Node<'src> for Item<'src> {
       }
       Self::Recipe(recipe) => recipe.tree(),
       Self::Set(set) => set.tree(),
+      Self::Unset { name } => {
+        let mut unset = Tree::atom(Keyword::Unset.lexeme());
+        unset.push_mut(name.lexeme().replace('-', "_"));
+        unset
+      }
     }
   }
 }

src/parser.rs

@@ -340,6 +340,11 @@ impl<'run, 'src> Parser<'run, 'src> {
             self.presume_keyword(Keyword::Export)?;
             items.push(Item::Assignment(self.parse_assignment(true)?));
           }
+          Some(Keyword::Unset) => {
+            self.presume_keyword(Keyword::Unset)?;
+            let name = self.parse_name()?;
+            items.push(Item::Unset { name });
+          }
           Some(Keyword::Import)
             if self.next_are(&[Identifier, StringToken])
               || self.next_are(&[Identifier, Identifier, StringToken])

src/recipe.rs

@@ -164,8 +164,14 @@ impl<'src, D> Recipe<'src, D> {
       );
     }
 
-    let evaluator =
-      Evaluator::recipe_evaluator(context.config, dotenv, &scope, context.settings, search);
+    let evaluator = Evaluator::recipe_evaluator(
+      context.config,
+      dotenv,
+      &scope,
+      context.settings,
+      search,
+      context.unsets,
+    );
 
     if self.shebang {
       self.run_shebang(context, dotenv, &scope, positional, config, evaluator)
@@ -264,7 +270,7 @@ impl<'src, D> Recipe<'src, D> {
         cmd.stdout(Stdio::null());
       }
 
-      cmd.export(context.settings, dotenv, scope);
+      cmd.export(context.settings, dotenv, scope, context.unsets);
 
       match InterruptHandler::guard(|| cmd.status()) {
         Ok(exit_status) => {
@@ -411,7 +417,7 @@ impl<'src, D> Recipe<'src, D> {
       command.args(positional);
     }
 
-    command.export(context.settings, dotenv, scope);
+    command.export(context.settings, dotenv, scope, context.unsets);
 
     // run it!
     match InterruptHandler::guard(|| command.status()) {

src/recipe_context.rs

@@ -5,4 +5,5 @@ pub(crate) struct RecipeContext<'src: 'run, 'run> {
   pub(crate) scope: &'run Scope<'src, 'run>,
   pub(crate) search: &'run Search,
   pub(crate) settings: &'run Settings<'src>,
+  pub(crate) unsets: &'run HashSet<String>,
 }

tests/export.rs

@@ -1,3 +1,5 @@
+use super::*;
+
 test! {
   name:     success,
   justfile: r#"
@@ -175,3 +177,38 @@ test! {
   stdout: "undefined\n",
   stderr: "echo $B\n",
 }
+
+#[test]
+fn unset_environment_variable_linewise() {
+  Test::new()
+    .justfile(
+      "
+     unset JUST_TEST_VARIABLE
+
+     recipe:
+         echo $JUST_TEST_VARIABLE
+      ",
+    )
+    .env("JUST_TEST_VARIABLE", "foo")
+    .stderr("echo $JUST_TEST_VARIABLE\nbash: line 1: JUST_TEST_VARIABLE: unbound variable\nerror: Recipe `recipe` failed on line 4 with exit code 127\n")
+    .status(127)
+    .run();
+}
+
+#[test]
+fn unset_environment_variable_shebang() {
+  Test::new()
+    .justfile(
+      "
+     unset JUST_TEST_VARIABLE
+
+     recipe:
+         #!/usr/bin/env bash
+         echo \"variable: $JUST_TEST_VARIABLE\"
+      ",
+    )
+    .env("JUST_TEST_VARIABLE", "foo")
+    .stdout("variable: \n")
+    .status(0)
+    .run();
+}