Require set fallback := true to enable recipe fallback (#1368)

GRAMMAR.md

@@ -62,6 +62,7 @@ export        : 'export' assignment
 setting       : 'set' 'dotenv-load' boolean?
               | 'set' 'ignore-comments' boolean?
               | 'set' 'export' boolean?
+              | 'set' 'fallback' boolean?
               | 'set' 'positional-arguments' boolean?
               | 'set' 'allow-duplicate-recipes' boolean?
               | 'set' 'windows-powershell' boolean?

README.md

@@ -646,6 +646,7 @@ foo:
 | `allow-duplicate-recipes` | boolean            | False   | Allow recipes appearing later in a `justfile` to override earlier recipes with the same name. |
 | `dotenv-load`             | boolean            | False   | Load a `.env` file, if present.                                                               |
 | `export`                  | boolean            | False   | Export all variables as environment variables.                                                |
+| `fallback`                | boolean            | False   | Search `justfile` in parent directory if the first recipe on the command line is not found.   |
 | `ignore-comments`         | boolean            | False   | Ignore recipe lines beginning with `#`.                                                       |
 | `positional-arguments`    | boolean            | False   | Pass positional arguments.                                                                    |
 | `shell`                   | `[COMMAND, ARGS…]` | -       | Set the command used to invoke recipes and evaluate backticks.                                |
@@ -2063,15 +2064,18 @@ The `--dump` command can be used with `--dump-format json` to print a JSON repre
 
 ### Falling back to parent `justfile`s
 
-If a recipe is not found, `just` will look for `justfile`s in the parent
-directory and up, until it reaches the root directory.
+If a recipe is not found in a `justfile` and the `fallback` setting is set,
+`just` will look for `justfile`s in the parent directory and up, until it
+reaches the root directory. `just` will stop after it reaches a `justfile` in
+which the `fallback` setting is `false` or unset.
 
 This feature is currently unstable, and so must be enabled with the
 `--unstable` flag.
 
 As an example, suppose the current directory contains this `justfile`:
 
 ```make
+set fallback
 foo:
   echo foo
 ```

src/analyzer.rs

@@ -53,6 +53,9 @@ impl<'src> Analyzer<'src> {
         Setting::Export(export) => {
           settings.export = export;
         }
+        Setting::Fallback(fallback) => {
+          settings.fallback = fallback;
+        }
         Setting::IgnoreComments(ignore_comments) => {
           settings.ignore_comments = ignore_comments;
         }

src/keyword.rs

@@ -8,6 +8,7 @@ pub(crate) enum Keyword {
   DotenvLoad,
   Else,
   Export,
+  Fallback,
   False,
   If,
   IgnoreComments,

src/node.rs

@@ -227,6 +227,7 @@ impl<'src> Node<'src> for Set<'src> {
       Setting::AllowDuplicateRecipes(value)
       | Setting::DotenvLoad(value)
       | Setting::Export(value)
+      | Setting::Fallback(value)
       | Setting::PositionalArguments(value)
       | Setting::WindowsPowerShell(value)
       | Setting::IgnoreComments(value) => {

src/parser.rs

@@ -761,8 +761,9 @@ impl<'tokens, 'src> Parser<'tokens, 'src> {
           Some(Setting::AllowDuplicateRecipes(self.parse_set_bool()?))
         }
         Keyword::DotenvLoad => Some(Setting::DotenvLoad(self.parse_set_bool()?)),
-        Keyword::IgnoreComments => Some(Setting::IgnoreComments(self.parse_set_bool()?)),
         Keyword::Export => Some(Setting::Export(self.parse_set_bool()?)),
+        Keyword::Fallback => Some(Setting::Fallback(self.parse_set_bool()?)),
+        Keyword::IgnoreComments => Some(Setting::IgnoreComments(self.parse_set_bool()?)),
         Keyword::PositionalArguments => Some(Setting::PositionalArguments(self.parse_set_bool()?)),
         Keyword::WindowsPowershell => Some(Setting::WindowsPowerShell(self.parse_set_bool()?)),
         _ => None,

src/setting.rs

@@ -4,8 +4,9 @@ use super::*;
 pub(crate) enum Setting<'src> {
   AllowDuplicateRecipes(bool),
   DotenvLoad(bool),
-  IgnoreComments(bool),
   Export(bool),
+  Fallback(bool),
+  IgnoreComments(bool),
   PositionalArguments(bool),
   Shell(Shell<'src>),
   WindowsPowerShell(bool),
@@ -17,8 +18,9 @@ impl<'src> Display for Setting<'src> {
     match self {
       Setting::AllowDuplicateRecipes(value)
       | Setting::DotenvLoad(value)
-      | Setting::IgnoreComments(value)
       | Setting::Export(value)
+      | Setting::Fallback(value)
+      | Setting::IgnoreComments(value)
       | Setting::PositionalArguments(value)
       | Setting::WindowsPowerShell(value) => write!(f, "{}", value),
       Setting::Shell(shell) | Setting::WindowsShell(shell) => write!(f, "{}", shell),

src/settings.rs

@@ -10,6 +10,7 @@ pub(crate) struct Settings<'src> {
   pub(crate) allow_duplicate_recipes: bool,
   pub(crate) dotenv_load: Option<bool>,
   pub(crate) export: bool,
+  pub(crate) fallback: bool,
   pub(crate) ignore_comments: bool,
   pub(crate) positional_arguments: bool,
   pub(crate) shell: Option<Shell<'src>>,

src/subcommand.rs

@@ -135,7 +135,7 @@ impl Subcommand {
         };
 
         match Self::run_inner(config, loader, arguments, overrides, &search) {
-          Err(err @ Error::UnknownRecipes { .. }) => {
+          Err((err @ Error::UnknownRecipes { .. }, true)) => {
             match search.justfile.parent().unwrap().parent() {
               Some(parent) => {
                 unknown_recipes_errors.get_or_insert(err);
@@ -144,7 +144,7 @@ impl Subcommand {
               None => return Err(err),
             }
           }
-          result => return result,
+          result => return result.map_err(|(err, _fallback)| err),
         }
       }
     } else {
@@ -155,6 +155,7 @@ impl Subcommand {
         overrides,
         &Search::find(&config.search_config, &config.invocation_directory)?,
       )
+      .map_err(|(err, _fallback)| err)
     }
   }
 
@@ -164,9 +165,12 @@ impl Subcommand {
     arguments: &[String],
     overrides: &BTreeMap<String, String>,
     search: &Search,
-  ) -> Result<(), Error<'src>> {
-    let (_src, _ast, justfile) = Self::compile(config, loader, search)?;
-    justfile.run(config, search, overrides, arguments)
+  ) -> Result<(), (Error<'src>, bool)> {
+    let (_src, _ast, justfile) =
+      Self::compile(config, loader, search).map_err(|err| (err, false))?;
+    justfile
+      .run(config, search, overrides, arguments)
+      .map_err(|err| (err, justfile.settings.fallback))
   }
 
   fn compile<'src>(

tests/fall_back_to_parent.rs

@@ -6,6 +6,40 @@ fn runs_recipe_in_parent_if_not_found_in_current() {
     .tree(tree! {
       bar: {
         justfile: "
+          set fallback
+
+          baz:
+            echo subdir
+        "
+      }
+    })
+    .justfile(
+      "
+      foo:
+        echo root
+    ",
+    )
+    .args(&["--unstable", "foo"])
+    .current_dir("bar")
+    .stderr(format!(
+      "
+      Trying ..{}justfile
+      echo root
+    ",
+      MAIN_SEPARATOR
+    ))
+    .stdout("root\n")
+    .run();
+}
+
+#[test]
+fn setting_accepts_value() {
+  Test::new()
+    .tree(tree! {
+      bar: {
+        justfile: "
+          set fallback := true
+
           baz:
             echo subdir
         "
@@ -36,6 +70,8 @@ fn print_error_from_parent_if_recipe_not_found_in_current() {
     .tree(tree! {
       bar: {
         justfile: "
+          set fallback
+
           baz:
             echo subdir
         "
@@ -64,6 +100,8 @@ fn requires_unstable() {
     .tree(tree! {
       bar: {
         justfile: "
+          set fallback
+
           baz:
             echo subdir
         "
@@ -82,19 +120,47 @@ fn requires_unstable() {
     .run();
 }
 
+#[test]
+fn requires_setting() {
+  Test::new()
+    .tree(tree! {
+      bar: {
+        justfile: "
+          baz:
+            echo subdir
+        "
+      }
+    })
+    .justfile(
+      "
+      foo:
+        echo root
+    ",
+    )
+    .args(&["--unstable", "foo"])
+    .current_dir("bar")
+    .status(EXIT_FAILURE)
+    .stderr("error: Justfile does not contain recipe `foo`.\n")
+    .run();
+}
+
 #[test]
 fn works_with_provided_search_directory() {
   Test::new()
     .tree(tree! {
       bar: {
         justfile: "
+          set fallback
+
           baz:
             echo subdir
         "
       }
     })
     .justfile(
       "
+      set fallback
+
       foo:
         echo root
     ",
@@ -118,13 +184,17 @@ fn doesnt_work_with_justfile() {
     .tree(tree! {
       bar: {
         justfile: "
+          set fallback
+
           baz:
             echo subdir
         "
       }
     })
     .justfile(
       "
+      set fallback
+
       foo:
         echo root
     ",
@@ -142,13 +212,17 @@ fn doesnt_work_with_justfile_and_working_directory() {
     .tree(tree! {
       bar: {
         justfile: "
+          set fallback
+
           baz:
             echo subdir
         "
       }
     })
     .justfile(
       "
+      set fallback
+
       foo:
         echo root
     ",
@@ -173,6 +247,8 @@ fn prints_correct_error_message_when_recipe_not_found() {
     .tree(tree! {
       bar: {
         justfile: "
+          set fallback
+
           bar:
             echo subdir
         "
@@ -196,3 +272,82 @@ fn prints_correct_error_message_when_recipe_not_found() {
     ))
     .run();
 }
+
+#[test]
+fn multiple_levels_of_fallback_work() {
+  Test::new()
+    .tree(tree! {
+      a: {
+        b: {
+          justfile: "
+            set fallback
+
+            foo:
+              echo subdir
+          "
+        },
+        justfile: "
+          set fallback
+
+          bar:
+            echo subdir
+        "
+      }
+    })
+    .justfile(
+      "
+      baz:
+        echo root
+    ",
+    )
+    .args(&["--unstable", "baz"])
+    .current_dir("a/b")
+    .stdout("root\n")
+    .stderr(format!(
+      "
+      Trying ..{}justfile
+      Trying ..{}..{}justfile
+      echo root
+    ",
+      MAIN_SEPARATOR, MAIN_SEPARATOR, MAIN_SEPARATOR
+    ))
+    .run();
+}
+
+#[test]
+fn stop_fallback_when_fallback_is_false() {
+  Test::new()
+    .tree(tree! {
+      a: {
+        b: {
+          justfile: "
+            set fallback
+            foo:
+              echo subdir
+          "
+        },
+        justfile: "
+          bar:
+            echo subdir
+        "
+      }
+    })
+    .justfile(
+      "
+      baz:
+        echo root
+    ",
+    )
+    .args(&["--unstable", "baz"])
+    .current_dir("a/b")
+    .stderr(format!(
+      "
+      Trying ..{}justfile
+      error: Justfile does not contain recipe `baz`.
+      Did you mean `bar`?
+    ",
+      MAIN_SEPARATOR
+    ))
+    .status(EXIT_FAILURE)
+    .run();
+}