Add suggestions to mention sourcing env.fish

src/cli/self_update.rs

@@ -215,24 +215,33 @@ but will not be added automatically."
     };
 }
 
+#[cfg(not(windows))]
+macro_rules! post_install_msg_unix_source_env {
+    () => {
+        r#"To configure your current shell, you need to source
+the corresponding `env` file under {cargo_home}.
+
+This is usually done by running one of the following:
+    source "{cargo_home}/env"        # For bash/zsh
+    . "{cargo_home}/env"             # For ash/dash/pdksh (note the leading DOT)
+    source "{cargo_home}/env.fish"   # For fish
+"#
+    };
+}
+
 #[cfg(not(windows))]
 macro_rules! post_install_msg_unix {
     () => {
-        r#"# Rust is installed now. Great!
+        concat!(
+            r"# Rust is installed now. Great!
 
 To get started you may need to restart your current shell.
 This would reload your `PATH` environment variable to include
 Cargo's bin directory ({cargo_home}/bin).
 
-To configure your current shell, you need to source
-the `env` file ({cargo_home}/env).
-
-This is usually done by running:
-    source "{cargo_home}/env"
-
-The `source` command above might need to be replaced with `.`
-on shells like `ash`, `dash` and `pdksh`.
-"#
+",
+            post_install_msg_unix_source_env!(),
+        )
     };
 }
 
@@ -252,20 +261,15 @@ Cargo's bin directory ({cargo_home}\\bin).
 #[cfg(not(windows))]
 macro_rules! post_install_msg_unix_no_modify_path {
     () => {
-        r#"# Rust is installed now. Great!
+        concat!(
+            r"# Rust is installed now. Great!
 
 To get started you need Cargo's bin directory ({cargo_home}/bin) in your `PATH`
 environment variable. This has not been done automatically.
 
-To configure your current shell, you need to source
-the `env` file ({cargo_home}/env).
-
-This is usually done by running:
-    source "{cargo_home}/env"
-
-The `source` command above might need to be replaced with `.`
-on shells like `ash`, `dash` and `pdksh`.
-"#
+",
+            post_install_msg_unix_source_env!(),
+        )
     };
 }
 

src/cli/self_update/shell.rs

@@ -212,7 +212,7 @@ impl UnixShell for Fish {
     fn does_exist(&self) -> bool {
         // fish has to either be the shell or be callable for fish setup.
         matches!(process().var("SHELL"), Ok(sh) if sh.contains("fish"))
-            || matches!(utils::find_cmd(&["fish"]), Some(_))
+            || utils::find_cmd(&["fish"]).is_some()
     }
 
     // > "$XDG_CONFIG_HOME/fish/conf.d" (or "~/.config/fish/conf.d" if that variable is unset) for the user