windows: Fix rust tasks (#13413)

https://github.com/zed-industries/zed/assets/14981363/56c208da-132c-438a-92b3-e31505859262


Release Notes:

- N/A

crates/terminal/src/terminal_settings.rs

@@ -268,6 +268,48 @@ pub enum Shell {
     },
 }
 
+impl Shell {
+    pub fn retrieve_system_shell() -> Option<String> {
+        #[cfg(not(target_os = "windows"))]
+        {
+            use anyhow::Context;
+            use util::ResultExt;
+
+            return std::env::var("SHELL")
+                .context("Error finding SHELL in env.")
+                .log_err();
+        }
+        // `alacritty_terminal` uses this as default on Windows. See:
+        // https://github.com/alacritty/alacritty/blob/0d4ab7bca43213d96ddfe40048fc0f922543c6f8/alacritty_terminal/src/tty/windows/mod.rs#L130
+        #[cfg(target_os = "windows")]
+        return Some("powershell".to_owned());
+    }
+
+    /// Convert unix-shell variable syntax to windows-shell syntax.
+    /// `powershell` and `cmd` are considered valid here.
+    #[cfg(target_os = "windows")]
+    pub fn to_windows_shell_variable(shell_type: WindowsShellType, input: String) -> String {
+        match shell_type {
+            WindowsShellType::Powershell => to_powershell_variable(input),
+            WindowsShellType::Cmd => to_cmd_variable(input),
+            WindowsShellType::Other => input,
+        }
+    }
+
+    #[cfg(target_os = "windows")]
+    pub fn to_windows_shell_type(shell: &str) -> WindowsShellType {
+        if shell == "powershell" || shell.ends_with("powershell.exe") {
+            WindowsShellType::Powershell
+        } else if shell == "cmd" || shell.ends_with("cmd.exe") {
+            WindowsShellType::Cmd
+        } else {
+            // Someother shell detected, the user might install and use a
+            // unix-like shell.
+            WindowsShellType::Other
+        }
+    }
+}
+
 #[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq, Eq, JsonSchema)]
 #[serde(rename_all = "snake_case")]
 pub enum AlternateScroll {
@@ -299,3 +341,55 @@ pub struct ToolbarContent {
     /// Default: true
     pub title: Option<bool>,
 }
+
+#[cfg(target_os = "windows")]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum WindowsShellType {
+    Powershell,
+    Cmd,
+    Other,
+}
+
+/// Convert `${SOME_VAR}`, `$SOME_VAR` to `%SOME_VAR%`.
+#[inline]
+#[cfg(target_os = "windows")]
+fn to_cmd_variable(input: String) -> String {
+    if let Some(var_str) = input.strip_prefix("${") {
+        if var_str.find(':').is_none() {
+            // If the input starts with "${", remove the trailing "}"
+            format!("%{}%", &var_str[..var_str.len() - 1])
+        } else {
+            // `${SOME_VAR:-SOME_DEFAULT}`, we currently do not handle this situation,
+            // which will result in the task failing to run in such cases.
+            input
+        }
+    } else if let Some(var_str) = input.strip_prefix('$') {
+        // If the input starts with "$", directly append to "$env:"
+        format!("%{}%", var_str)
+    } else {
+        // If no prefix is found, return the input as is
+        input
+    }
+}
+
+/// Convert `${SOME_VAR}`, `$SOME_VAR` to `$env:SOME_VAR`.
+#[inline]
+#[cfg(target_os = "windows")]
+fn to_powershell_variable(input: String) -> String {
+    if let Some(var_str) = input.strip_prefix("${") {
+        if var_str.find(':').is_none() {
+            // If the input starts with "${", remove the trailing "}"
+            format!("$env:{}", &var_str[..var_str.len() - 1])
+        } else {
+            // `${SOME_VAR:-SOME_DEFAULT}`, we currently do not handle this situation,
+            // which will result in the task failing to run in such cases.
+            input
+        }
+    } else if let Some(var_str) = input.strip_prefix('$') {
+        // If the input starts with "$", directly append to "$env:"
+        format!("$env:{}", var_str)
+    } else {
+        // If no prefix is found, return the input as is
+        input
+    }
+}