Add safe attribute helper to SafeDebug (Azure#2613)

* Add safe attribute helper to SafeDebug

* Require parenthesis

They should've been before, but I realized I wasn't propagating the errors up and had to make significant changes to do so.

* Always use inner-most safe attribute

Also updated docs.

* Fix MSRV test

Author: heaths

sdk/typespec/typespec_client_core/src/fmt.rs

@@ -5,31 +5,6 @@
 
 use std::borrow::Cow;
 
-/// Derive to help prevent leaking personally identifiable information (PII) that deriving [`Debug`](std::fmt::Debug) might otherwise.
-///
-/// `SafeDebug` is not a trait and cannot be implemented, nor should you derive `Debug` explicitly.
-/// Only when you derive `SafeDebug` will types help prevent leaking PII because, by default, only the type name is printed.
-/// Only when you import `typespec_client_core` with feature `debug` will it derive `Debug` normally.
-///
-/// # Examples
-///
-/// ```
-/// use typespec_client_core::fmt::SafeDebug;
-///
-/// #[derive(SafeDebug)]
-/// struct MyModel {
-///     name: Option<String>,
-/// }
-///
-/// let model = MyModel {
-///     name: Some("Kelly Smith".to_string()),
-/// };
-/// if cfg!(feature = "debug") {
-///     assert_eq!(format!("{model:?}"), r#"MyModel { name: Some("Kelly Smith") }"#);
-/// } else {
-///     assert_eq!(format!("{model:?}"), "MyModel { .. }");
-/// }
-/// ```
 #[cfg(feature = "derive")]
 pub use typespec_macros::SafeDebug;
 

sdk/typespec/typespec_macros/src/lib.rs

@@ -91,25 +91,66 @@ pub fn derive_model(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
 /// Only when you derive `SafeDebug` will types help prevent leaking PII because, by default, only the type name is printed.
 /// Only when you enable the `debug` feature will it derive `Debug` normally.
 ///
+/// You can attribute types, fields, and variants with `#[safe(true)]` or `#[safe(false)]` to optionally show or hide members.
+/// The default is that no members are shown. The inner most `#[safe(..)]` attribute determines whether to show or hide a member.
+///
 /// # Examples
 ///
 /// ```
 /// # use typespec_macros::SafeDebug;
 /// #[derive(SafeDebug)]
-/// struct MyModel {
-///     name: Option<String>,
+/// struct Person {
+///     name: String,
+/// }
+///
+/// let person = Person {
+///     name: "Kelly Smith".to_string(),
+/// };
+/// if cfg!(feature = "debug") {
+///     assert_eq!(format!("{person:?}"), r#"Person { name: "Kelly Smith" }"#);
+/// } else {
+///     assert_eq!(format!("{person:?}"), "Person { .. }");
+/// }
+/// ```
+///
+/// Using the `#[safe(..)]` attribute, you can selectively show or hide members.
+/// The default, when not present or inherited, is to always hide members unless the `debug` feature is enabled.
+///
+/// ```
+/// # use typespec_macros::SafeDebug;
+/// use std::ops::Range;
+///
+/// #[derive(SafeDebug)]
+/// struct Employee {
+///     name: String,
+///     #[safe(true)]
+///     position: Position,
+/// }
+///
+/// #[derive(SafeDebug)]
+/// #[safe(true)]
+/// struct Position {
+///     id: i32,
+///     title: String,
+///     #[safe(false)]
+///     salary: Range<i32>,
 /// }
 ///
-/// let model = MyModel {
-///     name: Some("Kelly Smith".to_string()),
+/// let employee = Employee {
+///     name: "Kelly Smith".to_string(),
+///     position: Position {
+///         id: 12,
+///         title: "Staff Engineer".to_string(),
+///         salary: 200_000..250_000,
+///     },
 /// };
 /// if cfg!(feature = "debug") {
-///     assert_eq!(format!("{model:?}"), r#"MyModel { name: Some("Kelly Smith") }"#);
+///     assert_eq!(format!("{employee:?}"), r#"Employee { name: "Kelly Smith", position: Position { id: 12, title: "Staff Engineer", salary: 200000..250000 } }"#);
 /// } else {
-///     assert_eq!(format!("{model:?}"), "MyModel { .. }");
+///     assert_eq!(format!("{employee:?}"), r#"Employee { position: Position { id: 12, title: "Staff Engineer", .. }, .. }"#);
 /// }
 /// ```
-#[proc_macro_derive(SafeDebug)]
+#[proc_macro_derive(SafeDebug, attributes(safe))]
 pub fn derive_safe_debug(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     run_derive_macro(input, safe_debug::derive_safe_debug_impl)
 }