Hacks for usage with stable Rust

Cargo.toml

@@ -11,7 +11,7 @@ repository = "https://github.com/dhardy/kas"
 
 [features]
 # Enables usage of unstable Rust features
-nightly = []
+nightly = ["kas-macros/nightly"]
 
 [dependencies.kas-macros]
 version = "0.1.0-pre.1"
@@ -27,6 +27,10 @@ version = "0.8"
 version = "0.20.0-alpha5"
 optional = true
 
+[dependencies]
+proc-macro-hack = "0.5"
+proc-macro-nested = "0.1"
+
 [workspace]
 members = ["kas-macros", "kas-wgpu"]
 

kas-macros/Cargo.toml

@@ -12,9 +12,14 @@ repository = "https://github.com/dhardy/kas"
 [lib]
 proc-macro = true
 
+[features]
+# Enables usage of unstable Rust features
+nightly = []
+
 [dependencies]
 quote = "1.0"
 proc-macro2 = { version = "1.0", features = ["nightly"] }
+proc-macro-hack = "0.5"
 
 [dependencies.syn]
 version = "1.0"

kas-macros/src/args.rs

@@ -63,6 +63,7 @@ pub fn read_attrs(ast: &mut DeriveInput) -> Result<Args> {
                 if core.is_none() {
                     core = Some(member(i, field.ident.clone()));
                 } else {
+                    #[cfg(feature = "nightly")]
                     attr.span()
                         .unwrap()
                         .error("multiple fields marked with #[core]")
@@ -73,6 +74,7 @@ pub fn read_attrs(ast: &mut DeriveInput) -> Result<Args> {
                     if field.ty != parse_quote! { <Self as kas::LayoutData>::Data }
                         && field.ty != parse_quote! { <Self as LayoutData>::Data }
                     {
+                        #[cfg(feature = "nightly")]
                         field
                             .ty
                             .span()
@@ -82,6 +84,7 @@ pub fn read_attrs(ast: &mut DeriveInput) -> Result<Args> {
                     }
                     layout_data = Some(member(i, field.ident.clone()));
                 } else {
+                    #[cfg(feature = "nightly")]
                     attr.span()
                         .unwrap()
                         .error("multiple fields marked with #[layout_data]")
@@ -103,6 +106,7 @@ pub fn read_attrs(ast: &mut DeriveInput) -> Result<Args> {
             if widget.is_none() {
                 widget = Some(syn::parse2(attr.tokens)?);
             } else {
+                #[cfg(feature = "nightly")]
                 attr.span()
                     .unwrap()
                     .error("multiple #[widget(..)] attributes on type")
@@ -112,6 +116,7 @@ pub fn read_attrs(ast: &mut DeriveInput) -> Result<Args> {
             if handler.is_none() {
                 handler = Some(syn::parse2(attr.tokens)?);
             } else {
+                #[cfg(feature = "nightly")]
                 attr.span()
                     .unwrap()
                     .error("multiple #[handler(..)] attributes on type")

kas-macros/src/lib.rs

@@ -4,16 +4,18 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 #![recursion_limit = "128"]
-#![feature(proc_macro_diagnostic)]
+#![cfg_attr(feature = "nightly", feature(proc_macro_diagnostic))]
 
 extern crate proc_macro;
 
 mod args;
 
 use proc_macro2::{Span, TokenStream};
+use proc_macro_hack::proc_macro_hack;
 use quote::{quote, TokenStreamExt};
 use std::fmt::Write;
 use syn::punctuated::Punctuated;
+#[cfg(feature = "nightly")]
 use syn::spanned::Spanned;
 use syn::token::Comma;
 use syn::{parse_macro_input, parse_quote};
@@ -201,9 +203,7 @@ pub fn derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
 /// Macro to create a widget with anonymous type
 ///
 /// See the [`kas::macros`](../kas/macros/index.html) module documentation.
-///
-/// Currently usage of this macro requires `#![feature(proc_macro_hygiene)]`.
-#[proc_macro]
+#[proc_macro_hack]
 pub fn make_widget(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let mut find_handler_ty_buf: Vec<(Ident, Type)> = vec![];
     // find type of handler's message; return None on error
@@ -222,16 +222,19 @@ pub fn make_widget(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
         for impl_block in impls {
             for f in &impl_block.1 {
                 if f.sig.ident == *handler {
-                    if let Some(x) = x {
+                    if let Some(_x) = x {
+                        #[cfg(feature = "nightly")]
                         handler
                             .span()
                             .unwrap()
                             .error("multiple methods with this name")
                             .emit();
-                        x.0.span()
+                        #[cfg(feature = "nightly")]
+                        _x.0.span()
                             .unwrap()
                             .error("first method with this name")
                             .emit();
+                        #[cfg(feature = "nightly")]
                         f.sig
                             .ident
                             .span()
@@ -241,6 +244,7 @@ pub fn make_widget(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
                         return None;
                     }
                     if f.sig.inputs.len() != 3 {
+                        #[cfg(feature = "nightly")]
                         f.sig.span()
                             .unwrap()
                             .error("handler functions must have signature: fn handler(&mut self, tk: &mut dyn TkWindow, msg: T)")
@@ -260,6 +264,7 @@ pub fn make_widget(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
             find_handler_ty_buf.push((handler.clone(), x.1.clone()));
             Some(x.1)
         } else {
+            #[cfg(feature = "nightly")]
             handler
                 .span()
                 .unwrap()

kas-wgpu/examples/calculator.rs

@@ -4,17 +4,17 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Simple calculator example (lots of buttons, grid layout)
-#![feature(proc_macro_hygiene)]
+#![recursion_limit = "1024"]
 
 use std::num::ParseFloatError;
 use std::str::FromStr;
 
 use kas::class::HasText;
 use kas::event::VirtualKeyCode as VK;
 use kas::event::{Response, VoidMsg};
-use kas::macros::{make_widget, VoidMsg};
+use kas::macros::VoidMsg;
 use kas::widget::{EditBox, TextButton, Window};
-use kas::TkWindow;
+use kas::{make_widget, TkWindow};
 
 #[derive(Clone, Debug, VoidMsg)]
 enum Key {

kas-wgpu/examples/clock.rs

@@ -4,7 +4,6 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Clock example (simple periodically updated display)
-#![feature(proc_macro_hygiene)]
 
 extern crate chrono;
 
@@ -13,9 +12,8 @@ use std::time::Duration;
 
 use kas::class::HasText;
 use kas::event::{Callback, VoidMsg};
-use kas::macros::make_widget;
 use kas::widget::{Label, Window};
-use kas::{TkWindow, WidgetCore};
+use kas::{make_widget, TkWindow, WidgetCore};
 
 fn main() {
     let mut window = Window::new(

kas-wgpu/examples/clock_expanded.rs

@@ -4,7 +4,6 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Clock example, with the make_widget macro expanded
-#![feature(proc_macro_hygiene)]
 
 extern crate chrono;
 

kas-wgpu/examples/counter.rs

@@ -4,13 +4,13 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Counter example (simple button)
-#![feature(proc_macro_hygiene)]
+#![recursion_limit = "256"]
 
 use kas::class::HasText;
 use kas::event::{VoidMsg, VoidResponse};
-use kas::macros::{make_widget, VoidMsg};
+use kas::macros::VoidMsg;
 use kas::widget::{Label, TextButton, Window};
-use kas::TkWindow;
+use kas::{make_widget, TkWindow};
 
 #[derive(Clone, Debug, VoidMsg)]
 enum Message {

kas-wgpu/examples/dynamic.rs

@@ -4,14 +4,14 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Dynamic widget example
-#![feature(proc_macro_hygiene)]
+#![recursion_limit = "256"]
 
 use kas::class::HasText;
 use kas::event::{Callback, Response, VoidMsg};
 use kas::layout::Vertical;
-use kas::macros::{make_widget, VoidMsg};
+use kas::macros::VoidMsg;
 use kas::widget::{DynVec, EditBox, Label, ScrollRegion, TextButton, Window};
-use kas::TkWindow;
+use kas::{make_widget, TkWindow};
 
 #[derive(Clone, Debug, VoidMsg)]
 enum Control {

kas-wgpu/examples/gallery.rs

@@ -4,12 +4,12 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Gallery of all widgets
-#![feature(proc_macro_hygiene)]
+#![recursion_limit = "512"]
 
 use kas::event::{VoidMsg, VoidResponse};
-use kas::macros::{make_widget, VoidMsg};
+use kas::macros::VoidMsg;
 use kas::widget::*;
-use kas::TkWindow;
+use kas::{make_widget, TkWindow};
 
 #[derive(Clone, Debug, VoidMsg)]
 enum Item {

kas-wgpu/examples/layout.rs

@@ -4,10 +4,10 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Gallery of all widgets
-#![feature(proc_macro_hygiene)]
+#![recursion_limit = "256"]
 
 use kas::event::VoidMsg;
-use kas::macros::make_widget;
+use kas::make_widget;
 use kas::widget::{CheckBox, EditBox, Label, Window};
 
 fn main() -> Result<(), winit::error::OsError> {

kas-wgpu/examples/stopwatch.rs

@@ -4,16 +4,16 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Counter example (simple button)
-#![feature(proc_macro_hygiene)]
+#![recursion_limit = "512"]
 
 use std::fmt::Write;
 use std::time::{Duration, Instant};
 
 use kas::class::HasText;
 use kas::event::{Callback, Response, VoidMsg};
-use kas::macros::{make_widget, VoidMsg};
+use kas::macros::VoidMsg;
 use kas::widget::{Label, TextButton, Window};
-use kas::TkWindow;
+use kas::{make_widget, TkWindow};
 
 #[derive(Clone, Debug, VoidMsg)]
 enum Control {

kas-wgpu/examples/theme.rs

@@ -4,16 +4,16 @@
 //     https://www.apache.org/licenses/LICENSE-2.0
 
 //! Custom theme demo
-#![feature(proc_macro_hygiene)]
+#![recursion_limit = "256"]
 
 use std::cell::Cell;
 
 use kas::draw::Colour;
 use kas::event::{VoidMsg, VoidResponse};
-use kas::macros::{make_widget, VoidMsg};
+use kas::macros::VoidMsg;
 use kas::theme::Theme;
 use kas::widget::*;
-use kas::TkWindow;
+use kas::{make_widget, TkWindow};
 
 use kas_wgpu::draw::*;
 use kas_wgpu::glyph::Font;

src/lib.rs

@@ -45,3 +45,9 @@ pub mod macros;
 pub use crate::data::*;
 pub use crate::toolkit::*;
 pub use crate::traits::*;
+
+use proc_macro_hack::proc_macro_hack;
+
+/// See [The `make_widget` macro]: #the-make_widget-macro
+#[proc_macro_hack(support_nested)]
+pub use kas_macros::make_widget;

src/macros.rs

@@ -21,12 +21,6 @@
 //! because procedural macros must be defined in a special crate. The
 //! `kas-macros` crate should not be used directly.
 //!
-//! Note further that these macros require gated functionality only available
-//! in nightly `rustc` builds:
-//! ```
-//! #![feature(proc_macro_hygiene)]
-//! ```
-//!
 //! [`make_widget`]: #the-make_widget-macro
 //! [`derive(Widget)`]: #the-derivewidget-macro
 //! [`derive(VoidMsg)`]: #the-derivevoidmsg-macro
@@ -215,9 +209,7 @@
 //! ### Example
 //!
 //! ```
-//! #![feature(proc_macro_hygiene)]
-//!
-//! use kas::macros::{make_widget};
+//! use kas::make_widget;
 //! use kas::widget::TextButton;
 //!
 //! #[derive(Copy, Clone, Debug)]
@@ -257,4 +249,4 @@
 //! [`Handler`]: crate::event::Handler
 //! [`Handler::Msg`]: crate::event::Handler::Msg
 
-pub use kas_macros::{make_widget, VoidMsg, Widget};
+pub use kas_macros::{VoidMsg, Widget};