Merge #37

37: Fix parsing of macro metavariable in attribute arguments r=taiki-e a=taiki-e



Co-authored-by: Taiki Endo <[email protected]>

CHANGELOG.md

@@ -10,6 +10,8 @@ Note: In this file, do not use the hard wrap in the middle of a sentence for com
 
 ## [Unreleased]
 
+- [Fix parsing of macro metavariable in attribute arguments.](https://github.com/taiki-e/const_fn/pull/37)
+
 ## [0.4.7] - 2021-04-17
 
 - [Support compiling with `RUSTFLAGS='-Z assume-incomplete-release'` on nightly compiler.](https://github.com/taiki-e/const_fn/pull/35)

src/lib.rs

@@ -84,6 +84,7 @@ use proc_macro::{Delimiter, TokenStream, TokenTree};
 use crate::{
     ast::{Func, LitStr},
     error::Error,
+    iter::TokenIter,
     to_tokens::ToTokens,
     utils::{cfg_attrs, parse_as_empty, tt_span},
 };
@@ -155,7 +156,7 @@ enum Arg {
 }
 
 fn parse_arg(tokens: TokenStream) -> Result<Arg> {
-    let mut iter = tokens.into_iter();
+    let mut iter = TokenIter::new(tokens);
 
     let next = iter.next();
     let next_span = tt_span(next.as_ref());

test_suite/tests/test.rs

@@ -240,3 +240,21 @@ pub mod cfg {
         assert_eq!(A::const_unstable(const_vec_new::<u8>()), A(Vec::new()));
     }
 }
+
+pub mod macros {
+    #![allow(dead_code)]
+
+    use const_fn::const_fn;
+
+    macro_rules! args {
+        ($args:expr) => {
+            #[const_fn($args)]
+            const fn args<T>(x: T) -> T {
+                x
+            }
+        };
+    }
+
+    args!("1.31");
+    const _: () = args(());
+}