Merge 1.x (1.0.69) into 2.x (master)

Author: dtolnay

impl/src/fmt.rs

@@ -2,7 +2,7 @@ use crate::ast::{ContainerKind, Field};
 use crate::attr::{Display, Trait};
 use crate::scan_expr::scan_expr;
 use crate::unraw::{IdentUnraw, MemberUnraw};
-use proc_macro2::{Delimiter, TokenStream};
+use proc_macro2::{Delimiter, TokenStream, TokenTree};
 use quote::{format_ident, quote, quote_spanned};
 use std::collections::{BTreeSet, HashMap, HashSet};
 use std::iter;
@@ -225,6 +225,8 @@ fn fallback_explicit_named_args(input: ParseStream) -> Result<FmtArguments> {
             let ident: IdentUnraw = input.parse()?;
             input.parse::<Token![=]>()?;
             args.named.insert(ident);
+        } else {
+            input.parse::<TokenTree>()?;
         }
     }
 

tests/ui/expression-fallback.rs

@@ -0,0 +1,7 @@
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+#[error("".yellow)]
+pub struct ArgError;
+
+fn main() {}

tests/ui/expression-fallback.stderr

@@ -0,0 +1,19 @@
+error: expected `,`, found `.`
+ --> tests/ui/expression-fallback.rs:4:11
+  |
+4 | #[error("".yellow)]
+  |           ^ expected `,`
+
+error: argument never used
+ --> tests/ui/expression-fallback.rs:4:12
+  |
+4 | #[error("".yellow)]
+  |         -- ^^^^^^ argument never used
+  |         |
+  |         formatting specifier missing
+
+error[E0425]: cannot find value `yellow` in this scope
+ --> tests/ui/expression-fallback.rs:4:12
+  |
+4 | #[error("".yellow)]
+  |            ^^^^^^ not found in this scope