Revert "Improve heuristics whether `format_args` string is a source literal"

This reverts commit e6c02aad9345925cfed74f86b414c4d0715d381b.

Keeps the code improvements from the PR and the test (as a known-bug).

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/ui/fmt/auxiliary/format-string-proc-macro.rs b/tests/ui/fmt/auxiliary/format-string-proc-macro.rs
index 539c8fb27b3..1b7ef93f41d 100644
--- a/tests/ui/fmt/auxiliary/format-string-proc-macro.rs
+++ b/tests/ui/fmt/auxiliary/format-string-proc-macro.rs
@@ -28,6 +28,7 @@ pub fn err_with_input_span(input: TokenStream) -> TokenStream {
     TokenStream::from(TokenTree::Literal(lit))
 }
 
+
 #[proc_macro]
 pub fn respan_to_invalid_format_literal(input: TokenStream) -> TokenStream {
     let mut s = Literal::string("{");
@@ -38,3 +39,14 @@ pub fn respan_to_invalid_format_literal(input: TokenStream) -> TokenStream {
         TokenTree::from(Group::new(Delimiter::Parenthesis, TokenTree::from(s).into())),
     ])
 }
+
+#[proc_macro]
+pub fn capture_a_with_prepended_space_preserve_span(input: TokenStream) -> TokenStream {
+    let mut s = Literal::string(" {a}");
+    s.set_span(input.into_iter().next().unwrap().span());
+    TokenStream::from_iter([
+        TokenTree::from(Ident::new("format", Span::call_site())),
+        TokenTree::from(Punct::new('!', Spacing::Alone)),
+        TokenTree::from(Group::new(Delimiter::Parenthesis, TokenTree::from(s).into())),
+    ])
+}