Auto merge of #80867 - JohnTitor:rollup-tvqw555, r=JohnTitor

Rollup of 9 pull requests

Successful merges:

 - #79502 (Implement From<char> for u64 and u128.)
 - #79968 (Improve core::ptr::drop_in_place debuginfo)
 - #80774 (Fix safety comment)
 - #80801 (Use correct span for structured suggestion)
 - #80803 (Remove useless `fill_in` function)
 - #80820 (Support `download-ci-llvm` on NixOS)
 - #80825 (Remove under-used ImplPolarity enum)
 - #80850 (Allow #[rustc_builtin_macro = "name"])
 - #80857 (Add comment to `Vec::truncate` explaining `>` vs `>=`)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 3 insertions, 1 deletions

diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index fefc0cb48dd..6635d44496c 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -671,7 +671,9 @@ impl SourceMap {
             let pat = pat.to_owned() + ws;
             if let Ok(prev_source) = self.span_to_prev_source(sp) {
                 let prev_source = prev_source.rsplit(&pat).next().unwrap_or("").trim_start();
-                if !prev_source.is_empty() && (!prev_source.contains('\n') || accept_newlines) {
+                if prev_source.is_empty() && sp.lo().0 != 0 {
+                    return sp.with_lo(BytePos(sp.lo().0 - 1));
+                } else if !prev_source.contains('\n') || accept_newlines {
                     return sp.with_lo(BytePos(sp.lo().0 - prev_source.len() as u32));
                 }
             }