From 4ac60601d32d96688494c4bb404a04205501a02b Mon Sep 17 00:00:00 2001
From: surechen <chenshuo17@huawei.com>
Date: Thu, 25 Jul 2024 22:33:45 +0800
Subject: [PATCH] Fix a span error when parsing a wrong param of function.

fixes #128042
---
 compiler/rustc_parse/src/parser/item.rs       |  9 +++++++-
 .../suggest-add-self-issue-128042.rs          | 12 ++++++++++
 .../suggest-add-self-issue-128042.stderr      | 22 +++++++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/suggestions/suggest-add-self-issue-128042.rs
 create mode 100644 tests/ui/suggestions/suggest-add-self-issue-128042.stderr

diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index fbc5b914600..9aaf4b99243 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -2773,7 +2773,14 @@ pub(super) fn parse_fn_params(&mut self, req_name: ReqName) -> PResult<'a, ThinV
             let snapshot = p.create_snapshot_for_diagnostic();
             let param = p.parse_param_general(req_name, first_param).or_else(|e| {
                 let guar = e.emit();
-                let lo = p.prev_token.span;
+                // When parsing a param failed, we should check to make the span of the param
+                // not contain '(' before it.
+                // For example when parsing `*mut Self` in function `fn oof(*mut Self)`.
+                let lo = if let TokenKind::OpenDelim(Delimiter::Parenthesis) = p.prev_token.kind {
+                    p.prev_token.span.shrink_to_hi()
+                } else {
+                    p.prev_token.span
+                };
                 p.restore_snapshot(snapshot);
                 // Skip every token until next possible arg or end.
                 p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(Delimiter::Parenthesis)]);
diff --git a/tests/ui/suggestions/suggest-add-self-issue-128042.rs b/tests/ui/suggestions/suggest-add-self-issue-128042.rs
new file mode 100644
index 00000000000..f94d166c496
--- /dev/null
+++ b/tests/ui/suggestions/suggest-add-self-issue-128042.rs
@@ -0,0 +1,12 @@
+struct Thing {
+    state: u8,
+}
+
+impl Thing {
+    fn oof(*mut Self) { //~ ERROR expected parameter name, found `*`
+        self.state = 1;
+        //~^ ERROR expected value, found module `self`
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/suggestions/suggest-add-self-issue-128042.stderr b/tests/ui/suggestions/suggest-add-self-issue-128042.stderr
new file mode 100644
index 00000000000..49ac1563250
--- /dev/null
+++ b/tests/ui/suggestions/suggest-add-self-issue-128042.stderr
@@ -0,0 +1,22 @@
+error: expected parameter name, found `*`
+  --> $DIR/suggest-add-self-issue-128042.rs:6:12
+   |
+LL |     fn oof(*mut Self) {
+   |            ^ expected parameter name
+
+error[E0424]: expected value, found module `self`
+  --> $DIR/suggest-add-self-issue-128042.rs:7:9
+   |
+LL |     fn oof(*mut Self) {
+   |        --- this function doesn't have a `self` parameter
+LL |         self.state = 1;
+   |         ^^^^ `self` value is a keyword only available in methods with a `self` parameter
+   |
+help: add a `self` receiver parameter to make the associated `fn` a method
+   |
+LL |     fn oof(&self, *mut Self) {
+   |            ++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0424`.