From d60d5e8bde9650f967f511f6649bc8f8ece8decc Mon Sep 17 00:00:00 2001
From: Alex Macleod <alex@macleod.io>
Date: Sun, 24 Jul 2022 16:37:08 +0000
Subject: [PATCH] Fix `useless_format` spans for `format!("{foo}")`

---
 clippy_lints/src/format.rs | 19 ++-----------------
 tests/ui/format.fixed      |  6 ++++++
 tests/ui/format.rs         |  6 ++++++
 tests/ui/format.stderr     | 14 +++++++++++++-
 4 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/clippy_lints/src/format.rs b/clippy_lints/src/format.rs
index 3084c70589f..9137d8ef382 100644
--- a/clippy_lints/src/format.rs
+++ b/clippy_lints/src/format.rs
@@ -9,7 +9,7 @@
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::symbol::kw;
-use rustc_span::{sym, BytePos, Span};
+use rustc_span::{sym, Span};
 
 declare_clippy_lint! {
     /// ### What it does
@@ -85,22 +85,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
                         ExprKind::MethodCall(path, ..) => path.ident.name.as_str() == "to_string",
                         _ => false,
                     };
-                    let sugg = if format_args.format_string_span.contains(value.span) {
-                        // Implicit argument. e.g. `format!("{x}")` span points to `{x}`
-                        let spdata = value.span.data();
-                        let span = Span::new(
-                            spdata.lo + BytePos(1),
-                            spdata.hi - BytePos(1),
-                            spdata.ctxt,
-                            spdata.parent
-                        );
-                        let snip = snippet_with_applicability(cx, span, "..", &mut applicability);
-                        if is_new_string {
-                            snip.into()
-                        } else {
-                            format!("{snip}.to_string()")
-                        }
-                    } else if is_new_string {
+                    let sugg = if is_new_string {
                         snippet_with_applicability(cx, value.span, "..", &mut applicability).into_owned()
                     } else {
                         let sugg = Sugg::hir_with_applicability(cx, value, "<arg>", &mut applicability);
diff --git a/tests/ui/format.fixed b/tests/ui/format.fixed
index d08f8f52495..f4db2d20c71 100644
--- a/tests/ui/format.fixed
+++ b/tests/ui/format.fixed
@@ -84,4 +84,10 @@ fn main() {
     let _ = x.to_string();
     let _ = format!("{x:?}"); // Don't lint on debug
     let _ = x.to_string();
+
+    // Issue #9234
+    let abc = "abc";
+    let _ = abc.to_string();
+    let xx = "xx";
+    let _ = xx.to_string();
 }
diff --git a/tests/ui/format.rs b/tests/ui/format.rs
index 4a10b580d26..bf687cb1e96 100644
--- a/tests/ui/format.rs
+++ b/tests/ui/format.rs
@@ -86,4 +86,10 @@ fn main() {
     let _ = format!("{x}");
     let _ = format!("{x:?}"); // Don't lint on debug
     let _ = format!("{y}", y = x);
+
+    // Issue #9234
+    let abc = "abc";
+    let _ = format!("{abc}");
+    let xx = "xx";
+    let _ = format!("{xx}");
 }
diff --git a/tests/ui/format.stderr b/tests/ui/format.stderr
index f25c7fb1ff1..a0f8e7d1937 100644
--- a/tests/ui/format.stderr
+++ b/tests/ui/format.stderr
@@ -111,5 +111,17 @@ error: useless use of `format!`
 LL |     let _ = format!("{y}", y = x);
    |             ^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `x.to_string()`
 
-error: aborting due to 17 previous errors
+error: useless use of `format!`
+  --> $DIR/format.rs:92:13
+   |
+LL |     let _ = format!("{abc}");
+   |             ^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `abc.to_string()`
+
+error: useless use of `format!`
+  --> $DIR/format.rs:94:13
+   |
+LL |     let _ = format!("{xx}");
+   |             ^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `xx.to_string()`
+
+error: aborting due to 19 previous errors