Fix #7903

5 files changed, 82 insertions, 23 deletions

diff --git a/clippy_utils/src/higher.rs b/clippy_utils/src/higher.rs
index 7cbd43e6266..17ee6e0b568 100644
--- a/clippy_utils/src/higher.rs
+++ b/clippy_utils/src/higher.rs
@@ -1,14 +1,14 @@
-//! This module contains functions that retrieves specifiec elements.
+//! This module contains functions that retrieve specific elements.
 
 #![deny(clippy::missing_docs_in_private_items)]
 
 use crate::ty::is_type_diagnostic_item;
-use crate::{is_expn_of, last_path_segment, match_def_path, paths};
+use crate::{is_expn_of, last_path_segment, match_def_path, path_to_local_id, paths};
 use if_chain::if_chain;
 use rustc_ast::ast::{self, LitKind};
 use rustc_hir as hir;
 use rustc_hir::{
-    Arm, Block, BorrowKind, Expr, ExprKind, HirId, LoopSource, MatchSource, Node, Pat, QPath, StmtKind, UnOp,
+    Arm, Block, BorrowKind, Expr, ExprKind, HirId, LoopSource, MatchSource, Node, Pat, PatKind, QPath, StmtKind, UnOp,
 };
 use rustc_lint::LateContext;
 use rustc_span::{sym, symbol, ExpnKind, Span, Symbol};
@@ -513,6 +513,8 @@ pub struct FormatArgsExpn<'tcx> {
     pub format_string_parts: &'tcx [Expr<'tcx>],
     /// Symbols corresponding to [`Self::format_string_parts`]
     pub format_string_symbols: Vec<Symbol>,
+    /// Match arm patterns, the `arg0`, etc. from the next field `args`
+    pub arg_names: &'tcx [Pat<'tcx>],
     /// Expressions like `ArgumentV1::new(arg0, Debug::fmt)`
     pub args: &'tcx [Expr<'tcx>],
     /// The final argument passed to `Arguments::new_v1_formatted`, if applicable
@@ -557,6 +559,7 @@ impl FormatArgsExpn<'tcx> {
                     _ => None,
                 })
                 .collect();
+            if let PatKind::Tuple(arg_names, None) = arm.pat.kind;
             if let ExprKind::Array(args) = arm.body.kind;
             then {
                 Some(FormatArgsExpn {
@@ -564,6 +567,7 @@ impl FormatArgsExpn<'tcx> {
                     value_args,
                     format_string_parts,
                     format_string_symbols,
+                    arg_names,
                     args,
                     fmt_expr,
                 })
@@ -587,9 +591,15 @@ impl FormatArgsExpn<'tcx> {
                             if let Some(position_field) = fields.iter().find(|f| f.ident.name == sym::position);
                             if let ExprKind::Lit(lit) = &position_field.expr.kind;
                             if let LitKind::Int(position, _) = lit.node;
+                            if let Ok(i) = usize::try_from(position);
+                            let arg = &self.args[i];
+                            if let ExprKind::Call(_, [arg_name, _]) = arg.kind;
+                            if let Some(j) = self
+                                .arg_names
+                                .iter()
+                                .position(|pat| path_to_local_id(arg_name, pat.hir_id));
                             then {
-                                let i = usize::try_from(position).unwrap();
-                                Some(FormatArgsArg { value: self.value_args[i], arg: &self.args[i], fmt: Some(fmt) })
+                                Some(FormatArgsArg { value: self.value_args[j], arg, fmt: Some(fmt) })
                             } else {
                                 None
                             }
diff --git a/tests/ui/format_args.fixed b/tests/ui/format_args.fixed
index 8376566c4d6..69b5e1c722e 100644
--- a/tests/ui/format_args.fixed
+++ b/tests/ui/format_args.fixed
@@ -5,6 +5,7 @@
 #![allow(unused_variables)]
 #![allow(clippy::assertions_on_constants)]
 #![allow(clippy::eq_op)]
+#![allow(clippy::print_literal)]
 #![warn(clippy::to_string_in_format_args)]
 
 use std::io::{stdout, Write};
@@ -97,9 +98,20 @@ fn main() {
     println!("{}", Z(1));
     println!("{}", **x);
     println!("{}", ***x_ref);
+    // https://github.com/rust-lang/rust-clippy/issues/7903
+    println!("{foo}{bar}", foo = "foo", bar = "bar");
+    println!("{foo}{bar}", foo = "foo", bar = "bar");
+    println!("{foo}{bar}", bar = "bar", foo = "foo");
+    println!("{foo}{bar}", bar = "bar", foo = "foo");
 
+    // negative tests
     println!("error: something failed at {}", Somewhere.to_string());
+    // The next two tests are negative because caching the string might be faster than calling `<X as
+    // Display>::fmt` twice.
     println!("{} and again {0}", x.to_string());
+    println!("{foo}{foo}", foo = "foo".to_string());
     my_macro!();
     println!("error: something failed at {}", my_other_macro!());
+    // https://github.com/rust-lang/rust-clippy/issues/7903
+    println!("{foo}{foo:?}", foo = "foo".to_string());
 }
diff --git a/tests/ui/format_args.rs b/tests/ui/format_args.rs
index 164cc07066d..3a434c5bf00 100644
--- a/tests/ui/format_args.rs
+++ b/tests/ui/format_args.rs
@@ -5,6 +5,7 @@
 #![allow(unused_variables)]
 #![allow(clippy::assertions_on_constants)]
 #![allow(clippy::eq_op)]
+#![allow(clippy::print_literal)]
 #![warn(clippy::to_string_in_format_args)]
 
 use std::io::{stdout, Write};
@@ -97,9 +98,20 @@ fn main() {
     println!("{}", Z(1).to_string());
     println!("{}", x.to_string());
     println!("{}", x_ref.to_string());
+    // https://github.com/rust-lang/rust-clippy/issues/7903
+    println!("{foo}{bar}", foo = "foo".to_string(), bar = "bar");
+    println!("{foo}{bar}", foo = "foo", bar = "bar".to_string());
+    println!("{foo}{bar}", bar = "bar".to_string(), foo = "foo");
+    println!("{foo}{bar}", bar = "bar", foo = "foo".to_string());
 
+    // negative tests
     println!("error: something failed at {}", Somewhere.to_string());
+    // The next two tests are negative because caching the string might be faster than calling `<X as
+    // Display>::fmt` twice.
     println!("{} and again {0}", x.to_string());
+    println!("{foo}{foo}", foo = "foo".to_string());
     my_macro!();
     println!("error: something failed at {}", my_other_macro!());
+    // https://github.com/rust-lang/rust-clippy/issues/7903
+    println!("{foo}{foo:?}", foo = "foo".to_string());
 }
diff --git a/tests/ui/format_args.stderr b/tests/ui/format_args.stderr
index 9cfc97edeaf..c0cbca50795 100644
--- a/tests/ui/format_args.stderr
+++ b/tests/ui/format_args.stderr
@@ -1,5 +1,5 @@
 error: `to_string` applied to a type that implements `Display` in `format!` args
-  --> $DIR/format_args.rs:75:72
+  --> $DIR/format_args.rs:76:72
    |
 LL |     let _ = format!("error: something failed at {}", Location::caller().to_string());
    |                                                                        ^^^^^^^^^^^^ help: remove this
@@ -7,100 +7,124 @@ LL |     let _ = format!("error: something failed at {}", Location::caller().to_
    = note: `-D clippy::to-string-in-format-args` implied by `-D warnings`
 
 error: `to_string` applied to a type that implements `Display` in `write!` args
-  --> $DIR/format_args.rs:79:27
+  --> $DIR/format_args.rs:80:27
    |
 LL |         Location::caller().to_string()
    |                           ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `writeln!` args
-  --> $DIR/format_args.rs:84:27
+  --> $DIR/format_args.rs:85:27
    |
 LL |         Location::caller().to_string()
    |                           ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `print!` args
-  --> $DIR/format_args.rs:86:63
+  --> $DIR/format_args.rs:87:63
    |
 LL |     print!("error: something failed at {}", Location::caller().to_string());
    |                                                               ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `println!` args
-  --> $DIR/format_args.rs:87:65
+  --> $DIR/format_args.rs:88:65
    |
 LL |     println!("error: something failed at {}", Location::caller().to_string());
    |                                                                 ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `eprint!` args
-  --> $DIR/format_args.rs:88:64
+  --> $DIR/format_args.rs:89:64
    |
 LL |     eprint!("error: something failed at {}", Location::caller().to_string());
    |                                                                ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `eprintln!` args
-  --> $DIR/format_args.rs:89:66
+  --> $DIR/format_args.rs:90:66
    |
 LL |     eprintln!("error: something failed at {}", Location::caller().to_string());
    |                                                                  ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `format_args!` args
-  --> $DIR/format_args.rs:90:77
+  --> $DIR/format_args.rs:91:77
    |
 LL |     let _ = format_args!("error: something failed at {}", Location::caller().to_string());
    |                                                                             ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `assert!` args
-  --> $DIR/format_args.rs:91:70
+  --> $DIR/format_args.rs:92:70
    |
 LL |     assert!(true, "error: something failed at {}", Location::caller().to_string());
    |                                                                      ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `assert_eq!` args
-  --> $DIR/format_args.rs:92:73
+  --> $DIR/format_args.rs:93:73
    |
 LL |     assert_eq!(0, 0, "error: something failed at {}", Location::caller().to_string());
    |                                                                         ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `assert_ne!` args
-  --> $DIR/format_args.rs:93:73
+  --> $DIR/format_args.rs:94:73
    |
 LL |     assert_ne!(0, 0, "error: something failed at {}", Location::caller().to_string());
    |                                                                         ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `panic!` args
-  --> $DIR/format_args.rs:94:63
+  --> $DIR/format_args.rs:95:63
    |
 LL |     panic!("error: something failed at {}", Location::caller().to_string());
    |                                                               ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `println!` args
-  --> $DIR/format_args.rs:95:20
+  --> $DIR/format_args.rs:96:20
    |
 LL |     println!("{}", X(1).to_string());
    |                    ^^^^^^^^^^^^^^^^ help: use this: `*X(1)`
 
 error: `to_string` applied to a type that implements `Display` in `println!` args
-  --> $DIR/format_args.rs:96:20
+  --> $DIR/format_args.rs:97:20
    |
 LL |     println!("{}", Y(&X(1)).to_string());
    |                    ^^^^^^^^^^^^^^^^^^^^ help: use this: `***Y(&X(1))`
 
 error: `to_string` applied to a type that implements `Display` in `println!` args
-  --> $DIR/format_args.rs:97:24
+  --> $DIR/format_args.rs:98:24
    |
 LL |     println!("{}", Z(1).to_string());
    |                        ^^^^^^^^^^^^ help: remove this
 
 error: `to_string` applied to a type that implements `Display` in `println!` args
-  --> $DIR/format_args.rs:98:20
+  --> $DIR/format_args.rs:99:20
    |
 LL |     println!("{}", x.to_string());
    |                    ^^^^^^^^^^^^^ help: use this: `**x`
 
 error: `to_string` applied to a type that implements `Display` in `println!` args
-  --> $DIR/format_args.rs:99:20
+  --> $DIR/format_args.rs:100:20
    |
 LL |     println!("{}", x_ref.to_string());
    |                    ^^^^^^^^^^^^^^^^^ help: use this: `***x_ref`
 
-error: aborting due to 17 previous errors
+error: `to_string` applied to a type that implements `Display` in `println!` args
+  --> $DIR/format_args.rs:102:39
+   |
+LL |     println!("{foo}{bar}", foo = "foo".to_string(), bar = "bar");
+   |                                       ^^^^^^^^^^^^ help: remove this
+
+error: `to_string` applied to a type that implements `Display` in `println!` args
+  --> $DIR/format_args.rs:103:52
+   |
+LL |     println!("{foo}{bar}", foo = "foo", bar = "bar".to_string());
+   |                                                    ^^^^^^^^^^^^ help: remove this
+
+error: `to_string` applied to a type that implements `Display` in `println!` args
+  --> $DIR/format_args.rs:104:39
+   |
+LL |     println!("{foo}{bar}", bar = "bar".to_string(), foo = "foo");
+   |                                       ^^^^^^^^^^^^ help: remove this
+
+error: `to_string` applied to a type that implements `Display` in `println!` args
+  --> $DIR/format_args.rs:105:52
+   |
+LL |     println!("{foo}{bar}", bar = "bar", foo = "foo".to_string());
+   |                                                    ^^^^^^^^^^^^ help: remove this
+
+error: aborting due to 21 previous errors
 
diff --git a/tests/ui/format_args_unfixable.rs b/tests/ui/format_args_unfixable.rs
index a8c06c2bde6..b24ddf7321e 100644
--- a/tests/ui/format_args_unfixable.rs
+++ b/tests/ui/format_args_unfixable.rs
@@ -51,6 +51,7 @@ fn main() {
     assert_ne!(0, 0, "error: {}", format!("something failed at {}", Location::caller()));
     panic!("error: {}", format!("something failed at {}", Location::caller()));
 
+    // negative tests
     println!("error: {}", format_args!("something failed at {}", Location::caller()));
     println!("error: {:>70}", format!("something failed at {}", Location::caller()));
     println!("error: {} {0}", format!("something failed at {}", Location::caller()));