new uninlined_format_args lint to inline explicit arguments

Implement https://github.com/rust-lang/rust-clippy/issues/8368 - a new
lint to inline format arguments such as `print!("{}", var)` into
`print!("{var}")`.

code | suggestion | comment
---|---|---
`print!("{}", var)` | `print!("{var}")` |  simple variables
`print!("{0}", var)` | `print!("{var}")` |  positional variables
`print!("{v}", v=var)` | `print!("{var}")` |  named variables
`print!("{0} {0}", var)` | `print!("{var} {var}")` |  aliased variables
`print!("{0:1$}", var, width)` | `print!("{var:width$}")` |  width
support
`print!("{0:.1$}", var, prec)` | `print!("{var:.prec$}")` |  precision
support
`print!("{:.*}", prec, var)` | `print!("{var:.prec$}")` |  asterisk
support

code | suggestion | comment
---|---|---
`print!("{0}={1}", var, 1+2)` | `print!("{var}={0}", 1+2)` | Format
string uses an indexed argument that cannot be inlined.  Supporting this
case requires re-indexing of the format string.

changelog: [`uninlined_format_args`]: A new lint to inline format
arguments, i.e. `print!("{}", var)` into `print!("{var}")`

3 files changed, 1205 insertions, 0 deletions

diff --git a/tests/ui/uninlined_format_args.fixed b/tests/ui/uninlined_format_args.fixed
new file mode 100644
index 00000000000..bade0ed8ad6
--- /dev/null
+++ b/tests/ui/uninlined_format_args.fixed
@@ -0,0 +1,168 @@
+// run-rustfix
+
+#![allow(clippy::eq_op)]
+#![allow(clippy::format_in_format_args)]
+#![allow(clippy::print_literal)]
+#![allow(named_arguments_used_positionally)]
+#![allow(unused_variables, unused_imports, unused_macros)]
+#![warn(clippy::uninlined_format_args)]
+#![feature(custom_inner_attributes)]
+
+macro_rules! no_param_str {
+    () => {
+        "{}"
+    };
+}
+
+macro_rules! pass_through {
+    ($expr:expr) => {
+        $expr
+    };
+}
+
+macro_rules! my_println {
+   ($($args:tt),*) => {{
+        println!($($args),*)
+    }};
+}
+
+macro_rules! my_println_args {
+    ($($args:tt),*) => {{
+        println!("foo: {}", format_args!($($args),*))
+    }};
+}
+
+fn tester(fn_arg: i32) {
+    let local_i32 = 1;
+    let local_f64 = 2.0;
+    let local_opt: Option<i32> = Some(3);
+    let width = 4;
+    let prec = 5;
+    let val = 6;
+
+    // make sure this file hasn't been corrupted with tabs converted to spaces
+    // let _ = '	';  // <- this is a single tab character
+    let _: &[u8; 3] = b"	 	"; // <- <tab><space><tab>
+
+    println!("val='{local_i32}'");
+    println!("val='{local_i32}'"); // 3 spaces
+    println!("val='{local_i32}'"); // tab
+    println!("val='{local_i32}'"); // space+tab
+    println!("val='{local_i32}'"); // tab+space
+    println!(
+        "val='{local_i32}'"
+    );
+    println!("{local_i32}");
+    println!("{fn_arg}");
+    println!("{local_i32:?}");
+    println!("{local_i32:#?}");
+    println!("{local_i32:4}");
+    println!("{local_i32:04}");
+    println!("{local_i32:<3}");
+    println!("{local_i32:#010x}");
+    println!("{local_f64:.1}");
+    println!("Hello {} is {local_f64:.local_i32$}", "x");
+    println!("Hello {local_i32} is {local_f64:.*}", 5);
+    println!("Hello {local_i32} is {local_f64:.*}", 5);
+    println!("{local_i32} {local_f64}");
+    println!("{local_i32}, {}", local_opt.unwrap());
+    println!("{val}");
+    println!("{val}");
+    println!("{} {1}", local_i32, 42);
+    println!("val='{local_i32}'");
+    println!("val='{local_i32}'");
+    println!("val='{local_i32}'");
+    println!("val='{fn_arg}'");
+    println!("{local_i32}");
+    println!("{local_i32:?}");
+    println!("{local_i32:#?}");
+    println!("{local_i32:04}");
+    println!("{local_i32:<3}");
+    println!("{local_i32:#010x}");
+    println!("{local_f64:.1}");
+    println!("{local_i32} {local_i32}");
+    println!("{local_f64} {local_i32} {local_i32} {local_f64}");
+    println!("{local_i32} {local_f64}");
+    println!("{local_f64} {local_i32}");
+    println!("{local_f64} {local_i32} {local_f64} {local_i32}");
+    println!("{1} {0}", "str", local_i32);
+    println!("{local_i32}");
+    println!("{local_i32:width$}");
+    println!("{local_i32:width$}");
+    println!("{local_i32:.prec$}");
+    println!("{local_i32:.prec$}");
+    println!("{val:val$}");
+    println!("{val:val$}");
+    println!("{val:val$.val$}");
+    println!("{val:val$.val$}");
+    println!("{val:val$.val$}");
+    println!("{val:val$.val$}");
+    println!("{val:val$.val$}");
+    println!("{val:val$.val$}");
+    println!("{val:val$.val$}");
+    println!("{val:val$.val$}");
+    println!("{width:width$}");
+    println!("{local_i32:width$}");
+    println!("{width:width$}");
+    println!("{local_i32:width$}");
+    println!("{prec:.prec$}");
+    println!("{local_i32:.prec$}");
+    println!("{prec:.prec$}");
+    println!("{local_i32:.prec$}");
+    println!("{width:width$.prec$}");
+    println!("{width:width$.prec$}");
+    println!("{local_f64:width$.prec$}");
+    println!("{local_f64:width$.prec$} {local_f64} {width} {prec}");
+    println!(
+        "{local_i32:width$.prec$} {local_i32:prec$.width$} {width:local_i32$.prec$} {width:prec$.local_i32$} {prec:local_i32$.width$} {prec:width$.local_i32$}",
+    );
+    println!(
+        "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$} {3}",
+        local_i32,
+        width,
+        prec,
+        1 + 2
+    );
+    println!("Width = {local_i32}, value with width = {local_f64:local_i32$}");
+    println!("{local_i32:width$.prec$}");
+    println!("{width:width$.prec$}");
+    println!("{}", format!("{local_i32}"));
+    my_println!("{}", local_i32);
+    my_println_args!("{}", local_i32);
+
+    // these should NOT be modified by the lint
+    println!(concat!("nope ", "{}"), local_i32);
+    println!("val='{local_i32}'");
+    println!("val='{local_i32 }'");
+    println!("val='{local_i32	}'"); // with tab
+    println!("val='{local_i32\n}'");
+    println!("{}", usize::MAX);
+    println!("{}", local_opt.unwrap());
+    println!(
+        "val='{local_i32
+    }'"
+    );
+    println!(no_param_str!(), local_i32);
+
+    // FIXME: bugs!
+    // println!(pass_through!("foo={local_i32}"), local_i32 = local_i32);
+    // println!(pass_through!("foo={}"), local_i32);
+    // println!(indoc!("foo={}"), local_i32);
+    // printdoc!("foo={}", local_i32);
+}
+
+fn main() {
+    tester(42);
+}
+
+fn _under_msrv() {
+    #![clippy::msrv = "1.57"]
+    let local_i32 = 1;
+    println!("don't expand='{}'", local_i32);
+}
+
+fn _meets_msrv() {
+    #![clippy::msrv = "1.58"]
+    let local_i32 = 1;
+    println!("expand='{local_i32}'");
+}
diff --git a/tests/ui/uninlined_format_args.rs b/tests/ui/uninlined_format_args.rs
new file mode 100644
index 00000000000..ac958f9e5b6
--- /dev/null
+++ b/tests/ui/uninlined_format_args.rs
@@ -0,0 +1,171 @@
+// run-rustfix
+
+#![allow(clippy::eq_op)]
+#![allow(clippy::format_in_format_args)]
+#![allow(clippy::print_literal)]
+#![allow(named_arguments_used_positionally)]
+#![allow(unused_variables, unused_imports, unused_macros)]
+#![warn(clippy::uninlined_format_args)]
+#![feature(custom_inner_attributes)]
+
+macro_rules! no_param_str {
+    () => {
+        "{}"
+    };
+}
+
+macro_rules! pass_through {
+    ($expr:expr) => {
+        $expr
+    };
+}
+
+macro_rules! my_println {
+   ($($args:tt),*) => {{
+        println!($($args),*)
+    }};
+}
+
+macro_rules! my_println_args {
+    ($($args:tt),*) => {{
+        println!("foo: {}", format_args!($($args),*))
+    }};
+}
+
+fn tester(fn_arg: i32) {
+    let local_i32 = 1;
+    let local_f64 = 2.0;
+    let local_opt: Option<i32> = Some(3);
+    let width = 4;
+    let prec = 5;
+    let val = 6;
+
+    // make sure this file hasn't been corrupted with tabs converted to spaces
+    // let _ = '	';  // <- this is a single tab character
+    let _: &[u8; 3] = b"	 	"; // <- <tab><space><tab>
+
+    println!("val='{}'", local_i32);
+    println!("val='{   }'", local_i32); // 3 spaces
+    println!("val='{	}'", local_i32); // tab
+    println!("val='{ 	}'", local_i32); // space+tab
+    println!("val='{	 }'", local_i32); // tab+space
+    println!(
+        "val='{
+    }'",
+        local_i32
+    );
+    println!("{}", local_i32);
+    println!("{}", fn_arg);
+    println!("{:?}", local_i32);
+    println!("{:#?}", local_i32);
+    println!("{:4}", local_i32);
+    println!("{:04}", local_i32);
+    println!("{:<3}", local_i32);
+    println!("{:#010x}", local_i32);
+    println!("{:.1}", local_f64);
+    println!("Hello {} is {:.*}", "x", local_i32, local_f64);
+    println!("Hello {} is {:.*}", local_i32, 5, local_f64);
+    println!("Hello {} is {2:.*}", local_i32, 5, local_f64);
+    println!("{} {}", local_i32, local_f64);
+    println!("{}, {}", local_i32, local_opt.unwrap());
+    println!("{}", val);
+    println!("{}", v = val);
+    println!("{} {1}", local_i32, 42);
+    println!("val='{\t }'", local_i32);
+    println!("val='{\n }'", local_i32);
+    println!("val='{local_i32}'", local_i32 = local_i32);
+    println!("val='{local_i32}'", local_i32 = fn_arg);
+    println!("{0}", local_i32);
+    println!("{0:?}", local_i32);
+    println!("{0:#?}", local_i32);
+    println!("{0:04}", local_i32);
+    println!("{0:<3}", local_i32);
+    println!("{0:#010x}", local_i32);
+    println!("{0:.1}", local_f64);
+    println!("{0} {0}", local_i32);
+    println!("{1} {} {0} {}", local_i32, local_f64);
+    println!("{0} {1}", local_i32, local_f64);
+    println!("{1} {0}", local_i32, local_f64);
+    println!("{1} {0} {1} {0}", local_i32, local_f64);
+    println!("{1} {0}", "str", local_i32);
+    println!("{v}", v = local_i32);
+    println!("{local_i32:0$}", width);
+    println!("{local_i32:w$}", w = width);
+    println!("{local_i32:.0$}", prec);
+    println!("{local_i32:.p$}", p = prec);
+    println!("{:0$}", v = val);
+    println!("{0:0$}", v = val);
+    println!("{:0$.0$}", v = val);
+    println!("{0:0$.0$}", v = val);
+    println!("{0:0$.v$}", v = val);
+    println!("{0:v$.0$}", v = val);
+    println!("{v:0$.0$}", v = val);
+    println!("{v:v$.0$}", v = val);
+    println!("{v:0$.v$}", v = val);
+    println!("{v:v$.v$}", v = val);
+    println!("{:0$}", width);
+    println!("{:1$}", local_i32, width);
+    println!("{:w$}", w = width);
+    println!("{:w$}", local_i32, w = width);
+    println!("{:.0$}", prec);
+    println!("{:.1$}", local_i32, prec);
+    println!("{:.p$}", p = prec);
+    println!("{:.p$}", local_i32, p = prec);
+    println!("{:0$.1$}", width, prec);
+    println!("{:0$.w$}", width, w = prec);
+    println!("{:1$.2$}", local_f64, width, prec);
+    println!("{:1$.2$} {0} {1} {2}", local_f64, width, prec);
+    println!(
+        "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$}",
+        local_i32, width, prec,
+    );
+    println!(
+        "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$} {3}",
+        local_i32,
+        width,
+        prec,
+        1 + 2
+    );
+    println!("Width = {}, value with width = {:0$}", local_i32, local_f64);
+    println!("{:w$.p$}", local_i32, w = width, p = prec);
+    println!("{:w$.p$}", w = width, p = prec);
+    println!("{}", format!("{}", local_i32));
+    my_println!("{}", local_i32);
+    my_println_args!("{}", local_i32);
+
+    // these should NOT be modified by the lint
+    println!(concat!("nope ", "{}"), local_i32);
+    println!("val='{local_i32}'");
+    println!("val='{local_i32 }'");
+    println!("val='{local_i32	}'"); // with tab
+    println!("val='{local_i32\n}'");
+    println!("{}", usize::MAX);
+    println!("{}", local_opt.unwrap());
+    println!(
+        "val='{local_i32
+    }'"
+    );
+    println!(no_param_str!(), local_i32);
+
+    // FIXME: bugs!
+    // println!(pass_through!("foo={local_i32}"), local_i32 = local_i32);
+    // println!(pass_through!("foo={}"), local_i32);
+    // println!(indoc!("foo={}"), local_i32);
+    // printdoc!("foo={}", local_i32);
+}
+
+fn main() {
+    tester(42);
+}
+
+fn _under_msrv() {
+    #![clippy::msrv = "1.57"]
+    let local_i32 = 1;
+    println!("don't expand='{}'", local_i32);
+}
+
+fn _meets_msrv() {
+    #![clippy::msrv = "1.58"]
+    let local_i32 = 1;
+    println!("expand='{}'", local_i32);
+}
diff --git a/tests/ui/uninlined_format_args.stderr b/tests/ui/uninlined_format_args.stderr
new file mode 100644
index 00000000000..7e652d0354f
--- /dev/null
+++ b/tests/ui/uninlined_format_args.stderr
@@ -0,0 +1,866 @@
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:47:5
+   |
+LL |     println!("val='{}'", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::uninlined-format-args` implied by `-D warnings`
+help: change this to
+   |
+LL -     println!("val='{}'", local_i32);
+LL +     println!("val='{local_i32}'");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:48:5
+   |
+LL |     println!("val='{   }'", local_i32); // 3 spaces
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("val='{   }'", local_i32); // 3 spaces
+LL +     println!("val='{local_i32}'"); // 3 spaces
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:49:5
+   |
+LL |     println!("val='{    }'", local_i32); // tab
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("val='{    }'", local_i32); // tab
+LL +     println!("val='{local_i32}'"); // tab
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:50:5
+   |
+LL |     println!("val='{     }'", local_i32); // space+tab
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("val='{     }'", local_i32); // space+tab
+LL +     println!("val='{local_i32}'"); // space+tab
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:51:5
+   |
+LL |     println!("val='{     }'", local_i32); // tab+space
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("val='{     }'", local_i32); // tab+space
+LL +     println!("val='{local_i32}'"); // tab+space
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:52:5
+   |
+LL | /     println!(
+LL | |         "val='{
+LL | |     }'",
+LL | |         local_i32
+LL | |     );
+   | |_____^
+   |
+help: change this to
+   |
+LL -         "val='{
+LL +         "val='{local_i32}'"
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:57:5
+   |
+LL |     println!("{}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{}", local_i32);
+LL +     println!("{local_i32}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:58:5
+   |
+LL |     println!("{}", fn_arg);
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{}", fn_arg);
+LL +     println!("{fn_arg}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:59:5
+   |
+LL |     println!("{:?}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:?}", local_i32);
+LL +     println!("{local_i32:?}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:60:5
+   |
+LL |     println!("{:#?}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:#?}", local_i32);
+LL +     println!("{local_i32:#?}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:61:5
+   |
+LL |     println!("{:4}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:4}", local_i32);
+LL +     println!("{local_i32:4}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:62:5
+   |
+LL |     println!("{:04}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:04}", local_i32);
+LL +     println!("{local_i32:04}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:63:5
+   |
+LL |     println!("{:<3}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:<3}", local_i32);
+LL +     println!("{local_i32:<3}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:64:5
+   |
+LL |     println!("{:#010x}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:#010x}", local_i32);
+LL +     println!("{local_i32:#010x}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:65:5
+   |
+LL |     println!("{:.1}", local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:.1}", local_f64);
+LL +     println!("{local_f64:.1}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:66:5
+   |
+LL |     println!("Hello {} is {:.*}", "x", local_i32, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("Hello {} is {:.*}", "x", local_i32, local_f64);
+LL +     println!("Hello {} is {local_f64:.local_i32$}", "x");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:67:5
+   |
+LL |     println!("Hello {} is {:.*}", local_i32, 5, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("Hello {} is {:.*}", local_i32, 5, local_f64);
+LL +     println!("Hello {local_i32} is {local_f64:.*}", 5);
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:68:5
+   |
+LL |     println!("Hello {} is {2:.*}", local_i32, 5, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("Hello {} is {2:.*}", local_i32, 5, local_f64);
+LL +     println!("Hello {local_i32} is {local_f64:.*}", 5);
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:69:5
+   |
+LL |     println!("{} {}", local_i32, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{} {}", local_i32, local_f64);
+LL +     println!("{local_i32} {local_f64}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:70:5
+   |
+LL |     println!("{}, {}", local_i32, local_opt.unwrap());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{}, {}", local_i32, local_opt.unwrap());
+LL +     println!("{local_i32}, {}", local_opt.unwrap());
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:71:5
+   |
+LL |     println!("{}", val);
+   |     ^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{}", val);
+LL +     println!("{val}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:72:5
+   |
+LL |     println!("{}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{}", v = val);
+LL +     println!("{val}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:74:5
+   |
+LL |     println!("val='{/t }'", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("val='{/t }'", local_i32);
+LL +     println!("val='{local_i32}'");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:75:5
+   |
+LL |     println!("val='{/n }'", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("val='{/n }'", local_i32);
+LL +     println!("val='{local_i32}'");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:76:5
+   |
+LL |     println!("val='{local_i32}'", local_i32 = local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("val='{local_i32}'", local_i32 = local_i32);
+LL +     println!("val='{local_i32}'");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:77:5
+   |
+LL |     println!("val='{local_i32}'", local_i32 = fn_arg);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("val='{local_i32}'", local_i32 = fn_arg);
+LL +     println!("val='{fn_arg}'");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:78:5
+   |
+LL |     println!("{0}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0}", local_i32);
+LL +     println!("{local_i32}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:79:5
+   |
+LL |     println!("{0:?}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:?}", local_i32);
+LL +     println!("{local_i32:?}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:80:5
+   |
+LL |     println!("{0:#?}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:#?}", local_i32);
+LL +     println!("{local_i32:#?}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:81:5
+   |
+LL |     println!("{0:04}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:04}", local_i32);
+LL +     println!("{local_i32:04}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:82:5
+   |
+LL |     println!("{0:<3}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:<3}", local_i32);
+LL +     println!("{local_i32:<3}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:83:5
+   |
+LL |     println!("{0:#010x}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:#010x}", local_i32);
+LL +     println!("{local_i32:#010x}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:84:5
+   |
+LL |     println!("{0:.1}", local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:.1}", local_f64);
+LL +     println!("{local_f64:.1}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:85:5
+   |
+LL |     println!("{0} {0}", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0} {0}", local_i32);
+LL +     println!("{local_i32} {local_i32}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:86:5
+   |
+LL |     println!("{1} {} {0} {}", local_i32, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{1} {} {0} {}", local_i32, local_f64);
+LL +     println!("{local_f64} {local_i32} {local_i32} {local_f64}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:87:5
+   |
+LL |     println!("{0} {1}", local_i32, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0} {1}", local_i32, local_f64);
+LL +     println!("{local_i32} {local_f64}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:88:5
+   |
+LL |     println!("{1} {0}", local_i32, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{1} {0}", local_i32, local_f64);
+LL +     println!("{local_f64} {local_i32}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:89:5
+   |
+LL |     println!("{1} {0} {1} {0}", local_i32, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{1} {0} {1} {0}", local_i32, local_f64);
+LL +     println!("{local_f64} {local_i32} {local_f64} {local_i32}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:91:5
+   |
+LL |     println!("{v}", v = local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{v}", v = local_i32);
+LL +     println!("{local_i32}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:92:5
+   |
+LL |     println!("{local_i32:0$}", width);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{local_i32:0$}", width);
+LL +     println!("{local_i32:width$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:93:5
+   |
+LL |     println!("{local_i32:w$}", w = width);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{local_i32:w$}", w = width);
+LL +     println!("{local_i32:width$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:94:5
+   |
+LL |     println!("{local_i32:.0$}", prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{local_i32:.0$}", prec);
+LL +     println!("{local_i32:.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:95:5
+   |
+LL |     println!("{local_i32:.p$}", p = prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{local_i32:.p$}", p = prec);
+LL +     println!("{local_i32:.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:96:5
+   |
+LL |     println!("{:0$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:0$}", v = val);
+LL +     println!("{val:val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:97:5
+   |
+LL |     println!("{0:0$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:0$}", v = val);
+LL +     println!("{val:val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:98:5
+   |
+LL |     println!("{:0$.0$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:0$.0$}", v = val);
+LL +     println!("{val:val$.val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:99:5
+   |
+LL |     println!("{0:0$.0$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:0$.0$}", v = val);
+LL +     println!("{val:val$.val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:100:5
+   |
+LL |     println!("{0:0$.v$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:0$.v$}", v = val);
+LL +     println!("{val:val$.val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:101:5
+   |
+LL |     println!("{0:v$.0$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{0:v$.0$}", v = val);
+LL +     println!("{val:val$.val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:102:5
+   |
+LL |     println!("{v:0$.0$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{v:0$.0$}", v = val);
+LL +     println!("{val:val$.val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:103:5
+   |
+LL |     println!("{v:v$.0$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{v:v$.0$}", v = val);
+LL +     println!("{val:val$.val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:104:5
+   |
+LL |     println!("{v:0$.v$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{v:0$.v$}", v = val);
+LL +     println!("{val:val$.val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:105:5
+   |
+LL |     println!("{v:v$.v$}", v = val);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{v:v$.v$}", v = val);
+LL +     println!("{val:val$.val$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:106:5
+   |
+LL |     println!("{:0$}", width);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:0$}", width);
+LL +     println!("{width:width$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:107:5
+   |
+LL |     println!("{:1$}", local_i32, width);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:1$}", local_i32, width);
+LL +     println!("{local_i32:width$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:108:5
+   |
+LL |     println!("{:w$}", w = width);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:w$}", w = width);
+LL +     println!("{width:width$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:109:5
+   |
+LL |     println!("{:w$}", local_i32, w = width);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:w$}", local_i32, w = width);
+LL +     println!("{local_i32:width$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:110:5
+   |
+LL |     println!("{:.0$}", prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:.0$}", prec);
+LL +     println!("{prec:.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:111:5
+   |
+LL |     println!("{:.1$}", local_i32, prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:.1$}", local_i32, prec);
+LL +     println!("{local_i32:.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:112:5
+   |
+LL |     println!("{:.p$}", p = prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:.p$}", p = prec);
+LL +     println!("{prec:.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:113:5
+   |
+LL |     println!("{:.p$}", local_i32, p = prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:.p$}", local_i32, p = prec);
+LL +     println!("{local_i32:.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:114:5
+   |
+LL |     println!("{:0$.1$}", width, prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:0$.1$}", width, prec);
+LL +     println!("{width:width$.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:115:5
+   |
+LL |     println!("{:0$.w$}", width, w = prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:0$.w$}", width, w = prec);
+LL +     println!("{width:width$.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:116:5
+   |
+LL |     println!("{:1$.2$}", local_f64, width, prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:1$.2$}", local_f64, width, prec);
+LL +     println!("{local_f64:width$.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:117:5
+   |
+LL |     println!("{:1$.2$} {0} {1} {2}", local_f64, width, prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:1$.2$} {0} {1} {2}", local_f64, width, prec);
+LL +     println!("{local_f64:width$.prec$} {local_f64} {width} {prec}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:118:5
+   |
+LL | /     println!(
+LL | |         "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$}",
+LL | |         local_i32, width, prec,
+LL | |     );
+   | |_____^
+   |
+help: change this to
+   |
+LL ~         "{local_i32:width$.prec$} {local_i32:prec$.width$} {width:local_i32$.prec$} {width:prec$.local_i32$} {prec:local_i32$.width$} {prec:width$.local_i32$}", width, prec,
+LL ~         "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$}", width, prec,
+LL ~         "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$}", width, prec,
+LL ~         "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$}", width, prec,
+LL ~         "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$}", width, prec,
+LL ~         "{0:1$.2$} {0:2$.1$} {1:0$.2$} {1:2$.0$} {2:0$.1$} {2:1$.0$}",
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:129:5
+   |
+LL |     println!("Width = {}, value with width = {:0$}", local_i32, local_f64);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("Width = {}, value with width = {:0$}", local_i32, local_f64);
+LL +     println!("Width = {local_i32}, value with width = {local_f64:local_i32$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:130:5
+   |
+LL |     println!("{:w$.p$}", local_i32, w = width, p = prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:w$.p$}", local_i32, w = width, p = prec);
+LL +     println!("{local_i32:width$.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:131:5
+   |
+LL |     println!("{:w$.p$}", w = width, p = prec);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{:w$.p$}", w = width, p = prec);
+LL +     println!("{width:width$.prec$}");
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:132:20
+   |
+LL |     println!("{}", format!("{}", local_i32));
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("{}", format!("{}", local_i32));
+LL +     println!("{}", format!("{local_i32}"));
+   |
+
+error: variables can be used directly in the `format!` string
+  --> $DIR/uninlined_format_args.rs:170:5
+   |
+LL |     println!("expand='{}'", local_i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: change this to
+   |
+LL -     println!("expand='{}'", local_i32);
+LL +     println!("expand='{local_i32}'");
+   |
+
+error: aborting due to 71 previous errors
+