unnecessary_debug_formatting respect MSRV

`unnecessary_debug_formatting` suggested display() regardless of
MSRV. This adds MSRV check for OsStr and  Path.

changelog: [`unnecessary_debug_formatting`]: respects MSRV

Author: donkomura

book/src/lint_configuration.md

@@ -866,6 +866,7 @@ The minimum rust version that the project supports. Defaults to the `rust-versio
 * [`type_repetition_in_bounds`](https://rust-lang.github.io/rust-clippy/master/index.html#type_repetition_in_bounds)
 * [`unchecked_duration_subtraction`](https://rust-lang.github.io/rust-clippy/master/index.html#unchecked_duration_subtraction)
 * [`uninlined_format_args`](https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args)
+* [`unnecessary_debug_formatting`](https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_debug_formatting)
 * [`unnecessary_lazy_evaluations`](https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations)
 * [`unnested_or_patterns`](https://rust-lang.github.io/rust-clippy/master/index.html#unnested_or_patterns)
 * [`unused_trait_names`](https://rust-lang.github.io/rust-clippy/master/index.html#unused_trait_names)

clippy_config/src/conf.rs

@@ -769,6 +769,7 @@ define_Conf! {
         type_repetition_in_bounds,
         unchecked_duration_subtraction,
         uninlined_format_args,
+        unnecessary_debug_formatting,
         unnecessary_lazy_evaluations,
         unnested_or_patterns,
         unused_trait_names,

clippy_lints/src/format_args.rs

@@ -541,6 +541,7 @@ impl<'tcx> FormatArgsExpr<'_, 'tcx> {
             && !is_from_proc_macro(cx, value)
             && let ty = cx.typeck_results().expr_ty(value)
             && self.can_display_format(ty)
+            && self.msrv.meets(cx, msrvs::UNNECESSARY_DEBUG_FORMATTING)
         {
             // If the parent function is a method of `Debug`, we don't want to lint
             // because it is likely that the user wants to use `Debug` formatting.

clippy_utils/src/msrvs.rs

@@ -24,7 +24,7 @@ macro_rules! msrv_aliases {
 // names may refer to stabilized feature flags or library items
 msrv_aliases! {
     1,88,0 { LET_CHAINS }
-    1,87,0 { OS_STR_DISPLAY, INT_MIDPOINT, CONST_CHAR_IS_DIGIT }
+    1,87,0 { OS_STR_DISPLAY, INT_MIDPOINT, CONST_CHAR_IS_DIGIT, UNNECESSARY_DEBUG_FORMATTING }
     1,85,0 { UINT_FLOAT_MIDPOINT, CONST_SIZE_OF_VAL }
     1,84,0 { CONST_OPTION_AS_SLICE, MANUAL_DANGLING_PTR }
     1,83,0 { CONST_EXTERN_FN, CONST_FLOAT_BITS_CONV, CONST_FLOAT_CLASSIFY, CONST_MUT_REFS, CONST_UNWRAP }

tests/ui/unnecessary_os_str_debug_formatting.rs

@@ -21,3 +21,20 @@ fn main() {
     let _: String = format!("{:?}", os_str); //~ unnecessary_debug_formatting
     let _: String = format!("{:?}", os_string); //~ unnecessary_debug_formatting
 }
+
+#[clippy::msrv = "1.86"]
+fn msrv_1_86() {
+    let os_str = OsStr::new("test");
+
+    // Should not lint because MSRV is 1.86, but display() was stabilized in 1.87
+    println!("{:?}", os_str);
+}
+
+#[clippy::msrv = "1.87"]
+fn msrv_1_87() {
+    let os_str = OsStr::new("test");
+
+    // Should lint because MSRV is 1.87 and display() is available
+    println!("{:?}", os_str);
+    //~^ unnecessary_debug_formatting
+}

tests/ui/unnecessary_os_str_debug_formatting.stderr

@@ -54,5 +54,14 @@ LL |     let _: String = format!("{:?}", os_string);
    = help: use `Display` formatting and change this to `os_string.display()`
    = note: switching to `Display` formatting will change how the value is shown; escaped characters will no longer be escaped and surrounding quotes will be removed
 
-error: aborting due to 6 previous errors
+error: unnecessary `Debug` formatting in `println!` args
+  --> tests/ui/unnecessary_os_str_debug_formatting.rs:38:22
+   |
+LL |     println!("{:?}", os_str);
+   |                      ^^^^^^
+   |
+   = help: use `Display` formatting and change this to `os_str.display()`
+   = note: switching to `Display` formatting will change how the value is shown; escaped characters will no longer be escaped and surrounding quotes will be removed
+
+error: aborting due to 7 previous errors
 

tests/ui/unnecessary_path_debug_formatting.rs

@@ -48,3 +48,25 @@ fn issue_14345() {
     let input = std::path::Path::new("/foo/bar");
     assert!(input.ends_with("baz"), "{input:?}");
 }
+
+#[clippy::msrv = "1.86"]
+fn msrv_1_86() {
+    let path = Path::new("/test");
+    let path_buf = PathBuf::from("/test");
+
+    // Should not lint because MSRV is 1.86, but display() was stabilized in 1.87
+    println!("{:?}", path);
+    println!("{:?}", path_buf);
+}
+
+#[clippy::msrv = "1.87"]
+fn msrv_1_87() {
+    let path = Path::new("/test");
+    let path_buf = PathBuf::from("/test");
+
+    // Should lint because MSRV is 1.87 and display() is available
+    println!("{:?}", path);
+    //~^ unnecessary_debug_formatting
+    println!("{:?}", path_buf);
+    //~^ unnecessary_debug_formatting
+}

tests/ui/unnecessary_path_debug_formatting.stderr

@@ -81,5 +81,23 @@ LL |     println!("{:?}", &*deref_path);
    = help: use `Display` formatting and change this to `&*deref_path.display()`
    = note: switching to `Display` formatting will change how the value is shown; escaped characters will no longer be escaped and surrounding quotes will be removed
 
-error: aborting due to 9 previous errors
+error: unnecessary `Debug` formatting in `println!` args
+  --> tests/ui/unnecessary_path_debug_formatting.rs:68:22
+   |
+LL |     println!("{:?}", path);
+   |                      ^^^^
+   |
+   = help: use `Display` formatting and change this to `path.display()`
+   = note: switching to `Display` formatting will change how the value is shown; escaped characters will no longer be escaped and surrounding quotes will be removed
+
+error: unnecessary `Debug` formatting in `println!` args
+  --> tests/ui/unnecessary_path_debug_formatting.rs:70:22
+   |
+LL |     println!("{:?}", path_buf);
+   |                      ^^^^^^^^
+   |
+   = help: use `Display` formatting and change this to `path_buf.display()`
+   = note: switching to `Display` formatting will change how the value is shown; escaped characters will no longer be escaped and surrounding quotes will be removed
+
+error: aborting due to 11 previous errors