Auto merge of rust-lang#7813 - xFrednet:6492-lint-version, r=flip1995

Add Clippy version to Clippy's lint list

Hey, hey, the semester is finally over, and I wanted to get back into hacking on Clippy. It has also been some time since our metadata collection monster has been feed. So, this PR adds a new attribute `clippy::version` to document which version a lint was stabilized. I considered using `git blame` but that would be very hacky and probably not accurate.

I'm also thinking that this attribute can be used to have a `clippy::nightly` lint group which is allow-by-default that delays setting the actual lint group until the defined version is reached. Just something to consider regarding rust-lang#6623 🙃

This PR only adds the version to 4 lints to keep it reviewable. I'll do a followup PR to add the version to other lints if the implementation is accepted 🙃

![image](https://user-images.githubusercontent.com/17087237/137118859-0aafdfdf-7595-4289-8ba4-33d58eb6991d.png)

Also, mobile approved xD

![image](https://user-images.githubusercontent.com/17087237/137118944-833cf7fb-a4a1-45d6-9af8-32c951822360.png)

---

r? `@flip1995`

cc: rust-lang#7172

closes: rust-lang#6492

changelog: [Clippy's lint list](https://rust-lang.github.io/rust-clippy/master/index.html) now displays the version a lint was added. 🎉

---

Example lint declaration after this update:

```rs
declare_clippy_lint! {
    /// [...]
    ///
    /// ### Example
    /// ```rust
    /// // Bad
    /// let x = 3.14;
    /// // Good
    /// let x = std::f32::consts::PI;
    /// ```
    #[clippy::version = "pre 1.29.0"]
    pub APPROX_CONSTANT,
    correctness,
    "the approximate of a known float constant (in `std::fXX::consts`)"
}
```

Author: bors

clippy_dev/Cargo.toml

@@ -12,6 +12,7 @@ opener = "0.5"
 regex = "1.5"
 shell-escape = "0.1"
 walkdir = "2.3"
+cargo_metadata = "0.14"
 
 [features]
 deny-warnings = []

clippy_dev/src/new_lint.rs

@@ -132,6 +132,18 @@ fn to_camel_case(name: &str) -> String {
         .collect()
 }
 
+fn get_stabilisation_version() -> String {
+    let mut command = cargo_metadata::MetadataCommand::new();
+    command.no_deps();
+    if let Ok(metadata) = command.exec() {
+        if let Some(pkg) = metadata.packages.iter().find(|pkg| pkg.name == "clippy") {
+            return format!("{}.{}.0", pkg.version.minor, pkg.version.patch);
+        }
+    }
+
+    String::from("<TODO set version(see doc/adding_lints.md)>")
+}
+
 fn get_test_file_contents(lint_name: &str, header_commands: Option<&str>) -> String {
     let mut contents = format!(
         indoc! {"
@@ -178,6 +190,7 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
         },
     };
 
+    let version = get_stabilisation_version();
     let lint_name = lint.name;
     let category = lint.category;
     let name_camel = to_camel_case(lint.name);
@@ -212,7 +225,7 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
     });
 
     result.push_str(&format!(
-        indoc! {"
+        indoc! {r#"
             declare_clippy_lint! {{
                 /// ### What it does
                 ///
@@ -226,11 +239,13 @@ fn get_lint_file_contents(lint: &LintData<'_>, enable_msrv: bool) -> String {
                 /// ```rust
                 /// // example code which does not raise clippy warning
                 /// ```
+                #[clippy::version = "{version}"]
                 pub {name_upper},
                 {category},
-                \"default lint description\"
+                "default lint description"
             }}
-        "},
+        "#},
+        version = version,
         name_upper = name_upper,
         category = category,
     ));

clippy_dev/src/update_lints.rs

@@ -18,6 +18,7 @@ static DEC_CLIPPY_LINT_RE: SyncLazy<Regex> = SyncLazy::new(|| {
         r#"(?x)
     declare_clippy_lint!\s*[\{(]
     (?:\s+///.*)*
+    (?:\s*\#\[clippy::version\s*=\s*"[^"]*"\])?
     \s+pub\s+(?P<name>[A-Z_][A-Z_0-9]*)\s*,\s*
     (?P<cat>[a-z_]+)\s*,\s*
     "(?P<desc>(?:[^"\\]+|\\(?s).(?-s))*)"\s*[})]
@@ -31,6 +32,7 @@ static DEC_DEPRECATED_LINT_RE: SyncLazy<Regex> = SyncLazy::new(|| {
         r#"(?x)
     declare_deprecated_lint!\s*[{(]\s*
     (?:\s+///.*)*
+    (?:\s*\#\[clippy::version\s*=\s*"[^"]*"\])?
     \s+pub\s+(?P<name>[A-Z_][A-Z_0-9]*)\s*,\s*
     "(?P<desc>(?:[^"\\]+|\\(?s).(?-s))*)"\s*[})]
 "#,
@@ -495,20 +497,23 @@ fn test_parse_contents() {
     let result: Vec<Lint> = parse_contents(
         r#"
 declare_clippy_lint! {
+    #[clippy::version = "Hello Clippy!"]
     pub PTR_ARG,
     style,
     "really long \
      text"
 }
 
 declare_clippy_lint!{
+    #[clippy::version = "Test version"]
     pub DOC_MARKDOWN,
     pedantic,
     "single line"
 }
 
 /// some doc comment
 declare_deprecated_lint! {
+    #[clippy::version = "I'm a version"]
     pub SHOULD_ASSERT_EQ,
     "`assert!()` will be more flexible with RFC 2011"
 }

clippy_lints/src/absurd_extreme_comparisons.rs

@@ -36,6 +36,7 @@ declare_clippy_lint! {
     /// if vec.len() <= 0 {}
     /// if 100 > i32::MAX {}
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub ABSURD_EXTREME_COMPARISONS,
     correctness,
     "a comparison with a maximum or minimum value that is always true or false"

clippy_lints/src/approx_const.rs

@@ -33,6 +33,7 @@ declare_clippy_lint! {
     /// let x = std::f32::consts::PI;
     /// let y = std::f64::consts::FRAC_1_PI;
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub APPROX_CONSTANT,
     correctness,
     "the approximate of a known float constant (in `std::fXX::consts`)"

clippy_lints/src/arithmetic.rs

@@ -25,6 +25,7 @@ declare_clippy_lint! {
     /// # let a = 0;
     /// a + 1;
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub INTEGER_ARITHMETIC,
     restriction,
     "any integer arithmetic expression which could overflow or panic"
@@ -43,6 +44,7 @@ declare_clippy_lint! {
     /// # let a = 0.0;
     /// a + 1.0;
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub FLOAT_ARITHMETIC,
     restriction,
     "any floating-point arithmetic statement"

clippy_lints/src/as_conversions.rs

@@ -38,6 +38,7 @@ declare_clippy_lint! {
     /// f(a.try_into().expect("Unexpected u16 overflow in f"));
     /// ```
     ///
+    #[clippy::version = "1.41.0"]
     pub AS_CONVERSIONS,
     restriction,
     "using a potentially dangerous silent `as` conversion"

clippy_lints/src/asm_syntax.rs

@@ -75,6 +75,7 @@ declare_clippy_lint! {
     /// asm!("lea ({}), {}", in(reg) ptr, lateout(reg) _, options(att_syntax));
     /// # }
     /// ```
+    #[clippy::version = "1.49.0"]
     pub INLINE_ASM_X86_INTEL_SYNTAX,
     restriction,
     "prefer AT&T x86 assembly syntax"
@@ -111,6 +112,7 @@ declare_clippy_lint! {
     /// asm!("lea {}, [{}]", lateout(reg) _, in(reg) ptr);
     /// # }
     /// ```
+    #[clippy::version = "1.49.0"]
     pub INLINE_ASM_X86_ATT_SYNTAX,
     restriction,
     "prefer Intel x86 assembly syntax"

clippy_lints/src/assertions_on_constants.rs

@@ -26,6 +26,7 @@ declare_clippy_lint! {
     /// const B: bool = false;
     /// assert!(B)
     /// ```
+    #[clippy::version = "1.34.0"]
     pub ASSERTIONS_ON_CONSTANTS,
     style,
     "`assert!(true)` / `assert!(false)` will be optimized out by the compiler, and should probably be replaced by a `panic!()` or `unreachable!()`"

clippy_lints/src/assign_ops.rs

@@ -34,6 +34,7 @@ declare_clippy_lint! {
     /// // Good
     /// a += b;
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub ASSIGN_OP_PATTERN,
     style,
     "assigning the result of an operation on a variable to that same variable"
@@ -60,6 +61,7 @@ declare_clippy_lint! {
     /// // ...
     /// a += a + b;
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub MISREFACTORED_ASSIGN_OP,
     suspicious,
     "having a variable on both sides of an assign op"