Auto merge of rust-lang#10889 - blyxyas:link-config-desc, r=flip1995

Add configuration values auto markdown links to `CHANGELOG.md`

Related to [this Zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/257328-clippy/topic/Revisiting.20.20Clippy's.20configuration.20discover/near/363119950).

Now `cargo dev update_lints` also includes configurations as Markdown links, so changes to configuration can be linked directly.
It links to [this file](https://github.com/rust-lang/rust-clippy/blob/master/book/src/lint_configuration.md) (`book/src/lint_configuration.md`) because a new changelog may be deployed before the website is updated. So, in order to avoid broken links, this is the simplest way.

changelog:none

CHANGELOG.md

@@ -5322,3 +5322,62 @@ Released 2018-09-13
 [`zero_width_space`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_width_space
 [`zst_offset`]: https://rust-lang.github.io/rust-clippy/master/index.html#zst_offset
 <!-- end autogenerated links to lint list -->
+<!-- begin autogenerated links to configuration documentation -->
+[`arithmetic-side-effects-allowed`]: https://doc.rust-lang.org/clippy/lint_configuration.html#arithmetic-side-effects-allowed
+[`arithmetic-side-effects-allowed-binary`]: https://doc.rust-lang.org/clippy/lint_configuration.html#arithmetic-side-effects-allowed-binary
+[`arithmetic-side-effects-allowed-unary`]: https://doc.rust-lang.org/clippy/lint_configuration.html#arithmetic-side-effects-allowed-unary
+[`avoid-breaking-exported-api`]: https://doc.rust-lang.org/clippy/lint_configuration.html#avoid-breaking-exported-api
+[`msrv`]: https://doc.rust-lang.org/clippy/lint_configuration.html#msrv
+[`cognitive-complexity-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#cognitive-complexity-threshold
+[`excessive-nesting-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#excessive-nesting-threshold
+[`disallowed-names`]: https://doc.rust-lang.org/clippy/lint_configuration.html#disallowed-names
+[`semicolon-inside-block-ignore-singleline`]: https://doc.rust-lang.org/clippy/lint_configuration.html#semicolon-inside-block-ignore-singleline
+[`semicolon-outside-block-ignore-multiline`]: https://doc.rust-lang.org/clippy/lint_configuration.html#semicolon-outside-block-ignore-multiline
+[`doc-valid-idents`]: https://doc.rust-lang.org/clippy/lint_configuration.html#doc-valid-idents
+[`too-many-arguments-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#too-many-arguments-threshold
+[`type-complexity-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#type-complexity-threshold
+[`single-char-binding-names-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#single-char-binding-names-threshold
+[`too-large-for-stack`]: https://doc.rust-lang.org/clippy/lint_configuration.html#too-large-for-stack
+[`enum-variant-name-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#enum-variant-name-threshold
+[`enum-variant-size-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#enum-variant-size-threshold
+[`verbose-bit-mask-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#verbose-bit-mask-threshold
+[`literal-representation-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#literal-representation-threshold
+[`trivial-copy-size-limit`]: https://doc.rust-lang.org/clippy/lint_configuration.html#trivial-copy-size-limit
+[`pass-by-value-size-limit`]: https://doc.rust-lang.org/clippy/lint_configuration.html#pass-by-value-size-limit
+[`too-many-lines-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#too-many-lines-threshold
+[`array-size-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#array-size-threshold
+[`stack-size-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#stack-size-threshold
+[`vec-box-size-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#vec-box-size-threshold
+[`max-trait-bounds`]: https://doc.rust-lang.org/clippy/lint_configuration.html#max-trait-bounds
+[`max-struct-bools`]: https://doc.rust-lang.org/clippy/lint_configuration.html#max-struct-bools
+[`max-fn-params-bools`]: https://doc.rust-lang.org/clippy/lint_configuration.html#max-fn-params-bools
+[`warn-on-all-wildcard-imports`]: https://doc.rust-lang.org/clippy/lint_configuration.html#warn-on-all-wildcard-imports
+[`disallowed-macros`]: https://doc.rust-lang.org/clippy/lint_configuration.html#disallowed-macros
+[`disallowed-methods`]: https://doc.rust-lang.org/clippy/lint_configuration.html#disallowed-methods
+[`disallowed-types`]: https://doc.rust-lang.org/clippy/lint_configuration.html#disallowed-types
+[`unreadable-literal-lint-fractions`]: https://doc.rust-lang.org/clippy/lint_configuration.html#unreadable-literal-lint-fractions
+[`upper-case-acronyms-aggressive`]: https://doc.rust-lang.org/clippy/lint_configuration.html#upper-case-acronyms-aggressive
+[`matches-for-let-else`]: https://doc.rust-lang.org/clippy/lint_configuration.html#matches-for-let-else
+[`cargo-ignore-publish`]: https://doc.rust-lang.org/clippy/lint_configuration.html#cargo-ignore-publish
+[`standard-macro-braces`]: https://doc.rust-lang.org/clippy/lint_configuration.html#standard-macro-braces
+[`enforced-import-renames`]: https://doc.rust-lang.org/clippy/lint_configuration.html#enforced-import-renames
+[`allowed-scripts`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allowed-scripts
+[`enable-raw-pointer-heuristic-for-send`]: https://doc.rust-lang.org/clippy/lint_configuration.html#enable-raw-pointer-heuristic-for-send
+[`max-suggested-slice-pattern-length`]: https://doc.rust-lang.org/clippy/lint_configuration.html#max-suggested-slice-pattern-length
+[`await-holding-invalid-types`]: https://doc.rust-lang.org/clippy/lint_configuration.html#await-holding-invalid-types
+[`max-include-file-size`]: https://doc.rust-lang.org/clippy/lint_configuration.html#max-include-file-size
+[`allow-expect-in-tests`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allow-expect-in-tests
+[`allow-unwrap-in-tests`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allow-unwrap-in-tests
+[`allow-dbg-in-tests`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allow-dbg-in-tests
+[`allow-print-in-tests`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allow-print-in-tests
+[`large-error-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#large-error-threshold
+[`ignore-interior-mutability`]: https://doc.rust-lang.org/clippy/lint_configuration.html#ignore-interior-mutability
+[`allow-mixed-uninlined-format-args`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allow-mixed-uninlined-format-args
+[`suppress-restriction-lint-in-const`]: https://doc.rust-lang.org/clippy/lint_configuration.html#suppress-restriction-lint-in-const
+[`missing-docs-in-crate-items`]: https://doc.rust-lang.org/clippy/lint_configuration.html#missing-docs-in-crate-items
+[`future-size-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#future-size-threshold
+[`unnecessary-box-size`]: https://doc.rust-lang.org/clippy/lint_configuration.html#unnecessary-box-size
+[`allow-private-module-inception`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allow-private-module-inception
+[`allowed-idents-below-min-chars`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allowed-idents-below-min-chars
+[`min-ident-chars-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#min-ident-chars-threshold
+<!-- end autogenerated links to configuration documentation -->

clippy_lints/src/utils/internal_lints/metadata_collector.rs

@@ -104,6 +104,8 @@ const APPLICABILITY_UNRESOLVED_STR: &str = "Unresolved";
 /// The version that will be displayed if none has been defined
 const VERSION_DEFAULT_STR: &str = "Unknown";
 
+const CHANGELOG_PATH: &str = "../CHANGELOG.md";
+
 declare_clippy_lint! {
     /// ### What it does
     /// Collects metadata about clippy lints for the website.
@@ -260,6 +262,22 @@ Please use that command to update the file and do not edit it by hand.
             self.get_markdown_docs(),
         )
         .unwrap();
+
+        // Write configuration links to CHANGELOG.md
+        let mut changelog = std::fs::read_to_string(CHANGELOG_PATH).unwrap();
+        let mut changelog_file = OpenOptions::new().read(true).write(true).open(CHANGELOG_PATH).unwrap();
+
+        if let Some(position) = changelog.find("<!-- begin autogenerated links to configuration documentation -->") {
+            // I know this is kinda wasteful, we just don't have regex on `clippy_lints` so... this is the best
+            // we can do AFAIK.
+            changelog = changelog[..position].to_string();
+        }
+        writeln!(
+            changelog_file,
+            "{changelog}<!-- begin autogenerated links to configuration documentation -->\n{}\n<!-- end autogenerated links to configuration documentation -->",
+            self.configs_to_markdown(ClippyConfiguration::to_markdown_link)
+        )
+        .unwrap();
     }
 }
 

clippy_lints/src/utils/mod.rs

@@ -12,6 +12,9 @@ fn to_kebab(config_name: &str) -> String {
     config_name.replace('_', "-")
 }
 
+#[cfg(feature = "internal")]
+const BOOK_CONFIGS_PATH: &str = "https://doc.rust-lang.org/clippy/lint_configuration.html";
+
 // ==================================================================
 // Configuration
 // ==================================================================
@@ -66,6 +69,10 @@ impl ClippyConfiguration {
                 .join("\n"),
         )
     }
+    #[cfg(feature = "internal")]
+    fn to_markdown_link(&self) -> String {
+        format!("[`{}`]: {BOOK_CONFIGS_PATH}#{}", self.name, self.name)
+    }
 }
 
 #[cfg(feature = "internal")]