Auto merge of #10199 - tylerjw:document-extending-list-configs, r=xFrednet

Document lint configuration values in Clippy's book

changelog: document lint configuration values in Clippy's book

fixes #9991

r? `@xFrednet`

clippy_lints/src/utils/conf.rs

@@ -219,7 +219,8 @@ define_Conf! {
     ///
     /// #### Noteworthy
     ///
-    /// A type, say `SomeType`, listed in this configuration has the same behavior of `["SomeType" , "*"], ["*", "SomeType"]` in `arithmetic_side_effects_allowed_binary`.
+    /// A type, say `SomeType`, listed in this configuration has the same behavior of
+    /// `["SomeType" , "*"], ["*", "SomeType"]` in `arithmetic_side_effects_allowed_binary`.
     (arithmetic_side_effects_allowed: rustc_data_structures::fx::FxHashSet<String> = <_>::default()),
     /// Lint: ARITHMETIC_SIDE_EFFECTS.
     ///

clippy_lints/src/utils/internal_lints/metadata_collector.rs

@@ -14,6 +14,7 @@ use clippy_utils::diagnostics::span_lint;
 use clippy_utils::ty::{match_type, walk_ptrs_ty_depth};
 use clippy_utils::{last_path_segment, match_def_path, match_function_call, match_path, paths};
 use if_chain::if_chain;
+use itertools::Itertools;
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::{
@@ -34,8 +35,10 @@ use std::path::Path;
 use std::path::PathBuf;
 use std::process::Command;
 
-/// This is the output file of the lint collector.
-const OUTPUT_FILE: &str = "../util/gh-pages/lints.json";
+/// This is the json output file of the lint collector.
+const JSON_OUTPUT_FILE: &str = "../util/gh-pages/lints.json";
+/// This is the markdown output file of the lint collector.
+const MARKDOWN_OUTPUT_FILE: &str = "../book/src/lint_configuration.md";
 /// These lints are excluded from the export.
 const BLACK_LISTED_LINTS: &[&str] = &["lint_author", "dump_hir", "internal_metadata_collector"];
 /// These groups will be ignored by the lint group matcher. This is useful for collections like
@@ -176,6 +179,23 @@ This lint has the following configuration variables:
                 )
             })
     }
+
+    fn configs_to_markdown(&self, map_fn: fn(&ClippyConfiguration) -> String) -> String {
+        self.config
+            .iter()
+            .filter(|config| config.deprecation_reason.is_none())
+            .filter(|config| !config.lints.is_empty())
+            .map(map_fn)
+            .join("\n")
+    }
+
+    fn get_markdown_docs(&self) -> String {
+        format!(
+            "## Lint Configuration Options\n| <div style=\"width:290px\">Option</div> | Default Value |\n|--|--|\n{}\n\n{}\n",
+            self.configs_to_markdown(ClippyConfiguration::to_markdown_table_entry),
+            self.configs_to_markdown(ClippyConfiguration::to_markdown_paragraph),
+        )
+    }
 }
 
 impl Drop for MetadataCollector {
@@ -199,12 +219,37 @@ impl Drop for MetadataCollector {
 
         collect_renames(&mut lints);
 
-        // Outputting
-        if Path::new(OUTPUT_FILE).exists() {
-            fs::remove_file(OUTPUT_FILE).unwrap();
+        // Outputting json
+        if Path::new(JSON_OUTPUT_FILE).exists() {
+            fs::remove_file(JSON_OUTPUT_FILE).unwrap();
         }
-        let mut file = OpenOptions::new().write(true).create(true).open(OUTPUT_FILE).unwrap();
+        let mut file = OpenOptions::new()
+            .write(true)
+            .create(true)
+            .open(JSON_OUTPUT_FILE)
+            .unwrap();
         writeln!(file, "{}", serde_json::to_string_pretty(&lints).unwrap()).unwrap();
+
+        // Outputting markdown
+        if Path::new(MARKDOWN_OUTPUT_FILE).exists() {
+            fs::remove_file(MARKDOWN_OUTPUT_FILE).unwrap();
+        }
+        let mut file = OpenOptions::new()
+            .write(true)
+            .create(true)
+            .open(MARKDOWN_OUTPUT_FILE)
+            .unwrap();
+        writeln!(
+            file,
+            "<!--
+This file is generated by `cargo collect-metadata`.
+Please use that command to update the file and do not edit it by hand.
+-->
+
+{}",
+            self.get_markdown_docs(),
+        )
+        .unwrap();
     }
 }
 
@@ -505,6 +550,28 @@ impl ClippyConfiguration {
             deprecation_reason,
         }
     }
+
+    fn to_markdown_paragraph(&self) -> String {
+        format!(
+            "### {}\n{}\n\n**Default Value:** `{}` (`{}`)\n\n{}\n\n",
+            self.name,
+            self.doc
+                .lines()
+                .map(|line| line.strip_prefix("    ").unwrap_or(line))
+                .join("\n"),
+            self.default,
+            self.config_type,
+            self.lints
+                .iter()
+                .map(|name| name.to_string().split_whitespace().next().unwrap().to_string())
+                .map(|name| format!("* [{name}](https://rust-lang.github.io/rust-clippy/master/index.html#{name})"))
+                .join("\n"),
+        )
+    }
+
+    fn to_markdown_table_entry(&self) -> String {
+        format!("| [{}](#{}) | `{}` |", self.name, self.name, self.default)
+    }
 }
 
 fn collect_configs() -> Vec<ClippyConfiguration> {