add check.ignore to list cargo check diagnostics to ignore (dead_code, unused_imports, ...)

fixes #14798

crates/rust-analyzer/src/config.rs

@@ -150,6 +150,10 @@ config_data! {
         ///
         /// Set to `"all"` to pass `--all-features` to Cargo.
         check_features | checkOnSave_features: Option<CargoFeaturesDef>  = "null",
+        /// List of `cargo check` (or other command specified in `check.command`) diagnostics to ignore.
+        ///
+        /// For example for `cargo check`: `dead_code`, `unused_imports`, `unused_variables`,...
+        check_ignore: FxHashSet<String> = "[]",
         /// Specifies the working directory for running checks.
         /// - "workspace": run checks for workspaces in the corresponding workspaces' root directories.
         // FIXME: Ideally we would support this in some way
@@ -1098,6 +1102,7 @@ impl Config {
             remap_prefix: self.data.diagnostics_remapPrefix.clone(),
             warnings_as_info: self.data.diagnostics_warningsAsInfo.clone(),
             warnings_as_hint: self.data.diagnostics_warningsAsHint.clone(),
+            check_ignore: self.data.check_ignore.clone(),
         }
     }
 

crates/rust-analyzer/src/diagnostics.rs

@@ -6,6 +6,7 @@ use std::mem;
 use ide::FileId;
 use ide_db::FxHashMap;
 use nohash_hasher::{IntMap, IntSet};
+use rustc_hash::FxHashSet;
 use triomphe::Arc;
 
 use crate::lsp_ext;
@@ -17,6 +18,7 @@ pub struct DiagnosticsMapConfig {
     pub remap_prefix: FxHashMap<String, String>,
     pub warnings_as_info: Vec<String>,
     pub warnings_as_hint: Vec<String>,
+    pub check_ignore: FxHashSet<String>,
 }
 
 #[derive(Debug, Default, Clone)]

crates/rust-analyzer/src/diagnostics/to_proto.rs

@@ -292,6 +292,13 @@ pub(crate) fn map_rust_diagnostic_to_lsp(
 
     let mut source = String::from("rustc");
     let mut code = rd.code.as_ref().map(|c| c.code.clone());
+
+    if let Some(code_val) = &code {
+        if config.check_ignore.contains(code_val) {
+            return Vec::new();
+        }
+    }
+
     if let Some(code_val) = &code {
         // See if this is an RFC #2103 scoped lint (e.g. from Clippy)
         let scoped_code: Vec<&str> = code_val.split("::").collect();