Auto merge of #16401 - Urhengulas:lint-table, r=Veykril

Expand lint tables && make clippy happy 🎉

This PR expands the lint tables on `./Cargo.toml` and thereby makes `cargo clippy` exit successfully! 🎉

Fixes #15918

## How?

In the beginning there are some warnings for rustc.

Next, and most importantly, there is the clippy lint table. There are a few sections in there.

First there are the lint groups.

Second there are all lints which are permanently allowed with the reasoning why they are allowed.

Third there is a huge list of temporarily allowed lints. They should be removed in the mid-term, but incur a substantial amount of work, therefore they are allowed for now and can be worked on bit by bit.

Fourth there are all lints which should warn.

Additionally there are a few allow statements in the code for lints which should be permanently allowed in this specific place, but not in the whole code base.

## Follow up work
- [ ] Run clippy in CI
- [ ] Remove tidy test (at least `@Veykril` wrote this in #15017)
- [ ] Work on temporarily allowed lints

9 files changed, 103 insertions, 4 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 5f8bd61015e..9564aaeccab 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -105,7 +105,7 @@ dissimilar = "1.0.7"
 either = "1.9.0"
 expect-test = "1.4.0"
 hashbrown = { version = "0.14", features = [
-  "inline-more",
+    "inline-more",
 ], default-features = false }
 indexmap = "2.1.0"
 itertools = "0.12.0"
@@ -118,9 +118,9 @@ semver = "1.0.14"
 serde = { version = "1.0.192", features = ["derive"] }
 serde_json = "1.0.108"
 smallvec = { version = "1.10.0", features = [
-  "const_new",
-  "union",
-  "const_generics",
+    "const_new",
+    "union",
+    "const_generics",
 ] }
 smol_str = "0.2.1"
 text-size = "1.1.1"
@@ -138,8 +138,97 @@ xshell = "0.2.5"
 # We need to freeze the version of the crate, as the raw-api feature is considered unstable
 dashmap = { version = "=5.5.3", features = ["raw-api"] }
 
+[workspace.lints.rust]
+rust_2018_idioms = "warn"
+unused_lifetimes = "warn"
+semicolon_in_expressions_from_macros = "warn"
+
 [workspace.lints.clippy]
+# FIXME Remove the tidy test once the lint table is stable
+
+## lint groups
+complexity = { level = "warn", priority = -1 }
+correctness = { level = "deny", priority = -1 }
+perf = { level = "deny", priority = -1 }
+restriction = { level = "allow", priority = -1 }
+style = { level = "warn", priority = -1 }
+suspicious = { level = "warn", priority = -1 }
+
+## allow following lints
+# () makes a fine error in most cases
+result_unit_err = "allow"
+# We don't expose public APIs that matter like this
+len_without_is_empty = "allow"
+# We currently prefer explicit control flow return over `...?;` statements whose result is unused
+question_mark = "allow"
+# We have macros that rely on this currently
+enum_variant_names = "allow"
+# Builder pattern disagrees
+new_ret_no_self = "allow"
+
+## Following lints should be tackled at some point
+bind_instead_of_map = "allow"
+borrowed_box = "allow"
+borrow_deref_ref = "allow"
 collapsible_if = "allow"
+collapsible_match = "allow"
+clone_on_copy = "allow"
+derivable_impls = "allow"
+derived_hash_with_manual_eq = "allow"
+double_parens = "allow"
+explicit_auto_deref = "allow"
+field_reassign_with_default = "allow"
+forget_non_drop = "allow"
+format_collect = "allow"
+for_kv_map = "allow"
+filter_map_bool_then = "allow"
+from_str_radix_10 = "allow"
+get_first = "allow"
+if_same_then_else = "allow"
+large_enum_variant = "allow"
+let_and_return = "allow"
+manual_find = "allow"
+manual_map = "allow"
+map_clone = "allow"
+match_like_matches_macro = "allow"
+match_single_binding = "allow"
+needless_borrow = "allow"
+needless_doctest_main = "allow"
+needless_lifetimes = "allow"
 needless_pass_by_value = "allow"
+needless_return = "allow"
+new_without_default = "allow"
 nonminimal_bool = "allow"
+non_canonical_clone_impl = "allow"
+non_canonical_partial_ord_impl = "allow"
+non_minimal_cfg = "allow"
+only_used_in_recursion = "allow"
+op_ref = "allow"
+option_map_unit_fn = "allow"
+partialeq_to_none = "allow"
+ptr_arg = "allow"
+redundant_closure = "allow"
 redundant_pattern_matching = "allow"
+search_is_some = "allow"
+self_named_constructors = "allow"
+single_match = "allow"
+skip_while_next = "allow"
+too_many_arguments = "allow"
+toplevel_ref_arg = "allow"
+type_complexity = "allow"
+unnecessary_cast = "allow"
+unnecessary_filter_map = "allow"
+unnecessary_lazy_evaluations = "allow"
+unnecessary_mut_passed = "allow"
+useless_conversion = "allow"
+useless_format = "allow"
+wildcard_in_or_patterns = "allow"
+wrong_self_convention = "allow"
+
+## warn at following lints
+dbg_macro = "warn"
+todo = "warn"
+unimplemented = "allow"
+rc_buffer = "warn"
+# FIXME enable this, we use this pattern a lot so its annoying work ...
+# str_to_string = "warn"
diff --git a/crates/base-db/src/input.rs b/crates/base-db/src/input.rs
index 3f84657d011..1fa5f33575e 100644
--- a/crates/base-db/src/input.rs
+++ b/crates/base-db/src/input.rs
@@ -261,6 +261,7 @@ impl ReleaseChannel {
         }
     }
 
+    #[allow(clippy::should_implement_trait)]
     pub fn from_str(str: &str) -> Option<Self> {
         Some(match str {
             "" | "stable" => ReleaseChannel::Stable,
diff --git a/crates/hir-def/src/lang_item.rs b/crates/hir-def/src/lang_item.rs
index adb2d785439..dd2e8735573 100644
--- a/crates/hir-def/src/lang_item.rs
+++ b/crates/hir-def/src/lang_item.rs
@@ -260,6 +260,7 @@ macro_rules! language_item_table {
             }
 
             /// Opposite of [`LangItem::name`]
+            #[allow(clippy::should_implement_trait)]
             pub fn from_str(name: &str) -> Option<Self> {
                 match name {
                     $( stringify!($name) => Some(LangItem::$variant), )*
diff --git a/crates/hir-expand/src/builtin_fn_macro.rs b/crates/hir-expand/src/builtin_fn_macro.rs
index 8fc78b3eca9..29d389f656f 100644
--- a/crates/hir-expand/src/builtin_fn_macro.rs
+++ b/crates/hir-expand/src/builtin_fn_macro.rs
@@ -392,6 +392,7 @@ fn unreachable_expand(
     ExpandResult::ok(call)
 }
 
+#[allow(clippy::never_loop)]
 fn use_panic_2021(db: &dyn ExpandDatabase, span: Span) -> bool {
     // To determine the edition, we check the first span up the expansion
     // stack that does not have #[allow_internal_unstable(edition_panic)].
diff --git a/crates/hir-expand/src/quote.rs b/crates/hir-expand/src/quote.rs
index 04b427e8b49..824f3c3e8f2 100644
--- a/crates/hir-expand/src/quote.rs
+++ b/crates/hir-expand/src/quote.rs
@@ -1,4 +1,5 @@
 //! A simplified version of quote-crate like quasi quote macro
+#![allow(clippy::crate_in_macro_def)]
 
 use span::Span;
 use syntax::format_smolstr;
diff --git a/crates/ide/src/syntax_tree.rs b/crates/ide/src/syntax_tree.rs
index df197124265..a4aed609694 100644
--- a/crates/ide/src/syntax_tree.rs
+++ b/crates/ide/src/syntax_tree.rs
@@ -52,6 +52,7 @@ fn syntax_tree_for_string(token: &SyntaxToken, text_range: TextRange) -> Option<
     }
 }
 
+#[allow(clippy::redundant_locals)]
 fn syntax_tree_for_token(node: &SyntaxToken, text_range: TextRange) -> Option<String> {
     // Range of the full node
     let node_range = node.text_range();
diff --git a/crates/rust-analyzer/src/cli/rustc_tests.rs b/crates/rust-analyzer/src/cli/rustc_tests.rs
index baa85d3295d..df0c2d497a6 100644
--- a/crates/rust-analyzer/src/cli/rustc_tests.rs
+++ b/crates/rust-analyzer/src/cli/rustc_tests.rs
@@ -226,6 +226,7 @@ const SUPPORTED_DIAGNOSTICS: &[DiagnosticCode] = &[
 ];
 
 impl flags::RustcTests {
+    #[allow(clippy::redundant_locals)]
     pub fn run(self) -> Result<()> {
         let mut tester = Tester::new()?;
         let walk_dir = WalkDir::new(self.rustc_repo.join("tests/ui"));
diff --git a/crates/span/src/lib.rs b/crates/span/src/lib.rs
index 54fc0225ae5..f6569050b4a 100644
--- a/crates/span/src/lib.rs
+++ b/crates/span/src/lib.rs
@@ -225,6 +225,7 @@ impl fmt::Debug for HirFileIdRepr {
 }
 
 impl From<FileId> for HirFileId {
+    #[allow(clippy::let_unit_value)]
     fn from(id: FileId) -> Self {
         _ = Self::ASSERT_MAX_FILE_ID_IS_SAME;
         assert!(id.index() <= Self::MAX_HIR_FILE_ID, "FileId index {} is too large", id.index());
@@ -233,6 +234,7 @@ impl From<FileId> for HirFileId {
 }
 
 impl From<MacroFileId> for HirFileId {
+    #[allow(clippy::let_unit_value)]
     fn from(MacroFileId { macro_call_id: MacroCallId(id) }: MacroFileId) -> Self {
         _ = Self::ASSERT_MAX_FILE_ID_IS_SAME;
         let id = id.as_u32();
diff --git a/lib/la-arena/src/map.rs b/lib/la-arena/src/map.rs
index 750f345b539..c6a43d8f9a6 100644
--- a/lib/la-arena/src/map.rs
+++ b/lib/la-arena/src/map.rs
@@ -252,6 +252,8 @@ where
 {
     /// Ensures a value is in the entry by inserting the default value if empty, and returns a mutable reference
     /// to the value in the entry.
+    // BUG this clippy lint is a false positive
+    #[allow(clippy::unwrap_or_default)]
     pub fn or_default(self) -> &'a mut V {
         self.or_insert_with(Default::default)
     }