[WIP] add support for minimum supported rust version. fixes rust-lang#6097

add configuration option for minimum supported rust version
add msrv attribute to  lints listed in rust-lang#6097
generify `LimitStack` for use in other lints
update the `cognitive_complexity` lint to use a `LimitStack<u64>`
update existing tests with the msrv attribute

Author: suyashb95

clippy_lints/src/cognitive_complexity.rs

@@ -27,7 +27,7 @@ declare_clippy_lint! {
 }
 
 pub struct CognitiveComplexity {
-    limit: LimitStack,
+    limit: LimitStack<u64>,
 }
 
 impl CognitiveComplexity {
@@ -74,7 +74,7 @@ impl CognitiveComplexity {
             rust_cc -= ret_adjust;
         }
 
-        if rust_cc > self.limit.limit() {
+        if rust_cc > *self.limit.limit() {
             let fn_span = match kind {
                 FnKind::ItemFn(ident, _, _, _, _) | FnKind::Method(ident, _, _, _) => ident.span,
                 FnKind::Closure(_) => {

clippy_lints/src/lib.rs

@@ -920,7 +920,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &zero_div_zero::ZERO_DIVIDED_BY_ZERO,
     ]);
     // end register lints, do not remove this comment, it’s used in `update_lints`
-
     store.register_late_pass(|| box await_holding_invalid::AwaitHolding);
     store.register_late_pass(|| box serde_api::SerdeAPI);
     store.register_late_pass(|| box utils::internal_lints::CompilerLintFunctions::new());
@@ -956,7 +955,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box strings::StringAdd);
     store.register_late_pass(|| box implicit_return::ImplicitReturn);
     store.register_late_pass(|| box implicit_saturating_sub::ImplicitSaturatingSub);
-    store.register_late_pass(|| box methods::Methods);
+    let msrv = conf.msrv.clone();
+    store.register_late_pass(move || box methods::Methods::new(String::from(msrv.clone())));
     store.register_late_pass(|| box map_clone::MapClone);
     store.register_late_pass(|| box map_err_ignore::MapErrIgnore);
     store.register_late_pass(|| box shadow::Shadow);
@@ -970,7 +970,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box types::Casts);
     let type_complexity_threshold = conf.type_complexity_threshold;
     store.register_late_pass(move || box types::TypeComplexity::new(type_complexity_threshold));
-    store.register_late_pass(|| box matches::Matches::default());
+    let msrv = conf.msrv.clone();
+    store.register_late_pass(move || box matches::Matches::new(String::from(msrv.clone())));
     store.register_late_pass(|| box minmax::MinMaxPass);
     store.register_late_pass(|| box open_options::OpenOptions);
     store.register_late_pass(|| box zero_div_zero::ZeroDiv);
@@ -1129,7 +1130,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box if_let_mutex::IfLetMutex);
     store.register_late_pass(|| box mut_mutex_lock::MutMutexLock);
     store.register_late_pass(|| box match_on_vec_items::MatchOnVecItems);
-    store.register_early_pass(|| box manual_non_exhaustive::ManualNonExhaustive);
+    let msrv = conf.msrv.clone();
+    store.register_early_pass(move || box manual_non_exhaustive::ManualNonExhaustive::new(String::from(msrv.clone())));
     store.register_late_pass(|| box manual_async_fn::ManualAsyncFn);
     store.register_early_pass(|| box redundant_field_names::RedundantFieldNames);
     store.register_late_pass(|| box vec_resize_to_zero::VecResizeToZero);
@@ -1150,7 +1152,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box manual_unwrap_or::ManualUnwrapOr);
     store.register_late_pass(|| box float_equality_without_abs::FloatEqualityWithoutAbs);
     store.register_late_pass(|| box async_yields_async::AsyncYieldsAsync);
-    store.register_late_pass(|| box manual_strip::ManualStrip);
+    let msrv = conf.msrv.clone();
+    store.register_late_pass(move || box manual_strip::ManualStrip::new(String::from(msrv.clone())));
     store.register_late_pass(|| box utils::internal_lints::MatchTypeOnDiagItem);
     let disallowed_methods = conf.disallowed_methods.iter().cloned().collect::<FxHashSet<_>>();
     store.register_late_pass(move || box disallowed_method::DisallowedMethod::new(&disallowed_methods));

clippy_lints/src/manual_non_exhaustive.rs

@@ -1,11 +1,14 @@
-use crate::utils::{snippet_opt, span_lint_and_then};
+use crate::utils::{snippet_opt, span_lint_and_then, LimitStack};
 use if_chain::if_chain;
 use rustc_ast::ast::{Attribute, Item, ItemKind, StructField, Variant, VariantData, VisibilityKind};
 use rustc_attr as attr;
 use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass};
-use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::Span;
+use semver::Version;
+
+const MANUAL_NON_EXHAUSTIVE_MSRV: &str = "1.40.0";
 
 declare_clippy_lint! {
     /// **What it does:** Checks for manual implementations of the non-exhaustive pattern.
@@ -55,10 +58,28 @@ declare_clippy_lint! {
     "manual implementations of the non-exhaustive pattern can be simplified using #[non_exhaustive]"
 }
 
-declare_lint_pass!(ManualNonExhaustive => [MANUAL_NON_EXHAUSTIVE]);
+#[derive(Clone)]
+pub struct ManualNonExhaustive {
+    msrv_stack: LimitStack<String>,
+}
+
+impl ManualNonExhaustive {
+    #[must_use]
+    pub fn new(msrv: String) -> Self {
+        Self {
+            msrv_stack: LimitStack::new(msrv),
+        }
+    }
+}
+
+impl_lint_pass!(ManualNonExhaustive => [MANUAL_NON_EXHAUSTIVE]);
 
 impl EarlyLintPass for ManualNonExhaustive {
     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
+        if Version::parse(&self.msrv_stack.limit()) < Version::parse(MANUAL_NON_EXHAUSTIVE_MSRV) {
+            return;
+        }
+
         match &item.kind {
             ItemKind::Enum(def, _) => {
                 check_manual_non_exhaustive_enum(cx, item, &def.variants);
@@ -73,6 +94,14 @@ impl EarlyLintPass for ManualNonExhaustive {
             _ => {},
         }
     }
+
+    fn enter_lint_attrs(&mut self, cx: &EarlyContext<'tcx>, attrs: &'tcx [Attribute]) {
+        self.msrv_stack.push_attrs(cx.sess, attrs, "msrv");
+    }
+
+    fn exit_lint_attrs(&mut self, cx: &EarlyContext<'tcx>, attrs: &'tcx [Attribute]) {
+        self.msrv_stack.pop_attrs(cx.sess, attrs, "msrv");
+    }
 }
 
 fn check_manual_non_exhaustive_enum(cx: &EarlyContext<'_>, item: &Item, variants: &[Variant]) {

clippy_lints/src/manual_strip.rs

@@ -1,21 +1,24 @@
 use crate::consts::{constant, Constant};
 use crate::utils::usage::mutated_variables;
 use crate::utils::{
-    eq_expr_value, higher, match_def_path, multispan_sugg, paths, qpath_res, snippet, span_lint_and_then,
+    eq_expr_value, higher, match_def_path, multispan_sugg, paths, qpath_res, snippet, span_lint_and_then, LimitStack,
 };
 
 use if_chain::if_chain;
-use rustc_ast::ast::LitKind;
+use rustc_ast::ast::{Attribute, LitKind};
 use rustc_hir::def::Res;
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::BinOpKind;
 use rustc_hir::{BorrowKind, Expr, ExprKind};
-use rustc_lint::{LateContext, LateLintPass};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::hir::map::Map;
 use rustc_middle::ty;
-use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Spanned;
 use rustc_span::Span;
+use semver::Version;
+
+const MANUAL_STRIP_MSRV: &str = "1.45.0";
 
 declare_clippy_lint! {
     /// **What it does:**
@@ -51,7 +54,20 @@ declare_clippy_lint! {
     "suggests using `strip_{prefix,suffix}` over `str::{starts,ends}_with` and slicing"
 }
 
-declare_lint_pass!(ManualStrip => [MANUAL_STRIP]);
+pub struct ManualStrip {
+    msrv_stack: LimitStack<String>,
+}
+
+impl ManualStrip {
+    #[must_use]
+    pub fn new(msrv: String) -> Self {
+        Self {
+            msrv_stack: LimitStack::new(msrv),
+        }
+    }
+}
+
+impl_lint_pass!(ManualStrip => [MANUAL_STRIP]);
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 enum StripKind {
@@ -61,6 +77,10 @@ enum StripKind {
 
 impl<'tcx> LateLintPass<'tcx> for ManualStrip {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        if Version::parse(&self.msrv_stack.limit()) < Version::parse(MANUAL_STRIP_MSRV) {
+            return;
+        }
+
         if_chain! {
             if let Some((cond, then, _)) = higher::if_block(&expr);
             if let ExprKind::MethodCall(_, _, [target_arg, pattern], _) = cond.kind;
@@ -114,6 +134,14 @@ impl<'tcx> LateLintPass<'tcx> for ManualStrip {
             }
         }
     }
+
+    fn enter_lint_attrs(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) {
+        self.msrv_stack.push_attrs(cx.sess(), attrs, "msrv");
+    }
+
+    fn exit_lint_attrs(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) {
+        self.msrv_stack.pop_attrs(cx.sess(), attrs, "msrv");
+    }
 }
 
 // Returns `Some(arg)` if `expr` matches `arg.len()` and `None` otherwise.

clippy_lints/src/matches.rs

@@ -5,11 +5,11 @@ use crate::utils::{
     expr_block, get_arg_name, get_parent_expr, in_macro, indent_of, is_allowed, is_expn_of, is_refutable,
     is_type_diagnostic_item, is_wild, match_qpath, match_type, match_var, multispan_sugg, remove_blocks, snippet,
     snippet_block, snippet_with_applicability, span_lint_and_help, span_lint_and_note, span_lint_and_sugg,
-    span_lint_and_then,
+    span_lint_and_then, LimitStack,
 };
 use crate::utils::{paths, search_same, SpanlessEq, SpanlessHash};
 use if_chain::if_chain;
-use rustc_ast::ast::LitKind;
+use rustc_ast::ast::{Attribute, LitKind};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::Applicability;
 use rustc_hir::def::CtorKind;
@@ -23,6 +23,7 @@ use rustc_middle::ty::{self, Ty, TyS};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::{Span, Spanned};
 use rustc_span::Symbol;
+use semver::Version;
 use std::cmp::Ordering;
 use std::collections::hash_map::Entry;
 use std::collections::Bound;
@@ -521,9 +522,20 @@ declare_clippy_lint! {
 
 #[derive(Default)]
 pub struct Matches {
+    msrv_stack: LimitStack<String>,
     infallible_destructuring_match_linted: bool,
 }
 
+impl Matches {
+    #[must_use]
+    pub fn new(msrv: String) -> Self {
+        Self {
+            msrv_stack: LimitStack::new(msrv),
+            ..Default::default()
+        }
+    }
+}
+
 impl_lint_pass!(Matches => [
     SINGLE_MATCH,
     MATCH_REF_PATS,
@@ -543,15 +555,20 @@ impl_lint_pass!(Matches => [
     MATCH_SAME_ARMS,
 ]);
 
+const MATCH_LIKE_MATCHES_MACRO_MSRV: &str = "1.42.0";
+
 impl<'tcx> LateLintPass<'tcx> for Matches {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if in_external_macro(cx.sess(), expr.span) || in_macro(expr.span) {
             return;
         }
 
         redundant_pattern_match::check(cx, expr);
-        if !check_match_like_matches(cx, expr) {
-            lint_match_arms(cx, expr);
+
+        if Version::parse(&self.msrv_stack.limit()) >= Version::parse(MATCH_LIKE_MATCHES_MACRO_MSRV) {
+            if !check_match_like_matches(cx, expr) {
+                lint_match_arms(cx, expr);
+            }
         }
 
         if let ExprKind::Match(ref ex, ref arms, MatchSource::Normal) = expr.kind {
@@ -634,6 +651,14 @@ impl<'tcx> LateLintPass<'tcx> for Matches {
             }
         }
     }
+
+    fn enter_lint_attrs(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) {
+        self.msrv_stack.push_attrs(cx.sess(), attrs, "msrv");
+    }
+
+    fn exit_lint_attrs(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) {
+        self.msrv_stack.pop_attrs(cx.sess(), attrs, "msrv");
+    }
 }
 
 #[rustfmt::skip]

clippy_lints/src/methods/mod.rs

@@ -12,6 +12,7 @@ use std::iter;
 use bind_instead_of_map::BindInsteadOfMap;
 use if_chain::if_chain;
 use rustc_ast::ast;
+use rustc_ast::ast::Attribute;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::intravisit::{self, Visitor};
@@ -20,9 +21,10 @@ use rustc_lint::{LateContext, LateLintPass, Lint, LintContext};
 use rustc_middle::hir::map::Map;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::{self, TraitRef, Ty, TyS};
-use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
 use rustc_span::symbol::{sym, SymbolStr};
+use semver::Version;
 
 use crate::consts::{constant, Constant};
 use crate::utils::eager_or_lazy::is_lazyness_candidate;
@@ -32,7 +34,8 @@ use crate::utils::{
     is_copy, is_expn_of, is_type_diagnostic_item, iter_input_pats, last_path_segment, match_def_path, match_qpath,
     match_trait_method, match_type, match_var, method_calls, method_chain_args, paths, remove_blocks, return_ty,
     single_segment_path, snippet, snippet_with_applicability, snippet_with_macro_callsite, span_lint,
-    span_lint_and_help, span_lint_and_sugg, span_lint_and_then, sugg, walk_ptrs_ty_depth, SpanlessEq,
+    span_lint_and_help, span_lint_and_sugg, span_lint_and_then, sugg, walk_ptrs_ty_depth,
+    LimitStack, SpanlessEq,
 };
 
 declare_clippy_lint! {
@@ -1369,7 +1372,20 @@ declare_clippy_lint! {
     "using `.map(_).collect::<Result<(),_>()`, which can be replaced with `try_for_each`"
 }
 
-declare_lint_pass!(Methods => [
+pub struct Methods {
+    msrv_stack: LimitStack<String>,
+}
+
+impl Methods {
+    #[must_use]
+    pub fn new(msrv: String) -> Self {
+        Self {
+            msrv_stack: LimitStack::new(msrv.clone()),
+        }
+    }
+}
+
+impl_lint_pass!(Methods => [
     UNWRAP_USED,
     EXPECT_USED,
     SHOULD_IMPLEMENT_TRAIT,
@@ -1495,8 +1511,10 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
                 check_pointer_offset(cx, expr, arg_lists[0])
             },
             ["is_file", ..] => lint_filetype_is_file(cx, expr, arg_lists[0]),
-            ["map", "as_ref"] => lint_option_as_ref_deref(cx, expr, arg_lists[1], arg_lists[0], false),
-            ["map", "as_mut"] => lint_option_as_ref_deref(cx, expr, arg_lists[1], arg_lists[0], true),
+            ["map", "as_ref"] => {
+                lint_option_as_ref_deref(cx, expr, arg_lists[1], arg_lists[0], false, &self.msrv_stack)
+            },
+            ["map", "as_mut"] => lint_option_as_ref_deref(cx, expr, arg_lists[1], arg_lists[0], true, &self.msrv_stack),
             ["unwrap_or_else", ..] => unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "unwrap_or"),
             ["get_or_insert_with", ..] => unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "get_or_insert"),
             ["ok_or_else", ..] => unnecessary_lazy_eval::lint(cx, expr, arg_lists[0], "ok_or"),
@@ -1693,6 +1711,14 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
             }
         }
     }
+
+    fn enter_lint_attrs(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) {
+        self.msrv_stack.push_attrs(cx.sess(), attrs, "msrv");
+    }
+
+    fn exit_lint_attrs(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) {
+        self.msrv_stack.pop_attrs(cx.sess(), attrs, "msrv");
+    }
 }
 
 /// Checks for the `OR_FUN_CALL` lint.
@@ -3364,14 +3390,21 @@ fn lint_suspicious_map(cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
     );
 }
 
+const OPTION_AS_REF_DEREF_MSRV: &str = "1.40.0";
+
 /// lint use of `_.as_ref().map(Deref::deref)` for `Option`s
 fn lint_option_as_ref_deref<'tcx>(
     cx: &LateContext<'tcx>,
     expr: &hir::Expr<'_>,
     as_ref_args: &[hir::Expr<'_>],
     map_args: &[hir::Expr<'_>],
     is_mut: bool,
+    msrv_stack: &LimitStack<String>,
 ) {
+    if Version::parse(&msrv_stack.limit()) < Version::parse(OPTION_AS_REF_DEREF_MSRV) {
+        return;
+    }
+
     let same_mutability = |m| (is_mut && m == &hir::Mutability::Mut) || (!is_mut && m == &hir::Mutability::Not);
 
     let option_ty = cx.typeck_results().expr_ty(&as_ref_args[0]);