Add MSRV check for saturating_sub lints in const contexts

Author: GuillaumeGomez

clippy_config/src/msrvs.rs

@@ -35,7 +35,7 @@ msrv_aliases! {
     1,52,0 { STR_SPLIT_ONCE, REM_EUCLID_CONST }
     1,51,0 { BORROW_AS_PTR, SEEK_FROM_CURRENT, UNSIGNED_ABS }
     1,50,0 { BOOL_THEN, CLAMP }
-    1,47,0 { TAU, IS_ASCII_DIGIT_CONST, ARRAY_IMPL_ANY_LEN }
+    1,47,0 { TAU, IS_ASCII_DIGIT_CONST, ARRAY_IMPL_ANY_LEN, SATURATING_SUB_CONST }
     1,46,0 { CONST_IF_MATCH }
     1,45,0 { STR_STRIP_PREFIX }
     1,43,0 { LOG2_10, LOG10_2, NUMERIC_ASSOCIATED_CONSTANTS }

clippy_lints/src/implicit_saturating_sub.rs

@@ -1,12 +1,16 @@
+use clippy_config::msrvs::{self, Msrv};
+use clippy_config::Conf;
 use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::source::snippet_opt;
-use clippy_utils::{higher, is_integer_literal, path_to_local, peel_blocks, peel_blocks_with_stmt, SpanlessEq};
+use clippy_utils::{
+    higher, in_constant, is_integer_literal, path_to_local, peel_blocks, peel_blocks_with_stmt, SpanlessEq,
+};
 use rustc_ast::ast::LitKind;
 use rustc_data_structures::packed::Pu128;
 use rustc_errors::Applicability;
 use rustc_hir::{BinOp, BinOpKind, Expr, ExprKind, HirId, QPath};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_session::declare_lint_pass;
+use rustc_session::impl_lint_pass;
 use rustc_span::Span;
 
 declare_clippy_lint! {
@@ -70,13 +74,28 @@ declare_clippy_lint! {
     "Check if a variable is smaller than another one and still subtract from it even if smaller"
 }
 
-declare_lint_pass!(ImplicitSaturatingSub => [IMPLICIT_SATURATING_SUB, INVERTED_SATURATING_SUB]);
+pub struct ImplicitSaturatingSub {
+    msrv: Msrv,
+}
+
+impl_lint_pass!(ImplicitSaturatingSub => [IMPLICIT_SATURATING_SUB, INVERTED_SATURATING_SUB]);
+
+impl ImplicitSaturatingSub {
+    pub fn new(conf: &'static Conf) -> Self {
+        Self {
+            msrv: conf.msrv.clone(),
+        }
+    }
+}
 
 impl<'tcx> LateLintPass<'tcx> for ImplicitSaturatingSub {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
         if expr.span.from_expansion() {
             return;
         }
+        if in_constant(cx, expr.hir_id) && !self.msrv.meets(msrvs::SATURATING_SUB_CONST) {
+            return;
+        }
         if let Some(higher::If { cond, then, r#else: None }) = higher::If::hir(expr)
 
             // Check if the conditional expression is a binary operation

clippy_lints/src/lib.rs

@@ -600,7 +600,7 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(|_| Box::new(unit_return_expecting_ord::UnitReturnExpectingOrd));
     store.register_late_pass(|_| Box::new(strings::StringAdd));
     store.register_late_pass(|_| Box::new(implicit_return::ImplicitReturn));
-    store.register_late_pass(|_| Box::new(implicit_saturating_sub::ImplicitSaturatingSub));
+    store.register_late_pass(move |_| Box::new(implicit_saturating_sub::ImplicitSaturatingSub::new(conf)));
     store.register_late_pass(|_| Box::new(default_numeric_fallback::DefaultNumericFallback));
     store.register_late_pass(|_| Box::new(inconsistent_struct_constructor::InconsistentStructConstructor));
     store.register_late_pass(|_| Box::new(non_octal_unix_permissions::NonOctalUnixPermissions));