use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::higher;
-use clippy_utils::SpanlessEq;
+use clippy_utils::{higher, is_integer_literal, peel_blocks_with_stmt, SpanlessEq};
use if_chain::if_chain;
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
-use rustc_hir::{lang_items::LangItem, BinOpKind, Expr, ExprKind, QPath, StmtKind};
+use rustc_hir::{BinOpKind, Expr, ExprKind, QPath};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
///
/// ### Example
/// ```rust
- /// let end: u32 = 10;
- /// let start: u32 = 5;
- ///
+ /// # let end: u32 = 10;
+ /// # let start: u32 = 5;
/// let mut i: u32 = end - start;
///
- /// // Bad
/// if i != 0 {
/// i -= 1;
/// }
+ /// ```
+ ///
+ /// Use instead:
+ /// ```rust
+ /// # let end: u32 = 10;
+ /// # let start: u32 = 5;
+ /// let mut i: u32 = end - start;
///
- /// // Good
/// i = i.saturating_sub(1);
/// ```
#[clippy::version = "1.44.0"]
pub IMPLICIT_SATURATING_SUB,
- pedantic,
+ style,
"Perform saturating subtraction instead of implicitly checking lower bound of data type"
}
// Check if the conditional expression is a binary operation
if let ExprKind::Binary(ref cond_op, cond_left, cond_right) = cond.kind;
- // Ensure that the binary operator is >, != and <
+ // Ensure that the binary operator is >, !=, or <
if BinOpKind::Ne == cond_op.node || BinOpKind::Gt == cond_op.node || BinOpKind::Lt == cond_op.node;
- // Check if the true condition block has only one statement
- if let ExprKind::Block(block, _) = then.kind;
- if block.stmts.len() == 1 && block.expr.is_none();
-
// Check if assign operation is done
- if let StmtKind::Semi(e) = block.stmts[0].kind;
- if let Some(target) = subtracts_one(cx, e);
+ if let Some(target) = subtracts_one(cx, then);
// Extracting out the variable name
if let ExprKind::Path(QPath::Resolved(_, ares_path)) = target.kind;
// Get the variable name
let var_name = ares_path.segments[0].ident.name.as_str();
- const INT_TYPES: [LangItem; 5] = [
- LangItem::I8,
- LangItem::I16,
- LangItem::I32,
- LangItem::I64,
- LangItem::Isize
- ];
-
match cond_num_val.kind {
ExprKind::Lit(ref cond_lit) => {
// Check if the constant is zero
if let LitKind::Int(0, _) = cond_lit.node {
if cx.typeck_results().expr_ty(cond_left).is_signed() {
} else {
- print_lint_and_sugg(cx, &var_name, expr);
+ print_lint_and_sugg(cx, var_name, expr);
};
}
},
if name.ident.as_str() == "MIN";
if let Some(const_id) = cx.typeck_results().type_dependent_def_id(cond_num_val.hir_id);
if let Some(impl_id) = cx.tcx.impl_of_method(const_id);
- let mut int_ids = INT_TYPES.iter().filter_map(|&ty| cx.tcx.lang_items().require(ty).ok());
- if int_ids.any(|int_id| int_id == impl_id);
+ if let None = cx.tcx.impl_trait_ref(impl_id); // An inherent impl
+ if cx.tcx.type_of(impl_id).is_integral();
then {
- print_lint_and_sugg(cx, &var_name, expr)
+ print_lint_and_sugg(cx, var_name, expr)
}
}
},
if name.ident.as_str() == "min_value";
if let Some(func_id) = cx.typeck_results().type_dependent_def_id(func.hir_id);
if let Some(impl_id) = cx.tcx.impl_of_method(func_id);
- let mut int_ids = INT_TYPES.iter().filter_map(|&ty| cx.tcx.lang_items().require(ty).ok());
- if int_ids.any(|int_id| int_id == impl_id);
+ if let None = cx.tcx.impl_trait_ref(impl_id); // An inherent impl
+ if cx.tcx.type_of(impl_id).is_integral();
then {
- print_lint_and_sugg(cx, &var_name, expr)
+ print_lint_and_sugg(cx, var_name, expr)
}
}
},
}
}
-fn subtracts_one<'a>(cx: &LateContext<'_>, expr: &Expr<'a>) -> Option<&'a Expr<'a>> {
- match expr.kind {
+fn subtracts_one<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<&'a Expr<'a>> {
+ match peel_blocks_with_stmt(expr).kind {
ExprKind::AssignOp(ref op1, target, value) => {
- if_chain! {
- if BinOpKind::Sub == op1.node;
- // Check if literal being subtracted is one
- if let ExprKind::Lit(ref lit1) = value.kind;
- if let LitKind::Int(1, _) = lit1.node;
- then {
- Some(target)
- } else {
- None
- }
- }
+ // Check if literal being subtracted is one
+ (BinOpKind::Sub == op1.node && is_integer_literal(value, 1)).then_some(target)
},
ExprKind::Assign(target, value, _) => {
if_chain! {
if SpanlessEq::new(cx).eq_expr(left1, target);
- if let ExprKind::Lit(ref lit1) = right1.kind;
- if let LitKind::Int(1, _) = lit1.node;
+ if is_integer_literal(right1, 1);
then {
Some(target)
} else {
expr.span,
"implicitly performing saturating subtraction",
"try",
- format!("{} = {}.saturating_sub({});", var_name, var_name, '1'),
+ format!("{var_name} = {var_name}.saturating_sub({});", '1'),
Applicability::MachineApplicable,
);
}