-use crate::utils::{higher, in_macro, match_qpath, span_lint_and_sugg, SpanlessEq};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::higher;
+use clippy_utils::{in_macro, SpanlessEq};
use if_chain::if_chain;
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, Expr, ExprKind, QPath, StmtKind};
+use rustc_hir::{lang_items::LangItem, BinOpKind, Expr, ExprKind, QPath, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
- /// **What it does:** Checks for implicit saturating subtraction.
+ /// ### What it does
+ /// Checks for implicit saturating subtraction.
///
- /// **Why is this bad?** Simplicity and readability. Instead we can easily use an builtin function.
- ///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Why is this bad?
+ /// Simplicity and readability. Instead we can easily use an builtin function.
///
+ /// ### Example
/// ```rust
/// let end: u32 = 10;
/// let start: u32 = 5;
/// 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);
declare_lint_pass!(ImplicitSaturatingSub => [IMPLICIT_SATURATING_SUB]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImplicitSaturatingSub {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'tcx>) {
+impl<'tcx> LateLintPass<'tcx> for ImplicitSaturatingSub {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
if in_macro(expr.span) {
return;
}
if_chain! {
- if let Some((ref cond, ref then, None)) = higher::if_block(&expr);
+ if let Some(higher::If { cond, then, .. }) = higher::If::hir(expr);
// Check if the conditional expression is a binary operation
- if let ExprKind::Binary(ref cond_op, ref cond_left, ref cond_right) = cond.kind;
+ if let ExprKind::Binary(ref cond_op, cond_left, cond_right) = cond.kind;
// Ensure that the binary operator is >, != and <
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(ref block, _) = then.kind;
+ 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(ref e) = block.stmts[0].kind;
+ if let StmtKind::Semi(e) = block.stmts[0].kind;
if let Some(target) = subtracts_one(cx, e);
// Extracting out the variable name
- if let ExprKind::Path(ref assign_path) = target.kind;
- if let QPath::Resolved(_, ref ares_path) = assign_path;
+ if let ExprKind::Path(QPath::Resolved(_, ares_path)) = target.kind;
then {
// Handle symmetric conditions in the if statement
};
// Check if the variable in the condition statement is an integer
- if !cx.tables.expr_ty(cond_var).is_integral() {
+ if !cx.typeck_results().expr_ty(cond_var).is_integral() {
return;
}
// Get the variable name
let var_name = ares_path.segments[0].ident.name.as_str();
- const INT_TYPES: [&str; 5] = ["i8", "i16", "i32", "i64", "i128"];
+ 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.tables.expr_ty(cond_left).is_signed() {
+ if cx.typeck_results().expr_ty(cond_left).is_signed() {
} else {
print_lint_and_sugg(cx, &var_name, expr);
};
}
},
- ExprKind::Path(ref cond_num_path) => {
- if INT_TYPES.iter().any(|int_type| match_qpath(cond_num_path, &[int_type, "MIN"])) {
- print_lint_and_sugg(cx, &var_name, expr);
- };
+ ExprKind::Path(QPath::TypeRelative(_, name)) => {
+ if_chain! {
+ 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);
+ then {
+ print_lint_and_sugg(cx, &var_name, expr)
+ }
+ }
},
- ExprKind::Call(ref func, _) => {
- if let ExprKind::Path(ref cond_num_path) = func.kind {
- if INT_TYPES.iter().any(|int_type| match_qpath(cond_num_path, &[int_type, "min_value"])) {
- print_lint_and_sugg(cx, &var_name, expr);
+ ExprKind::Call(func, []) => {
+ if_chain! {
+ if let ExprKind::Path(QPath::TypeRelative(_, name)) = func.kind;
+ 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);
+ then {
+ print_lint_and_sugg(cx, &var_name, expr)
}
- };
+ }
},
_ => (),
}
}
}
-fn subtracts_one<'a>(cx: &LateContext<'_, '_>, expr: &Expr<'a>) -> Option<&'a Expr<'a>> {
+fn subtracts_one<'a>(cx: &LateContext<'_>, expr: &Expr<'a>) -> Option<&'a Expr<'a>> {
match expr.kind {
- ExprKind::AssignOp(ref op1, ref target, ref value) => {
+ ExprKind::AssignOp(ref op1, target, value) => {
if_chain! {
if BinOpKind::Sub == op1.node;
// Check if literal being subtracted is one
}
}
},
- ExprKind::Assign(ref target, ref value, _) => {
+ ExprKind::Assign(target, value, _) => {
if_chain! {
- if let ExprKind::Binary(ref op1, ref left1, ref right1) = value.kind;
+ if let ExprKind::Binary(ref op1, left1, right1) = value.kind;
if BinOpKind::Sub == op1.node;
if SpanlessEq::new(cx).eq_expr(left1, target);
}
}
-fn print_lint_and_sugg(cx: &LateContext<'_, '_>, var_name: &str, expr: &Expr<'_>) {
+fn print_lint_and_sugg(cx: &LateContext<'_>, var_name: &str, expr: &Expr<'_>) {
span_lint_and_sugg(
cx,
IMPLICIT_SATURATING_SUB,
expr.span,
- "Implicitly performing saturating subtraction",
+ "implicitly performing saturating subtraction",
"try",
- format!("{} = {}.saturating_sub({});", var_name, var_name, 1.to_string()),
+ format!("{} = {}.saturating_sub({});", var_name, var_name, '1'),
Applicability::MachineApplicable,
);
}