[`ifs_same_cond`]: https://rust-lang.github.io/rust-clippy/master/index.html#ifs_same_cond
[`implicit_hasher`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_hasher
[`implicit_return`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_return
+[`implicit_saturating_sub`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_saturating_sub
[`imprecise_flops`]: https://rust-lang.github.io/rust-clippy/master/index.html#imprecise_flops
[`inconsistent_digit_grouping`]: https://rust-lang.github.io/rust-clippy/master/index.html#inconsistent_digit_grouping
[`indexing_slicing`]: https://rust-lang.github.io/rust-clippy/master/index.html#indexing_slicing
--- /dev/null
+use crate::utils::{higher, in_macro, match_qpath, span_lint_and_sugg, 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_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+ /// **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:**
+ ///
+ /// ```rust
+ /// 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);
+ /// ```
+ pub IMPLICIT_SATURATING_SUB,
+ pedantic,
+ "Perform saturating subtraction instead of implicitly checking lower bound of data type"
+}
+
+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>) {
+ if in_macro(expr.span) {
+ return;
+ }
+ if_chain! {
+ if let Some((ref cond, ref then, None)) = higher::if_block(&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;
+
+ // 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 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 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;
+
+ then {
+ // Handle symmetric conditions in the if statement
+ let (cond_var, cond_num_val) = if SpanlessEq::new(cx).eq_expr(cond_left, target) {
+ if BinOpKind::Gt == cond_op.node || BinOpKind::Ne == cond_op.node {
+ (cond_left, cond_right)
+ } else {
+ return;
+ }
+ } else if SpanlessEq::new(cx).eq_expr(cond_right, target) {
+ if BinOpKind::Lt == cond_op.node || BinOpKind::Ne == cond_op.node {
+ (cond_right, cond_left)
+ } else {
+ return;
+ }
+ } else {
+ return;
+ };
+
+ // Check if the variable in the condition statement is an integer
+ if !cx.tables.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"];
+
+ 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() {
+ } 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::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);
+ }
+ };
+ },
+ _ => (),
+ }
+ }
+ }
+ }
+}
+
+fn subtracts_one<'a>(cx: &LateContext<'_, '_>, expr: &Expr<'a>) -> Option<&'a Expr<'a>> {
+ match expr.kind {
+ ExprKind::AssignOp(ref op1, ref target, ref 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
+ }
+ }
+ },
+ ExprKind::Assign(ref target, ref value, _) => {
+ if_chain! {
+ if let ExprKind::Binary(ref op1, ref left1, ref right1) = value.kind;
+ if BinOpKind::Sub == op1.node;
+
+ if SpanlessEq::new(cx).eq_expr(left1, target);
+
+ if let ExprKind::Lit(ref lit1) = right1.kind;
+ if let LitKind::Int(1, _) = lit1.node;
+ then {
+ Some(target)
+ } else {
+ None
+ }
+ }
+ },
+ _ => None,
+ }
+}
+
+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",
+ "try",
+ format!("{} = {}.saturating_sub({});", var_name, var_name, 1.to_string()),
+ Applicability::MachineApplicable,
+ );
+}
mod if_let_some_result;
mod if_not_else;
mod implicit_return;
+mod implicit_saturating_sub;
mod indexing_slicing;
mod infinite_iter;
mod inherent_impl;
&if_let_some_result::IF_LET_SOME_RESULT,
&if_not_else::IF_NOT_ELSE,
&implicit_return::IMPLICIT_RETURN,
+ &implicit_saturating_sub::IMPLICIT_SATURATING_SUB,
&indexing_slicing::INDEXING_SLICING,
&indexing_slicing::OUT_OF_BOUNDS_INDEXING,
&infinite_iter::INFINITE_ITER,
store.register_late_pass(|| box unicode::Unicode);
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);
store.register_late_pass(|| box map_clone::MapClone);
store.register_late_pass(|| box shadow::Shadow);
LintId::of(&functions::MUST_USE_CANDIDATE),
LintId::of(&functions::TOO_MANY_LINES),
LintId::of(&if_not_else::IF_NOT_ELSE),
+ LintId::of(&implicit_saturating_sub::IMPLICIT_SATURATING_SUB),
LintId::of(&infinite_iter::MAYBE_INFINITE_ITER),
LintId::of(&items_after_statements::ITEMS_AFTER_STATEMENTS),
LintId::of(&large_stack_arrays::LARGE_STACK_ARRAYS),
deprecation: None,
module: "implicit_return",
},
+ Lint {
+ name: "implicit_saturating_sub",
+ group: "pedantic",
+ desc: "Perform saturating subtraction instead of implicitly checking lower bound of data type",
+ deprecation: None,
+ module: "implicit_saturating_sub",
+ },
Lint {
name: "imprecise_flops",
group: "nursery",
--- /dev/null
+// run-rustfix
+#![allow(unused_assignments, unused_mut, clippy::assign_op_pattern)]
+#![warn(clippy::implicit_saturating_sub)]
+
+fn main() {
+ // Tests for unsigned integers
+
+ let end_8: u8 = 10;
+ let start_8: u8 = 5;
+ let mut u_8: u8 = end_8 - start_8;
+
+ // Lint
+ u_8 = u_8.saturating_sub(1);
+
+ match end_8 {
+ 10 => {
+ // Lint
+ u_8 = u_8.saturating_sub(1);
+ },
+ 11 => u_8 += 1,
+ _ => u_8 = 0,
+ }
+
+ let end_16: u16 = 35;
+ let start_16: u16 = 40;
+
+ let mut u_16: u16 = end_16 - start_16;
+
+ // Lint
+ u_16 = u_16.saturating_sub(1);
+
+ let mut end_32: u32 = 7000;
+ let mut start_32: u32 = 7010;
+
+ let mut u_32: u32 = end_32 - start_32;
+
+ // Lint
+ u_32 = u_32.saturating_sub(1);
+
+ // No Lint
+ if u_32 > 0 {
+ u_16 += 1;
+ }
+
+ // No Lint
+ if u_32 != 0 {
+ end_32 -= 1;
+ start_32 += 1;
+ }
+
+ let mut end_64: u64 = 75001;
+ let mut start_64: u64 = 75000;
+
+ let mut u_64: u64 = end_64 - start_64;
+
+ // Lint
+ u_64 = u_64.saturating_sub(1);
+
+ // Lint
+ u_64 = u_64.saturating_sub(1);
+
+ // Lint
+ u_64 = u_64.saturating_sub(1);
+
+ // No Lint
+ if u_64 >= 1 {
+ u_64 -= 1;
+ }
+
+ // No Lint
+ if u_64 > 0 {
+ end_64 -= 1;
+ }
+
+ // Tests for usize
+ let end_usize: usize = 8054;
+ let start_usize: usize = 8050;
+
+ let mut u_usize: usize = end_usize - start_usize;
+
+ // Lint
+ u_usize = u_usize.saturating_sub(1);
+
+ // Tests for signed integers
+
+ let endi_8: i8 = 10;
+ let starti_8: i8 = 50;
+
+ let mut i_8: i8 = endi_8 - starti_8;
+
+ // Lint
+ i_8 = i_8.saturating_sub(1);
+
+ // Lint
+ i_8 = i_8.saturating_sub(1);
+
+ // Lint
+ i_8 = i_8.saturating_sub(1);
+
+ // Lint
+ i_8 = i_8.saturating_sub(1);
+
+ let endi_16: i16 = 45;
+ let starti_16: i16 = 44;
+
+ let mut i_16: i16 = endi_16 - starti_16;
+
+ // Lint
+ i_16 = i_16.saturating_sub(1);
+
+ // Lint
+ i_16 = i_16.saturating_sub(1);
+
+ // Lint
+ i_16 = i_16.saturating_sub(1);
+
+ // Lint
+ i_16 = i_16.saturating_sub(1);
+
+ let endi_32: i32 = 45;
+ let starti_32: i32 = 44;
+
+ let mut i_32: i32 = endi_32 - starti_32;
+
+ // Lint
+ i_32 = i_32.saturating_sub(1);
+
+ // Lint
+ i_32 = i_32.saturating_sub(1);
+
+ // Lint
+ i_32 = i_32.saturating_sub(1);
+
+ // Lint
+ i_32 = i_32.saturating_sub(1);
+
+ let endi_64: i64 = 45;
+ let starti_64: i64 = 44;
+
+ let mut i_64: i64 = endi_64 - starti_64;
+
+ // Lint
+ i_64 = i_64.saturating_sub(1);
+
+ // Lint
+ i_64 = i_64.saturating_sub(1);
+
+ // Lint
+ i_64 = i_64.saturating_sub(1);
+
+ // No Lint
+ if i_64 > 0 {
+ i_64 -= 1;
+ }
+
+ // No Lint
+ if i_64 != 0 {
+ i_64 -= 1;
+ }
+}
--- /dev/null
+// run-rustfix
+#![allow(unused_assignments, unused_mut, clippy::assign_op_pattern)]
+#![warn(clippy::implicit_saturating_sub)]
+
+fn main() {
+ // Tests for unsigned integers
+
+ let end_8: u8 = 10;
+ let start_8: u8 = 5;
+ let mut u_8: u8 = end_8 - start_8;
+
+ // Lint
+ if u_8 > 0 {
+ u_8 = u_8 - 1;
+ }
+
+ match end_8 {
+ 10 => {
+ // Lint
+ if u_8 > 0 {
+ u_8 -= 1;
+ }
+ },
+ 11 => u_8 += 1,
+ _ => u_8 = 0,
+ }
+
+ let end_16: u16 = 35;
+ let start_16: u16 = 40;
+
+ let mut u_16: u16 = end_16 - start_16;
+
+ // Lint
+ if u_16 > 0 {
+ u_16 -= 1;
+ }
+
+ let mut end_32: u32 = 7000;
+ let mut start_32: u32 = 7010;
+
+ let mut u_32: u32 = end_32 - start_32;
+
+ // Lint
+ if u_32 != 0 {
+ u_32 -= 1;
+ }
+
+ // No Lint
+ if u_32 > 0 {
+ u_16 += 1;
+ }
+
+ // No Lint
+ if u_32 != 0 {
+ end_32 -= 1;
+ start_32 += 1;
+ }
+
+ let mut end_64: u64 = 75001;
+ let mut start_64: u64 = 75000;
+
+ let mut u_64: u64 = end_64 - start_64;
+
+ // Lint
+ if u_64 > 0 {
+ u_64 -= 1;
+ }
+
+ // Lint
+ if 0 < u_64 {
+ u_64 -= 1;
+ }
+
+ // Lint
+ if 0 != u_64 {
+ u_64 -= 1;
+ }
+
+ // No Lint
+ if u_64 >= 1 {
+ u_64 -= 1;
+ }
+
+ // No Lint
+ if u_64 > 0 {
+ end_64 -= 1;
+ }
+
+ // Tests for usize
+ let end_usize: usize = 8054;
+ let start_usize: usize = 8050;
+
+ let mut u_usize: usize = end_usize - start_usize;
+
+ // Lint
+ if u_usize > 0 {
+ u_usize -= 1;
+ }
+
+ // Tests for signed integers
+
+ let endi_8: i8 = 10;
+ let starti_8: i8 = 50;
+
+ let mut i_8: i8 = endi_8 - starti_8;
+
+ // Lint
+ if i_8 > i8::MIN {
+ i_8 -= 1;
+ }
+
+ // Lint
+ if i_8 > i8::min_value() {
+ i_8 -= 1;
+ }
+
+ // Lint
+ if i_8 != i8::MIN {
+ i_8 -= 1;
+ }
+
+ // Lint
+ if i_8 != i8::min_value() {
+ i_8 -= 1;
+ }
+
+ let endi_16: i16 = 45;
+ let starti_16: i16 = 44;
+
+ let mut i_16: i16 = endi_16 - starti_16;
+
+ // Lint
+ if i_16 > i16::MIN {
+ i_16 -= 1;
+ }
+
+ // Lint
+ if i_16 > i16::min_value() {
+ i_16 -= 1;
+ }
+
+ // Lint
+ if i_16 != i16::MIN {
+ i_16 -= 1;
+ }
+
+ // Lint
+ if i_16 != i16::min_value() {
+ i_16 -= 1;
+ }
+
+ let endi_32: i32 = 45;
+ let starti_32: i32 = 44;
+
+ let mut i_32: i32 = endi_32 - starti_32;
+
+ // Lint
+ if i_32 > i32::MIN {
+ i_32 -= 1;
+ }
+
+ // Lint
+ if i_32 > i32::min_value() {
+ i_32 -= 1;
+ }
+
+ // Lint
+ if i_32 != i32::MIN {
+ i_32 -= 1;
+ }
+
+ // Lint
+ if i_32 != i32::min_value() {
+ i_32 -= 1;
+ }
+
+ let endi_64: i64 = 45;
+ let starti_64: i64 = 44;
+
+ let mut i_64: i64 = endi_64 - starti_64;
+
+ // Lint
+ if i64::min_value() < i_64 {
+ i_64 -= 1;
+ }
+
+ // Lint
+ if i64::MIN != i_64 {
+ i_64 -= 1;
+ }
+
+ // Lint
+ if i64::MIN < i_64 {
+ i_64 -= 1;
+ }
+
+ // No Lint
+ if i_64 > 0 {
+ i_64 -= 1;
+ }
+
+ // No Lint
+ if i_64 != 0 {
+ i_64 -= 1;
+ }
+}
--- /dev/null
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:13:5
+ |
+LL | / if u_8 > 0 {
+LL | | u_8 = u_8 - 1;
+LL | | }
+ | |_____^ help: try: `u_8 = u_8.saturating_sub(1);`
+ |
+ = note: `-D clippy::implicit-saturating-sub` implied by `-D warnings`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:20:13
+ |
+LL | / if u_8 > 0 {
+LL | | u_8 -= 1;
+LL | | }
+ | |_____________^ help: try: `u_8 = u_8.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:34:5
+ |
+LL | / if u_16 > 0 {
+LL | | u_16 -= 1;
+LL | | }
+ | |_____^ help: try: `u_16 = u_16.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:44:5
+ |
+LL | / if u_32 != 0 {
+LL | | u_32 -= 1;
+LL | | }
+ | |_____^ help: try: `u_32 = u_32.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:65:5
+ |
+LL | / if u_64 > 0 {
+LL | | u_64 -= 1;
+LL | | }
+ | |_____^ help: try: `u_64 = u_64.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:70:5
+ |
+LL | / if 0 < u_64 {
+LL | | u_64 -= 1;
+LL | | }
+ | |_____^ help: try: `u_64 = u_64.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:75:5
+ |
+LL | / if 0 != u_64 {
+LL | | u_64 -= 1;
+LL | | }
+ | |_____^ help: try: `u_64 = u_64.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:96:5
+ |
+LL | / if u_usize > 0 {
+LL | | u_usize -= 1;
+LL | | }
+ | |_____^ help: try: `u_usize = u_usize.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:108:5
+ |
+LL | / if i_8 > i8::MIN {
+LL | | i_8 -= 1;
+LL | | }
+ | |_____^ help: try: `i_8 = i_8.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:113:5
+ |
+LL | / if i_8 > i8::min_value() {
+LL | | i_8 -= 1;
+LL | | }
+ | |_____^ help: try: `i_8 = i_8.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:118:5
+ |
+LL | / if i_8 != i8::MIN {
+LL | | i_8 -= 1;
+LL | | }
+ | |_____^ help: try: `i_8 = i_8.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:123:5
+ |
+LL | / if i_8 != i8::min_value() {
+LL | | i_8 -= 1;
+LL | | }
+ | |_____^ help: try: `i_8 = i_8.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:133:5
+ |
+LL | / if i_16 > i16::MIN {
+LL | | i_16 -= 1;
+LL | | }
+ | |_____^ help: try: `i_16 = i_16.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:138:5
+ |
+LL | / if i_16 > i16::min_value() {
+LL | | i_16 -= 1;
+LL | | }
+ | |_____^ help: try: `i_16 = i_16.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:143:5
+ |
+LL | / if i_16 != i16::MIN {
+LL | | i_16 -= 1;
+LL | | }
+ | |_____^ help: try: `i_16 = i_16.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:148:5
+ |
+LL | / if i_16 != i16::min_value() {
+LL | | i_16 -= 1;
+LL | | }
+ | |_____^ help: try: `i_16 = i_16.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:158:5
+ |
+LL | / if i_32 > i32::MIN {
+LL | | i_32 -= 1;
+LL | | }
+ | |_____^ help: try: `i_32 = i_32.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:163:5
+ |
+LL | / if i_32 > i32::min_value() {
+LL | | i_32 -= 1;
+LL | | }
+ | |_____^ help: try: `i_32 = i_32.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:168:5
+ |
+LL | / if i_32 != i32::MIN {
+LL | | i_32 -= 1;
+LL | | }
+ | |_____^ help: try: `i_32 = i_32.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:173:5
+ |
+LL | / if i_32 != i32::min_value() {
+LL | | i_32 -= 1;
+LL | | }
+ | |_____^ help: try: `i_32 = i_32.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:183:5
+ |
+LL | / if i64::min_value() < i_64 {
+LL | | i_64 -= 1;
+LL | | }
+ | |_____^ help: try: `i_64 = i_64.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:188:5
+ |
+LL | / if i64::MIN != i_64 {
+LL | | i_64 -= 1;
+LL | | }
+ | |_____^ help: try: `i_64 = i_64.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+ --> $DIR/implicit_saturating_sub.rs:193:5
+ |
+LL | / if i64::MIN < i_64 {
+LL | | i_64 -= 1;
+LL | | }
+ | |_____^ help: try: `i_64 = i_64.saturating_sub(1);`
+
+error: aborting due to 23 previous errors
+
projects / rust.git / commitdiff