Add the from_str_radix_10 lint

CHANGELOG.md

@@ -2092,6 +2092,7 @@ Released 2018-09-13
 [`forget_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#forget_ref
 [`from_iter_instead_of_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#from_iter_instead_of_collect
 [`from_over_into`]: https://rust-lang.github.io/rust-clippy/master/index.html#from_over_into
+[`from_str_radix_10`]: https://rust-lang.github.io/rust-clippy/master/index.html#from_str_radix_10
 [`future_not_send`]: https://rust-lang.github.io/rust-clippy/master/index.html#future_not_send
 [`get_last_with_len`]: https://rust-lang.github.io/rust-clippy/master/index.html#get_last_with_len
 [`get_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap

clippy_lints/src/from_str_radix_10.rs

@@ -0,0 +1,74 @@
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::*;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+use crate::utils::span_lint_and_sugg;
+
+declare_clippy_lint! {
+    /// **What it does:**
+    /// Checks for function invocations of the form `primitive::from_str_radix(s, 10)`
+    ///
+    /// **Why is this bad?**
+    /// This specific common use case can be rewritten as `s.parse::<primitive>()`
+    /// (and in most cases, the turbofish can be removed), which reduces code length
+    /// and complexity.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```ignore
+    /// let input: &str = get_input();
+    /// let num = u16::from_str_radix(input, 10)?;
+    /// ```
+    /// Use instead:
+    /// ```ignore
+    /// let input: &str = get_input();
+    /// let num: u16 = input.parse()?;
+    /// ```
+    pub FROM_STR_RADIX_10,
+    style,
+    "from_str_radix with radix 10"
+}
+
+declare_lint_pass!(FromStrRadix10 => [FROM_STR_RADIX_10]);
+
+impl LateLintPass<'tcx> for FromStrRadix10 {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, exp: &Expr<'tcx>) {
+        if_chain! {
+            if let ExprKind::Call(maybe_path, arguments) = &exp.kind;
+            if let ExprKind::Path(qpath) = &maybe_path.kind;
+            if let QPath::TypeRelative(ty, pathseg) = &qpath;
+
+            // check if the first part of the path is some integer primitive
+            if let TyKind::Path(ty_qpath) = &ty.kind;
+            let ty_res = cx.qpath_res(ty_qpath, ty.hir_id);
+            if let def::Res::PrimTy(prim_ty) = ty_res;
+            if matches!(prim_ty, PrimTy::Int(_) | PrimTy::Uint(_));
+
+            // check if the second part of the path indeed calls the associated
+            // function `from_str_radix`
+            if pathseg.ident.name.as_str() == "from_str_radix";
+
+            // check if the second argument is a primitive `10`
+            if arguments.len() == 2;
+            if let ExprKind::Lit(lit) = &arguments[1].kind;
+            if let rustc_ast::ast::LitKind::Int(10, _) = lit.node;
+
+            then {
+                let orig_string = crate::utils::snippet(cx, arguments[0].span, "string");
+                span_lint_and_sugg(
+                    cx,
+                    FROM_STR_RADIX_10,
+                    exp.span,
+                    "this call to `from_str_radix` can be replaced with a call to `str::parse`",
+                    "try",
+                    format!("({}).parse()", orig_string),
+                    Applicability::MaybeIncorrect
+                );
+            }
+        }
+    }
+}

clippy_lints/src/lib.rs

@@ -210,6 +210,7 @@ mod floating_point_arithmetic;
 mod format;
 mod formatting;
 mod from_over_into;
+mod from_str_radix_10;
 mod functions;
 mod future_not_send;
 mod get_last_with_len;
@@ -637,6 +638,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &formatting::SUSPICIOUS_ELSE_FORMATTING,
         &formatting::SUSPICIOUS_UNARY_OP_FORMATTING,
         &from_over_into::FROM_OVER_INTO,
+        &from_str_radix_10::FROM_STR_RADIX_10,
         &functions::DOUBLE_MUST_USE,
         &functions::MUST_USE_CANDIDATE,
         &functions::MUST_USE_UNIT,
@@ -1256,6 +1258,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(move || box types::PtrAsPtr::new(msrv));
     store.register_late_pass(|| box case_sensitive_file_extension_comparisons::CaseSensitiveFileExtensionComparisons);
     store.register_late_pass(|| box redundant_slicing::RedundantSlicing);
+    store.register_late_pass(|| box from_str_radix_10::FromStrRadix10);
 
     store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
         LintId::of(&arithmetic::FLOAT_ARITHMETIC),
@@ -1468,6 +1471,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&formatting::SUSPICIOUS_ELSE_FORMATTING),
         LintId::of(&formatting::SUSPICIOUS_UNARY_OP_FORMATTING),
         LintId::of(&from_over_into::FROM_OVER_INTO),
+        LintId::of(&from_str_radix_10::FROM_STR_RADIX_10),
         LintId::of(&functions::DOUBLE_MUST_USE),
         LintId::of(&functions::MUST_USE_UNIT),
         LintId::of(&functions::NOT_UNSAFE_PTR_ARG_DEREF),
@@ -1724,6 +1728,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&formatting::SUSPICIOUS_ELSE_FORMATTING),
         LintId::of(&formatting::SUSPICIOUS_UNARY_OP_FORMATTING),
         LintId::of(&from_over_into::FROM_OVER_INTO),
+        LintId::of(&from_str_radix_10::FROM_STR_RADIX_10),
         LintId::of(&functions::DOUBLE_MUST_USE),
         LintId::of(&functions::MUST_USE_UNIT),
         LintId::of(&functions::RESULT_UNIT_ERR),

tests/ui/from_str_radix_10.rs

@@ -0,0 +1,36 @@
+#![warn(clippy::from_str_radix_10)]
+
+mod some_mod {
+    // fake function that shouldn't trigger the lint
+    pub fn from_str_radix(_: &str, _: u32) -> Result<(), std::num::ParseIntError> {
+        unimplemented!()
+    }
+}
+
+// fake function that shouldn't trigger the lint
+fn from_str_radix(_: &str, _: u32) -> Result<(), std::num::ParseIntError> {
+    unimplemented!()
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    // all of these should trigger the lint
+    u32::from_str_radix("30", 10)?;
+    i64::from_str_radix("24", 10)?;
+    isize::from_str_radix("100", 10)?;
+    u8::from_str_radix("7", 10)?;
+
+    let string = "300";
+    i32::from_str_radix(string, 10)?;
+
+    // none of these should trigger the lint
+    u16::from_str_radix("20", 3)?;
+    i32::from_str_radix("45", 12)?;
+    usize::from_str_radix("10", 16)?;
+    i128::from_str_radix("10", 13)?;
+    some_mod::from_str_radix("50", 10)?;
+    some_mod::from_str_radix("50", 6)?;
+    from_str_radix("50", 10)?;
+    from_str_radix("50", 6)?;
+
+    Ok(())
+}

tests/ui/from_str_radix_10.stderr

@@ -0,0 +1,34 @@
+error: this call to `from_str_radix` can be replaced with a call to `str::parse`
+  --> $DIR/from_str_radix_10.rs:17:5
+   |
+LL |     u32::from_str_radix("30", 10)?;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `("30").parse()`
+   |
+   = note: `-D clippy::from-str-radix-10` implied by `-D warnings`
+
+error: this call to `from_str_radix` can be replaced with a call to `str::parse`
+  --> $DIR/from_str_radix_10.rs:18:5
+   |
+LL |     i64::from_str_radix("24", 10)?;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `("24").parse()`
+
+error: this call to `from_str_radix` can be replaced with a call to `str::parse`
+  --> $DIR/from_str_radix_10.rs:19:5
+   |
+LL |     isize::from_str_radix("100", 10)?;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `("100").parse()`
+
+error: this call to `from_str_radix` can be replaced with a call to `str::parse`
+  --> $DIR/from_str_radix_10.rs:20:5
+   |
+LL |     u8::from_str_radix("7", 10)?;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `("7").parse()`
+
+error: this call to `from_str_radix` can be replaced with a call to `str::parse`
+  --> $DIR/from_str_radix_10.rs:23:5
+   |
+LL |     i32::from_str_radix(string, 10)?;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(string).parse()`
+
+error: aborting due to 5 previous errors
+