-use rustc::hir;
-use rustc::lint::*;
-use rustc::ty;
-use syntax::codemap::Span;
-use utils::{in_macro, iter_input_pats, match_type, method_chain_args, snippet, span_lint_and_then};
-use utils::paths;
+// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use crate::rustc::hir;
+use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use crate::rustc::ty;
+use crate::rustc::{declare_tool_lint, lint_array};
+use crate::rustc_errors::Applicability;
+use crate::syntax::source_map::Span;
+use crate::utils::paths;
+use crate::utils::{in_macro, iter_input_pats, match_type, method_chain_args, snippet, span_lint_and_then};
+use if_chain::if_chain;
#[derive(Clone)]
pub struct Pass;
-/// **What it does:** Checks for usage of `Option.map(f)` where f is a function
+/// **What it does:** Checks for usage of `option.map(f)` where f is a function
/// or closure that returns the unit type.
///
/// **Why is this bad?** Readability, this can be written more clearly with
-/// an if statement
+/// an if let statement
///
/// **Known problems:** None.
///
declare_clippy_lint! {
pub OPTION_MAP_UNIT_FN,
complexity,
- "using `Option.map(f)`, where f is a function or closure that returns ()"
+ "using `option.map(f)`, where f is a function or closure that returns ()"
}
-/// **What it does:** Checks for usage of `Result.map(f)` where f is a function
+/// **What it does:** Checks for usage of `result.map(f)` where f is a function
/// or closure that returns the unit type.
///
/// **Why is this bad?** Readability, this can be written more clearly with
-/// an if statement
+/// an if let statement
///
/// **Known problems:** None.
///
declare_clippy_lint! {
pub RESULT_MAP_UNIT_FN,
complexity,
- "using `Result.map(f)`, where f is a function or closure that returns ()"
+ "using `result.map(f)`, where f is a function or closure that returns ()"
}
-
impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
lint_array!(OPTION_MAP_UNIT_FN, RESULT_MAP_UNIT_FN)
}
}
-fn is_unit_type(ty: ty::Ty) -> bool {
+fn is_unit_type(ty: ty::Ty<'_>) -> bool {
match ty.sty {
- ty::TyTuple(slice) => slice.is_empty(),
- ty::TyNever => true,
+ ty::Tuple(slice) => slice.is_empty(),
+ ty::Never => true,
_ => false,
}
}
-fn is_unit_function(cx: &LateContext, expr: &hir::Expr) -> bool {
+fn is_unit_function(cx: &LateContext<'_, '_>, expr: &hir::Expr) -> bool {
let ty = cx.tables.expr_ty(expr);
- if let ty::TyFnDef(id, _) = ty.sty {
- if let Some(fn_type) = cx.tcx.fn_sig(id).no_late_bound_regions() {
+ if let ty::FnDef(id, _) = ty.sty {
+ if let Some(fn_type) = cx.tcx.fn_sig(id).no_bound_vars() {
return is_unit_type(fn_type.output());
}
}
false
}
-fn is_unit_expression(cx: &LateContext, expr: &hir::Expr) -> bool {
+fn is_unit_expression(cx: &LateContext<'_, '_>, expr: &hir::Expr) -> bool {
is_unit_type(cx.tables.expr_ty(expr))
}
/// semicolons, which causes problems when generating a suggestion. Given an
/// expression that evaluates to '()' or '!', recursively remove useless braces
/// and semi-colons until is suitable for including in the suggestion template
-fn reduce_unit_expression<'a>(cx: &LateContext, expr: &'a hir::Expr) -> Option<Span> {
+fn reduce_unit_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a hir::Expr) -> Option<Span> {
if !is_unit_expression(cx, expr) {
return None;
}
match expr.node {
- hir::ExprCall(_, _) |
- hir::ExprMethodCall(_, _, _) => {
+ hir::ExprKind::Call(_, _) | hir::ExprKind::MethodCall(_, _, _) => {
// Calls can't be reduced any more
Some(expr.span)
},
- hir::ExprBlock(ref block) => {
+ hir::ExprKind::Block(ref block, _) => {
match (&block.stmts[..], block.expr.as_ref()) {
(&[], Some(inner_expr)) => {
// If block only contains an expression,
// If block only contains statements,
// reduce `{ X; }` to `X` or `X;`
match inner_stmt.node {
- hir::StmtDecl(ref d, _) => Some(d.span),
- hir::StmtExpr(ref e, _) => Some(e.span),
- hir::StmtSemi(_, _) => Some(inner_stmt.span),
+ hir::StmtKind::Decl(ref d, _) => Some(d.span),
+ hir::StmtKind::Expr(ref e, _) => Some(e.span),
+ hir::StmtKind::Semi(_, _) => Some(inner_stmt.span),
}
},
_ => {
//
// We do not attempt to build a suggestion for those right now.
None
- }
+ },
}
},
_ => None,
}
fn unit_closure<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'a hir::Expr) -> Option<(&'tcx hir::Arg, &'a hir::Expr)> {
- if let hir::ExprClosure(_, ref decl, inner_expr_id, _, _) = expr.node {
+ if let hir::ExprKind::Closure(_, ref decl, inner_expr_id, _, _) = expr.node {
let body = cx.tcx.hir.body(inner_expr_id);
let body_expr = &body.value;
None
}
-/// Builds a name for the let binding variable (var_arg)
+/// Builds a name for the let binding variable (`var_arg`)
///
/// `x.field` => `x_field`
/// `y` => `_y`
///
/// Anything else will return `_`.
-fn let_binding_name(cx: &LateContext, var_arg: &hir::Expr) -> String {
+fn let_binding_name(cx: &LateContext<'_, '_>, var_arg: &hir::Expr) -> String {
match &var_arg.node {
- hir::ExprField(_, _) => snippet(cx, var_arg.span, "_").replace(".", "_"),
- hir::ExprPath(_) => format!("_{}", snippet(cx, var_arg.span, "")),
- _ => "_".to_string()
+ hir::ExprKind::Field(_, _) => snippet(cx, var_arg.span, "_").replace(".", "_"),
+ hir::ExprKind::Path(_) => format!("_{}", snippet(cx, var_arg.span, "")),
+ _ => "_".to_string(),
}
}
fn suggestion_msg(function_type: &str, map_type: &str) -> String {
format!(
"called `map(f)` on an {0} value where `f` is a unit {1}",
- map_type,
- function_type
+ map_type, function_type
)
}
-fn lint_map_unit_fn(cx: &LateContext, stmt: &hir::Stmt, expr: &hir::Expr, map_args: &[hir::Expr]) {
+fn lint_map_unit_fn(cx: &LateContext<'_, '_>, stmt: &hir::Stmt, expr: &hir::Expr, map_args: &[hir::Expr]) {
let var_arg = &map_args[0];
let fn_arg = &map_args[1];
- let (map_type, variant, lint) =
- if match_type(cx, cx.tables.expr_ty(var_arg), &paths::OPTION) {
- ("Option", "Some", OPTION_MAP_UNIT_FN)
- } else if match_type(cx, cx.tables.expr_ty(var_arg), &paths::RESULT) {
- ("Result", "Ok", RESULT_MAP_UNIT_FN)
- } else {
- return
- };
+ let (map_type, variant, lint) = if match_type(cx, cx.tables.expr_ty(var_arg), &paths::OPTION) {
+ ("Option", "Some", OPTION_MAP_UNIT_FN)
+ } else if match_type(cx, cx.tables.expr_ty(var_arg), &paths::RESULT) {
+ ("Result", "Ok", RESULT_MAP_UNIT_FN)
+ } else {
+ return;
+ };
if is_unit_function(cx, fn_arg) {
let msg = suggestion_msg("function", map_type);
- let suggestion = format!("if let {0}({1}) = {2} {{ {3}(...) }}",
- variant,
- let_binding_name(cx, var_arg),
- snippet(cx, var_arg.span, "_"),
- snippet(cx, fn_arg.span, "_"));
+ let suggestion = format!(
+ "if let {0}({1}) = {2} {{ {3}(...) }}",
+ variant,
+ let_binding_name(cx, var_arg),
+ snippet(cx, var_arg.span, "_"),
+ snippet(cx, fn_arg.span, "_")
+ );
span_lint_and_then(cx, lint, expr.span, &msg, |db| {
- db.span_approximate_suggestion(stmt.span, "try this", suggestion);
+ db.span_suggestion_with_applicability(stmt.span, "try this", suggestion, Applicability::Unspecified);
});
} else if let Some((binding, closure_expr)) = unit_closure(cx, fn_arg) {
let msg = suggestion_msg("closure", map_type);
- enum Suggestion {
- Full(String),
- Approx(String)
- }
-
- let suggestion = if let Some(expr_span) = reduce_unit_expression(cx, closure_expr) {
- Suggestion::Full(
- format!("if let {0}({1}) = {2} {{ {3} }}",
- variant,
- snippet(cx, binding.pat.span, "_"),
- snippet(cx, var_arg.span, "_"),
- snippet(cx, expr_span, "_"))
- )
- } else {
- Suggestion::Approx(
- format!("if let {0}({1}) = {2} {{ ... }}",
- variant,
- snippet(cx, binding.pat.span, "_"),
- snippet(cx, var_arg.span, "_"))
- )
- };
-
span_lint_and_then(cx, lint, expr.span, &msg, |db| {
- match suggestion {
- Suggestion::Full(sugg) => db.span_suggestion(stmt.span, "try this", sugg),
- Suggestion::Approx(sugg) => db.span_approximate_suggestion(stmt.span, "try this", sugg),
- };
+ if let Some(reduced_expr_span) = reduce_unit_expression(cx, closure_expr) {
+ let suggestion = format!(
+ "if let {0}({1}) = {2} {{ {3} }}",
+ variant,
+ snippet(cx, binding.pat.span, "_"),
+ snippet(cx, var_arg.span, "_"),
+ snippet(cx, reduced_expr_span, "_")
+ );
+ db.span_suggestion_with_applicability(
+ stmt.span,
+ "try this",
+ suggestion,
+ Applicability::MachineApplicable, // snippet
+ );
+ } else {
+ let suggestion = format!(
+ "if let {0}({1}) = {2} {{ ... }}",
+ variant,
+ snippet(cx, binding.pat.span, "_"),
+ snippet(cx, var_arg.span, "_")
+ );
+ db.span_suggestion_with_applicability(stmt.span, "try this", suggestion, Applicability::Unspecified);
+ }
});
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
- fn check_stmt(&mut self, cx: &LateContext, stmt: &hir::Stmt) {
+ fn check_stmt(&mut self, cx: &LateContext<'_, '_>, stmt: &hir::Stmt) {
if in_macro(stmt.span) {
return;
}
- if let hir::StmtSemi(ref expr, _) = stmt.node {
- if let hir::ExprMethodCall(_, _, _) = expr.node {
- if let Some(arglists) = method_chain_args(expr, &["map"]) {
- lint_map_unit_fn(cx, stmt, expr, arglists[0]);
- }
+ if let hir::StmtKind::Semi(ref expr, _) = stmt.node {
+ if let Some(arglists) = method_chain_args(expr, &["map"]) {
+ lint_map_unit_fn(cx, stmt, expr, arglists[0]);
}
}
}
projects / rust.git / blobdiff