-use crate::utils::paths;
-use crate::utils::{iter_input_pats, match_type, method_chain_args, snippet, span_lint_and_then};
+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::source::snippet;
+use clippy_utils::ty::is_type_diagnostic_item;
+use clippy_utils::{iter_input_pats, method_chain_args};
use if_chain::if_chain;
-use rustc::ty::{self, Ty};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::{self, Ty};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
+use rustc_span::sym;
declare_clippy_lint! {
/// **What it does:** Checks for usage of `option.map(f)` where f is a function
- /// or closure that returns the unit type.
+ /// or closure that returns the unit type `()`.
///
/// **Why is this bad?** Readability, this can be written more clearly with
/// an if let statement
declare_clippy_lint! {
/// **What it does:** Checks for usage of `result.map(f)` where f is a function
- /// or closure that returns the unit type.
+ /// or closure that returns the unit type `()`.
///
/// **Why is this bad?** Readability, this can be written more clearly with
/// an if let statement
declare_lint_pass!(MapUnit => [OPTION_MAP_UNIT_FN, RESULT_MAP_UNIT_FN]);
fn is_unit_type(ty: Ty<'_>) -> bool {
- match ty.kind {
+ match ty.kind() {
ty::Tuple(slice) => slice.is_empty(),
ty::Never => true,
_ => false,
}
}
-fn is_unit_function(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>) -> bool {
- let ty = cx.tables.expr_ty(expr);
+fn is_unit_function(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
+ let ty = cx.typeck_results().expr_ty(expr);
- if let ty::FnDef(id, _) = ty.kind {
+ if let ty::FnDef(id, _) = *ty.kind() {
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 {
- is_unit_type(cx.tables.expr_ty(expr))
+fn is_unit_expression(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
+ is_unit_type(cx.typeck_results().expr_ty(expr))
}
/// The expression inside a closure may or may not have surrounding braces and
/// 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.kind {
- hir::ExprKind::Call(_, _) | hir::ExprKind::MethodCall(_, _, _) => {
+ hir::ExprKind::Call(_, _) | hir::ExprKind::MethodCall(_, _, _, _) => {
// Calls can't be reduced any more
Some(expr.span)
},
- hir::ExprKind::Block(ref block, _) => {
- match (&block.stmts[..], block.expr.as_ref()) {
+ hir::ExprKind::Block(block, _) => {
+ match (block.stmts, block.expr.as_ref()) {
(&[], Some(inner_expr)) => {
// If block only contains an expression,
// reduce `{ X }` to `X`
// If block only contains statements,
// reduce `{ X; }` to `X` or `X;`
match inner_stmt.kind {
- hir::StmtKind::Local(ref local) => Some(local.span),
- hir::StmtKind::Expr(ref e) => Some(e.span),
+ hir::StmtKind::Local(local) => Some(local.span),
+ hir::StmtKind::Expr(e) => Some(e.span),
hir::StmtKind::Semi(..) => Some(inner_stmt.span),
hir::StmtKind::Item(..) => None,
}
}
}
-fn unit_closure<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
- expr: &'a hir::Expr<'a>,
-) -> Option<(&'tcx hir::Param<'tcx>, &'a hir::Expr<'a>)> {
- if let hir::ExprKind::Closure(_, ref decl, inner_expr_id, _, _) = expr.kind {
+fn unit_closure<'tcx>(
+ cx: &LateContext<'tcx>,
+ expr: &hir::Expr<'_>,
+) -> Option<(&'tcx hir::Param<'tcx>, &'tcx hir::Expr<'tcx>)> {
+ if_chain! {
+ if let hir::ExprKind::Closure(_, decl, inner_expr_id, _, _) = expr.kind;
let body = cx.tcx.hir().body(inner_expr_id);
let body_expr = &body.value;
-
- if_chain! {
- if decl.inputs.len() == 1;
- if is_unit_expression(cx, body_expr);
- if let Some(binding) = iter_input_pats(&decl, body).next();
- then {
- return Some((binding, body_expr));
- }
+ if decl.inputs.len() == 1;
+ if is_unit_expression(cx, body_expr);
+ if let Some(binding) = iter_input_pats(decl, body).next();
+ then {
+ return Some((binding, body_expr));
}
}
None
/// `x.field` => `x_field`
/// `y` => `_y`
///
-/// Anything else will return `_`.
-fn let_binding_name(cx: &LateContext<'_, '_>, var_arg: &hir::Expr<'_>) -> String {
+/// Anything else will return `a`.
+fn let_binding_name(cx: &LateContext<'_>, var_arg: &hir::Expr<'_>) -> String {
match &var_arg.kind {
hir::ExprKind::Field(_, _) => snippet(cx, var_arg.span, "_").replace(".", "_"),
hir::ExprKind::Path(_) => format!("_{}", snippet(cx, var_arg.span, "")),
- _ => "_".to_string(),
+ _ => "a".to_string(),
}
}
#[must_use]
fn suggestion_msg(function_type: &str, map_type: &str) -> String {
format!(
- "called `map(f)` on an `{0}` value where `f` is a {1} that returns the unit type",
+ "called `map(f)` on an `{0}` value where `f` is a {1} that returns the unit 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 (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 is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(var_arg), sym::option_type) {
+ ("Option", "Some", OPTION_MAP_UNIT_FN)
+ } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(var_arg), sym::result_type) {
+ ("Result", "Ok", RESULT_MAP_UNIT_FN)
+ } else {
+ return;
+ };
let fn_arg = &map_args[1];
if is_unit_function(cx, fn_arg) {
binding = let_binding_name(cx, var_arg)
);
- span_lint_and_then(cx, lint, expr.span, &msg, |db| {
- db.span_suggestion(stmt.span, "try this", suggestion, Applicability::MachineApplicable);
+ span_lint_and_then(cx, lint, expr.span, &msg, |diag| {
+ diag.span_suggestion(stmt.span, "try this", suggestion, Applicability::MachineApplicable);
});
} else if let Some((binding, closure_expr)) = unit_closure(cx, fn_arg) {
let msg = suggestion_msg("closure", map_type);
- span_lint_and_then(cx, lint, expr.span, &msg, |db| {
+ span_lint_and_then(cx, lint, expr.span, &msg, |diag| {
if let Some(reduced_expr_span) = reduce_unit_expression(cx, closure_expr) {
let suggestion = format!(
"if let {0}({1}) = {2} {{ {3} }}",
snippet(cx, var_arg.span, "_"),
snippet(cx, reduced_expr_span, "_")
);
- db.span_suggestion(
+ diag.span_suggestion(
stmt.span,
"try this",
suggestion,
snippet(cx, binding.pat.span, "_"),
snippet(cx, var_arg.span, "_"),
);
- db.span_suggestion(stmt.span, "try this", suggestion, Applicability::HasPlaceholders);
+ diag.span_suggestion(stmt.span, "try this", suggestion, Applicability::HasPlaceholders);
}
});
}
}
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MapUnit {
- fn check_stmt(&mut self, cx: &LateContext<'_, '_>, stmt: &hir::Stmt<'_>) {
+impl<'tcx> LateLintPass<'tcx> for MapUnit {
+ fn check_stmt(&mut self, cx: &LateContext<'_>, stmt: &hir::Stmt<'_>) {
if stmt.span.from_expansion() {
return;
}
- if let hir::StmtKind::Semi(ref expr) = stmt.kind {
+ if let hir::StmtKind::Semi(expr) = stmt.kind {
if let Some(arglists) = method_chain_args(expr, &["map"]) {
lint_map_unit_fn(cx, stmt, expr, arglists[0]);
}
projects / rust.git / blobdiff