-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_lint, lint_array};
+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::source::snippet;
+use clippy_utils::{path_to_local_id, visitors::LocalUsedVisitor};
use if_chain::if_chain;
-use rustc::hir;
-use rustc::hir::BindingAnnotation;
-use rustc::hir::def::Def;
-use syntax::ast;
-use crate::utils::{snippet, span_lint_and_then};
+use rustc_errors::Applicability;
+use rustc_hir as hir;
+use rustc_hir::BindingAnnotation;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
-/// **What it does:** Checks for variable declarations immediately followed by a
-/// conditional affectation.
-///
-/// **Why is this bad?** This is not idiomatic Rust.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust,ignore
-/// let foo;
-///
-/// if bar() {
-/// foo = 42;
-/// } else {
-/// foo = 0;
-/// }
-///
-/// let mut baz = None;
-///
-/// if bar() {
-/// baz = Some(42);
-/// }
-/// ```
-///
-/// should be written
-///
-/// ```rust,ignore
-/// let foo = if bar() {
-/// 42
-/// } else {
-/// 0
-/// };
-///
-/// let baz = if bar() {
-/// Some(42)
-/// } else {
-/// None
-/// };
-/// ```
declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for variable declarations immediately followed by a
+ /// conditional affectation.
+ ///
+ /// ### Why is this bad?
+ /// This is not idiomatic Rust.
+ ///
+ /// ### Example
+ /// ```rust,ignore
+ /// let foo;
+ ///
+ /// if bar() {
+ /// foo = 42;
+ /// } else {
+ /// foo = 0;
+ /// }
+ ///
+ /// let mut baz = None;
+ ///
+ /// if bar() {
+ /// baz = Some(42);
+ /// }
+ /// ```
+ ///
+ /// should be written
+ ///
+ /// ```rust,ignore
+ /// let foo = if bar() {
+ /// 42
+ /// } else {
+ /// 0
+ /// };
+ ///
+ /// let baz = if bar() {
+ /// Some(42)
+ /// } else {
+ /// None
+ /// };
+ /// ```
pub USELESS_LET_IF_SEQ,
- style,
+ nursery,
"unidiomatic `let mut` declaration followed by initialization in `if`"
}
-#[derive(Copy, Clone)]
-pub struct LetIfSeq;
+declare_lint_pass!(LetIfSeq => [USELESS_LET_IF_SEQ]);
-impl LintPass for LetIfSeq {
- fn get_lints(&self) -> LintArray {
- lint_array!(USELESS_LET_IF_SEQ)
- }
-}
-
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LetIfSeq {
- fn check_block(&mut self, cx: &LateContext<'a, 'tcx>, block: &'tcx hir::Block) {
+impl<'tcx> LateLintPass<'tcx> for LetIfSeq {
+ fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx hir::Block<'_>) {
let mut it = block.stmts.iter().peekable();
while let Some(stmt) = it.next() {
if_chain! {
if let Some(expr) = it.peek();
- if let hir::StmtKind::Decl(ref decl, _) = stmt.node;
- if let hir::DeclKind::Local(ref decl) = decl.node;
- if let hir::PatKind::Binding(mode, canonical_id, ident, None) = decl.pat.node;
- if let hir::StmtKind::Expr(ref if_, _) = expr.node;
- if let hir::ExprKind::If(ref cond, ref then, ref else_) = if_.node;
- if !used_in_expr(cx, canonical_id, cond);
- if let hir::ExprKind::Block(ref then, _) = then.node;
+ if let hir::StmtKind::Local(local) = stmt.kind;
+ if let hir::PatKind::Binding(mode, canonical_id, ident, None) = local.pat.kind;
+ if let hir::StmtKind::Expr(if_) = expr.kind;
+ if let hir::ExprKind::If(hir::Expr { kind: hir::ExprKind::DropTemps(cond), ..}, then, else_) = if_.kind;
+ let mut used_visitor = LocalUsedVisitor::new(cx, canonical_id);
+ if !used_visitor.check_expr(cond);
+ if let hir::ExprKind::Block(then, _) = then.kind;
if let Some(value) = check_assign(cx, canonical_id, &*then);
- if !used_in_expr(cx, canonical_id, value);
+ if !used_visitor.check_expr(value);
then {
let span = stmt.span.to(if_.span);
- let (default_multi_stmts, default) = if let Some(ref else_) = *else_ {
- if let hir::ExprKind::Block(ref else_, _) = else_.node {
+ let has_interior_mutability = !cx.typeck_results().node_type(canonical_id).is_freeze(
+ cx.tcx.at(span),
+ cx.param_env,
+ );
+ if has_interior_mutability { return; }
+
+ let (default_multi_stmts, default) = if let Some(else_) = else_ {
+ if let hir::ExprKind::Block(else_, _) = else_.kind {
if let Some(default) = check_assign(cx, canonical_id, else_) {
(else_.stmts.len() > 1, default)
- } else if let Some(ref default) = decl.init {
- (true, &**default)
+ } else if let Some(default) = local.init {
+ (true, default)
} else {
continue;
}
} else {
continue;
}
- } else if let Some(ref default) = decl.init {
- (false, &**default)
+ } else if let Some(default) = local.init {
+ (false, default)
} else {
continue;
};
USELESS_LET_IF_SEQ,
span,
"`if _ { .. } else { .. }` is an expression",
- |db| {
- db.span_suggestion(span,
- "it is more idiomatic to write",
- sug);
+ |diag| {
+ diag.span_suggestion(
+ span,
+ "it is more idiomatic to write",
+ sug,
+ Applicability::HasPlaceholders,
+ );
if !mutability.is_empty() {
- db.note("you might not need `mut` at all");
+ diag.note("you might not need `mut` at all");
}
});
}
}
}
-struct UsedVisitor<'a, 'tcx: 'a> {
- cx: &'a LateContext<'a, 'tcx>,
- id: ast::NodeId,
- used: bool,
-}
-
-impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for UsedVisitor<'a, 'tcx> {
- fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
- if_chain! {
- if let hir::ExprKind::Path(ref qpath) = expr.node;
- if let Def::Local(local_id) = self.cx.tables.qpath_def(qpath, expr.hir_id);
- if self.id == local_id;
- then {
- self.used = true;
- return;
- }
- }
- hir::intravisit::walk_expr(self, expr);
- }
- fn nested_visit_map<'this>(&'this mut self) -> hir::intravisit::NestedVisitorMap<'this, 'tcx> {
- hir::intravisit::NestedVisitorMap::None
- }
-}
-
-fn check_assign<'a, 'tcx>(
- cx: &LateContext<'a, 'tcx>,
- decl: ast::NodeId,
- block: &'tcx hir::Block,
-) -> Option<&'tcx hir::Expr> {
+fn check_assign<'tcx>(
+ cx: &LateContext<'tcx>,
+ decl: hir::HirId,
+ block: &'tcx hir::Block<'_>,
+) -> Option<&'tcx hir::Expr<'tcx>> {
if_chain! {
if block.expr.is_none();
if let Some(expr) = block.stmts.iter().last();
- if let hir::StmtKind::Semi(ref expr, _) = expr.node;
- if let hir::ExprKind::Assign(ref var, ref value) = expr.node;
- if let hir::ExprKind::Path(ref qpath) = var.node;
- if let Def::Local(local_id) = cx.tables.qpath_def(qpath, var.hir_id);
- if decl == local_id;
+ if let hir::StmtKind::Semi(expr) = expr.kind;
+ if let hir::ExprKind::Assign(var, value, _) = expr.kind;
+ if path_to_local_id(var, decl);
then {
- let mut v = UsedVisitor {
- cx,
- id: decl,
- used: false,
- };
+ let mut v = LocalUsedVisitor::new(cx, decl);
- for s in block.stmts.iter().take(block.stmts.len()-1) {
- hir::intravisit::walk_stmt(&mut v, s);
-
- if v.used {
- return None;
- }
+ if block.stmts.iter().take(block.stmts.len()-1).any(|stmt| v.check_stmt(stmt)) {
+ return None;
}
return Some(value);
None
}
-
-fn used_in_expr<'a, 'tcx: 'a>(cx: &LateContext<'a, 'tcx>, id: ast::NodeId, expr: &'tcx hir::Expr) -> bool {
- let mut v = UsedVisitor {
- cx,
- id,
- used: false,
- };
- hir::intravisit::walk_expr(&mut v, expr);
- v.used
-}