use rustc::lint::*;
+use rustc::{declare_lint, lint_array};
+use if_chain::if_chain;
use rustc::hir;
-use syntax::codemap;
-use utils::{snippet, span_lint_and_then};
+use rustc::hir::BindingAnnotation;
+use rustc::hir::def::Def;
+use syntax::ast;
+use crate::utils::{snippet, span_lint_and_then};
/// **What it does:** Checks for variable declarations immediately followed by a
/// conditional affectation.
/// None
/// };
/// ```
-declare_lint! {
+declare_clippy_lint! {
pub USELESS_LET_IF_SEQ,
- Warn,
+ style,
"unidiomatic `let mut` declaration followed by initialization in `if`"
}
-#[derive(Copy,Clone)]
+#[derive(Copy, Clone)]
pub struct LetIfSeq;
impl LintPass for LetIfSeq {
fn check_block(&mut self, cx: &LateContext<'a, 'tcx>, block: &'tcx hir::Block) {
let mut it = block.stmts.iter().peekable();
while let Some(stmt) = it.next() {
- if_let_chain! {[
- let Some(expr) = it.peek(),
- let hir::StmtDecl(ref decl, _) = stmt.node,
- let hir::DeclLocal(ref decl) = decl.node,
- let hir::PatKind::Binding(mode, def_id, ref name, None) = decl.pat.node,
- let hir::StmtExpr(ref if_, _) = expr.node,
- let hir::ExprIf(ref cond, ref then, ref else_) = if_.node,
- !used_in_expr(cx, def_id, cond),
- let Some(value) = check_assign(cx, def_id, then),
- !used_in_expr(cx, def_id, value),
- ], {
- let span = codemap::mk_sp(stmt.span.lo, if_.span.hi);
-
- let (default_multi_stmts, default) = if let Some(ref else_) = *else_ {
- if let hir::ExprBlock(ref else_) = else_.node {
- if let Some(default) = check_assign(cx, def_id, else_) {
- (else_.stmts.len() > 1, default)
- } else if let Some(ref default) = decl.init {
- (true, &**default)
+ 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 Some(value) = check_assign(cx, canonical_id, &*then);
+ if !used_in_expr(cx, canonical_id, 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 {
+ 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 {
+ continue;
+ }
} else {
continue;
}
+ } else if let Some(ref default) = decl.init {
+ (false, &**default)
} else {
continue;
- }
- } else if let Some(ref default) = decl.init {
- (false, &**default)
- } else {
- continue;
- };
-
- let mutability = match mode {
- hir::BindByRef(hir::MutMutable) | hir::BindByValue(hir::MutMutable) => "<mut> ",
- _ => "",
- };
-
- // FIXME: this should not suggest `mut` if we can detect that the variable is not
- // use mutably after the `if`
-
- let sug = format!(
- "let {mut}{name} = if {cond} {{{then} {value} }} else {{{else} {default} }};",
- mut=mutability,
- name=name.node,
- cond=snippet(cx, cond.span, "_"),
- then=if then.stmts.len() > 1 { " ..;" } else { "" },
- else=if default_multi_stmts { " ..;" } else { "" },
- value=snippet(cx, value.span, "<value>"),
- default=snippet(cx, default.span, "<default>"),
- );
- span_lint_and_then(cx,
- USELESS_LET_IF_SEQ,
- span,
- "`if _ { .. } else { .. }` is an expression",
- |db| {
- db.span_suggestion(span,
- "it is more idiomatic to write",
- sug);
- if !mutability.is_empty() {
- db.note("you might not need `mut` at all");
- }
- });
- }}
+ };
+
+ let mutability = match mode {
+ BindingAnnotation::RefMut | BindingAnnotation::Mutable => "<mut> ",
+ _ => "",
+ };
+
+ // FIXME: this should not suggest `mut` if we can detect that the variable is not
+ // use mutably after the `if`
+
+ let sug = format!(
+ "let {mut}{name} = if {cond} {{{then} {value} }} else {{{else} {default} }};",
+ mut=mutability,
+ name=ident.name,
+ cond=snippet(cx, cond.span, "_"),
+ then=if then.stmts.len() > 1 { " ..;" } else { "" },
+ else=if default_multi_stmts { " ..;" } else { "" },
+ value=snippet(cx, value.span, "<value>"),
+ default=snippet(cx, default.span, "<default>"),
+ );
+ span_lint_and_then(cx,
+ USELESS_LET_IF_SEQ,
+ span,
+ "`if _ { .. } else { .. }` is an expression",
+ |db| {
+ db.span_suggestion(span,
+ "it is more idiomatic to write",
+ sug);
+ if !mutability.is_empty() {
+ db.note("you might not need `mut` at all");
+ }
+ });
+ }
+ }
}
}
}
struct UsedVisitor<'a, 'tcx: 'a> {
cx: &'a LateContext<'a, 'tcx>,
- id: hir::def_id::DefId,
+ 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_let_chain! {[
- let hir::ExprPath(ref qpath) = expr.node,
- self.id == self.cx.tcx.tables().qpath_def(qpath, expr.id).def_id(),
- ], {
- self.used = true;
- return;
- }}
+ 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::All(&self.cx.tcx.map)
+ hir::intravisit::NestedVisitorMap::None
}
}
fn check_assign<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
- decl: hir::def_id::DefId,
- block: &'tcx hir::Block
+ decl: ast::NodeId,
+ block: &'tcx hir::Block,
) -> Option<&'tcx hir::Expr> {
- if_let_chain! {[
- block.expr.is_none(),
- let Some(expr) = block.stmts.iter().last(),
- let hir::StmtSemi(ref expr, _) = expr.node,
- let hir::ExprAssign(ref var, ref value) = expr.node,
- let hir::ExprPath(ref qpath) = var.node,
- decl == cx.tcx.tables().qpath_def(qpath, var.id).def_id(),
- ], {
- let mut v = UsedVisitor {
- cx: cx,
- id: decl,
- used: false,
- };
-
- for s in block.stmts.iter().take(block.stmts.len()-1) {
- hir::intravisit::walk_stmt(&mut v, s);
-
- if v.used {
- return None;
+ 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;
+ then {
+ let mut v = UsedVisitor {
+ cx,
+ id: decl,
+ used: false,
+ };
+
+ for s in block.stmts.iter().take(block.stmts.len()-1) {
+ hir::intravisit::walk_stmt(&mut v, s);
+
+ if v.used {
+ return None;
+ }
}
- }
- return Some(value);
- }}
+ return Some(value);
+ }
+ }
None
}
-fn used_in_expr<'a, 'tcx: 'a>(cx: &LateContext<'a, 'tcx>, id: hir::def_id::DefId, expr: &'tcx hir::Expr) -> bool {
+fn used_in_expr<'a, 'tcx: 'a>(cx: &LateContext<'a, 'tcx>, id: ast::NodeId, expr: &'tcx hir::Expr) -> bool {
let mut v = UsedVisitor {
- cx: cx,
- id: id,
+ cx,
+ id,
used: false,
};
hir::intravisit::walk_expr(&mut v, expr);
projects / rust.git / blobdiff