mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-11-23 05:03:21 +00:00
fix never_loop
This commit is contained in:
Cameron Steffen
parent
533a50547f
commit
9ccb7108b5
2 changed files with 90 additions and 34 deletions
|
|
@ -16,6 +16,7 @@ use rustc::ty::{self, Ty};
|
|||
use rustc::ty::subst::{Subst, Substs};
|
||||
use rustc_const_eval::ConstContext;
|
||||
use std::collections::{HashMap, HashSet};
|
||||
use std::iter::{Iterator, once};
|
||||
use syntax::ast;
|
||||
use syntax::codemap::Span;
|
||||
use utils::sugg;
|
||||
|
|
@ -378,7 +379,12 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
|
|||
match expr.node {
|
||||
ExprWhile(_, ref block, _) |
|
||||
ExprLoop(ref block, _, _) => {
|
||||
if never_loop(block, expr.id) {
|
||||
let mut state = NeverLoopState {
|
||||
breaks: HashSet::new(),
|
||||
continues: HashSet::new(),
|
||||
};
|
||||
let may_complete = never_loop_block(block, &mut state);
|
||||
if !may_complete && !state.continues.contains(&expr.id) {
|
||||
span_lint(cx, NEVER_LOOP, expr.span, "this loop never actually loops");
|
||||
}
|
||||
},
|
||||
|
|
@ -485,31 +491,34 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
|
|||
}
|
||||
}
|
||||
|
||||
fn never_loop(block: &Block, id: NodeId) -> bool {
|
||||
!contains_continue_block(block, Some(id)) && loop_exit_block(block, &mut vec![id])
|
||||
struct NeverLoopState {
|
||||
breaks: HashSet<NodeId>,
|
||||
continues: HashSet<NodeId>,
|
||||
}
|
||||
|
||||
fn loop_exit_block(block: &Block, loops: &mut Vec<NodeId>) -> bool {
|
||||
block.stmts.iter().take_while(|s| !contains_continue_stmt(s, None)).any(|s| loop_exit_stmt(s, loops))
|
||||
|| block.expr.as_ref().map_or(false, |e| loop_exit_expr(e, loops))
|
||||
fn never_loop_block(block: &Block, state: &mut NeverLoopState) -> bool {
|
||||
let stmts = block.stmts.iter().map(stmt_to_expr);
|
||||
let expr = once(block.expr.as_ref().map(|p| &**p));
|
||||
let mut iter = stmts.chain(expr).filter_map(|e| e);
|
||||
never_loop_expr_seq(&mut iter, state)
|
||||
}
|
||||
|
||||
fn loop_exit_stmt(stmt: &Stmt, loops: &mut Vec<NodeId>) -> bool {
|
||||
fn stmt_to_expr(stmt: &Stmt) -> Option<&Expr> {
|
||||
match stmt.node {
|
||||
StmtSemi(ref e, _) |
|
||||
StmtExpr(ref e, _) => loop_exit_expr(e, loops),
|
||||
StmtDecl(ref d, _) => loop_exit_decl(d, loops),
|
||||
StmtSemi(ref e, ..) |
|
||||
StmtExpr(ref e, ..) => Some(e),
|
||||
StmtDecl(ref d, ..) => decl_to_expr(d),
|
||||
}
|
||||
}
|
||||
|
||||
fn loop_exit_decl(decl: &Decl, loops: &mut Vec<NodeId>) -> bool {
|
||||
fn decl_to_expr(decl: &Decl) -> Option<&Expr> {
|
||||
match decl.node {
|
||||
DeclLocal(ref local) => local.init.as_ref().map_or(false, |e| loop_exit_expr(e, loops)),
|
||||
_ => false,
|
||||
DeclLocal(ref local) => local.init.as_ref().map(|p| &**p),
|
||||
_ => None,
|
||||
}
|
||||
}
|
||||
|
||||
fn loop_exit_expr(expr: &Expr, loops: &mut Vec<NodeId>) -> bool {
|
||||
fn never_loop_expr(expr: &Expr, state: &mut NeverLoopState) -> bool {
|
||||
match expr.node {
|
||||
ExprBox(ref e) |
|
||||
ExprUnary(_, ref e) |
|
||||
|
|
@ -518,38 +527,73 @@ fn loop_exit_expr(expr: &Expr, loops: &mut Vec<NodeId>) -> bool {
|
|||
ExprField(ref e, _) |
|
||||
ExprTupField(ref e, _) |
|
||||
ExprAddrOf(_, ref e) |
|
||||
ExprRepeat(ref e, _) => loop_exit_expr(e, loops),
|
||||
ExprRepeat(ref e, _) => never_loop_expr(e, state),
|
||||
ExprArray(ref es) |
|
||||
ExprMethodCall(_, _, ref es) |
|
||||
ExprTup(ref es) => es.iter().any(|e| loop_exit_expr(e, loops)),
|
||||
ExprCall(ref e, ref es) => loop_exit_expr(e, loops) || es.iter().any(|e| loop_exit_expr(e, loops)),
|
||||
ExprTup(ref es) => never_loop_expr_seq(&mut es.iter(), state),
|
||||
ExprCall(ref e, ref es) => never_loop_expr_seq(&mut once(&**e).chain(es.iter()), state),
|
||||
ExprBinary(_, ref e1, ref e2) |
|
||||
ExprAssign(ref e1, ref e2) |
|
||||
ExprAssignOp(_, ref e1, ref e2) |
|
||||
ExprIndex(ref e1, ref e2) => [e1, e2].iter().any(|e| loop_exit_expr(e, loops)),
|
||||
ExprIf(ref e, ref e2, ref e3) => loop_exit_expr(e, loops)
|
||||
|| e3.as_ref().map_or(false, |e3| loop_exit_expr(e3, loops)) && loop_exit_expr(e2, loops),
|
||||
ExprIndex(ref e1, ref e2) => never_loop_expr_seq(&mut [&**e1, &**e2].iter().cloned(), state),
|
||||
ExprIf(ref e, ref e2, ref e3) => {
|
||||
let e1 = never_loop_expr(e, state);
|
||||
let e2 = never_loop_expr(e2, state);
|
||||
match *e3 {
|
||||
Some(ref e3) => {
|
||||
let e3 = never_loop_expr(e3, state);
|
||||
e1 && (e2 || e3)
|
||||
},
|
||||
None => e1,
|
||||
}
|
||||
},
|
||||
ExprLoop(ref b, _, _) => {
|
||||
loops.push(expr.id);
|
||||
let val = loop_exit_block(b, loops);
|
||||
loops.pop();
|
||||
val
|
||||
let block_may_complete = never_loop_block(b, state);
|
||||
let has_break = state.breaks.remove(&expr.id);
|
||||
state.continues.remove(&expr.id);
|
||||
block_may_complete || has_break
|
||||
},
|
||||
ExprWhile(ref e, ref b, _) => {
|
||||
loops.push(expr.id);
|
||||
let val = loop_exit_expr(e, loops) || loop_exit_block(b, loops);
|
||||
loops.pop();
|
||||
val
|
||||
let e = never_loop_expr(e, state);
|
||||
let block_may_complete = never_loop_block(b, state);
|
||||
let has_break = state.breaks.remove(&expr.id);
|
||||
let has_continue = state.continues.remove(&expr.id);
|
||||
e && (block_may_complete || has_break || has_continue)
|
||||
},
|
||||
ExprMatch(ref e, ref arms, _) => loop_exit_expr(e, loops) || arms.iter().all(|a| loop_exit_expr(&a.body, loops)),
|
||||
ExprBlock(ref b) => loop_exit_block(b, loops),
|
||||
ExprAgain(d) => d.target_id.opt_id().map_or(false, |id| loops.iter().skip(1).all(|&id2| id != id2)),
|
||||
ExprBreak(d, _) => d.target_id.opt_id().map_or(false, |id| loops[0] == id),
|
||||
ExprRet(_) => true,
|
||||
_ => false,
|
||||
ExprMatch(ref e, ref arms, _) => {
|
||||
let e = never_loop_expr(e, state);
|
||||
let arms = never_loop_expr_branch(&mut arms.iter().map(|a| &*a.body), state);
|
||||
e && arms
|
||||
},
|
||||
ExprBlock(ref b) => never_loop_block(b, state),
|
||||
ExprAgain(d) => {
|
||||
let id = d.target_id.opt_id().expect("continue is missing target id");
|
||||
state.continues.insert(id);
|
||||
false
|
||||
},
|
||||
ExprBreak(d, _) => {
|
||||
let id = d.target_id.opt_id().expect("break is missing target id");
|
||||
state.breaks.insert(id);
|
||||
false
|
||||
},
|
||||
ExprRet(ref e) => {
|
||||
if let Some(ref e) = *e {
|
||||
never_loop_expr(e, state);
|
||||
}
|
||||
false
|
||||
},
|
||||
_ => true,
|
||||
}
|
||||
}
|
||||
|
||||
fn never_loop_expr_seq<'a, T: Iterator<Item=&'a Expr>>(es: &mut T, state: &mut NeverLoopState) -> bool {
|
||||
es.map(|e| never_loop_expr(e, state)).fold(true, |a, b| a && b)
|
||||
}
|
||||
|
||||
fn never_loop_expr_branch<'a, T: Iterator<Item=&'a Expr>>(e: &mut T, state: &mut NeverLoopState) -> bool {
|
||||
e.map(|e| never_loop_expr(e, state)).fold(false, |a, b| a || b)
|
||||
}
|
||||
|
||||
fn check_for_loop<'a, 'tcx>(
|
||||
cx: &LateContext<'a, 'tcx>,
|
||||
pat: &'tcx Pat,
|
||||
|
|
|
|||
|
|
@ -68,3 +68,15 @@ error: this loop never actually loops
|
|||
103 | | }
|
||||
| |_____^
|
||||
|
||||
error: this loop never actually loops
|
||||
--> $DIR/never_loop.rs:144:5
|
||||
|
|
||||
144 | / 'outer: while a { // never loops
|
||||
145 | | while a {
|
||||
146 | | if a {
|
||||
147 | | a = false;
|
||||
... |
|
||||
151 | | break 'outer;
|
||||
152 | | }
|
||||
| |_____^
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue