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Merge pull request #2111 from camsteffen/never_loop

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Fix never_loop
This commit is contained in:
Oliver Schneider 2017-10-06 09:10:33 +02:00 committed by GitHub
commit 12a7d1489a
2 changed files with 53 additions and 26 deletions
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65
clippy_lints/src/loops.rs
View file

@ -378,7 +378,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
match expr.node {
ExprWhile(_, ref block, _) |
ExprLoop(ref block, _, _) => {
if never_loop(block, &expr.id) {
if never_loop(block, expr.id) {
span_lint(cx, NEVER_LOOP, expr.span, "this loop never actually loops");
}
},
@ -485,11 +485,11 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
}
}
fn never_loop(block: &Block, id: &NodeId) -> bool {
!contains_continue_block(block, id) && loop_exit_block(block)
fn never_loop(block: &Block, id: NodeId) -> bool {
!contains_continue_block(block, Some(id)) && loop_exit_block(block, &mut vec![id])
}
fn contains_continue_block(block: &Block, dest: &NodeId) -> bool {
fn contains_continue_block(block: &Block, dest: Option<NodeId>) -> bool {
block.stmts.iter().any(|e| contains_continue_stmt(e, dest)) ||
block.expr.as_ref().map_or(
false,
@ -497,7 +497,7 @@ fn contains_continue_block(block: &Block, dest: &NodeId) -> bool {
)
}
fn contains_continue_stmt(stmt: &Stmt, dest: &NodeId) -> bool {
fn contains_continue_stmt(stmt: &Stmt, dest: Option<NodeId>) -> bool {
match stmt.node {
StmtSemi(ref e, _) |
StmtExpr(ref e, _) => contains_continue_expr(e, dest),
@ -505,7 +505,7 @@ fn contains_continue_stmt(stmt: &Stmt, dest: &NodeId) -> bool {
}
}
fn contains_continue_decl(decl: &Decl, dest: &NodeId) -> bool {
fn contains_continue_decl(decl: &Decl, dest: Option<NodeId>) -> bool {
match decl.node {
DeclLocal(ref local) => {
local.init.as_ref().map_or(
@ -517,7 +517,7 @@ fn contains_continue_decl(decl: &Decl, dest: &NodeId) -> bool {
}
}
fn contains_continue_expr(expr: &Expr, dest: &NodeId) -> bool {
fn contains_continue_expr(expr: &Expr, dest: Option<NodeId>) -> bool {
match expr.node {
ExprRet(Some(ref e)) |
ExprBox(ref e) |
@ -555,31 +555,32 @@ fn contains_continue_expr(expr: &Expr, dest: &NodeId) -> bool {
|e| contains_continue_expr(e, dest),
)
},
ExprAgain(d) => d.target_id.opt_id().map_or(false, |id| id == *dest),
ExprAgain(d) => dest.map_or(true, |dest| d.target_id.opt_id().map_or(false, |id| id == dest)),
_ => false,
}
}
fn loop_exit_block(block: &Block) -> bool {
block.stmts.iter().any(|e| loop_exit_stmt(e)) || block.expr.as_ref().map_or(false, |e| loop_exit_expr(e))
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 loop_exit_stmt(stmt: &Stmt) -> bool {
fn loop_exit_stmt(stmt: &Stmt, loops: &mut Vec<NodeId>) -> bool {
match stmt.node {
StmtSemi(ref e, _) |
StmtExpr(ref e, _) => loop_exit_expr(e),
StmtDecl(ref d, _) => loop_exit_decl(d),
StmtExpr(ref e, _) => loop_exit_expr(e, loops),
StmtDecl(ref d, _) => loop_exit_decl(d, loops),
}
}
fn loop_exit_decl(decl: &Decl) -> bool {
fn loop_exit_decl(decl: &Decl, loops: &mut Vec<NodeId>) -> bool {
match decl.node {
DeclLocal(ref local) => local.init.as_ref().map_or(false, |e| loop_exit_expr(e)),
DeclLocal(ref local) => local.init.as_ref().map_or(false, |e| loop_exit_expr(e, loops)),
_ => false,
}
}
fn loop_exit_expr(expr: &Expr) -> bool {
fn loop_exit_expr(expr: &Expr, loops: &mut Vec<NodeId>) -> bool {
match expr.node {
ExprBox(ref e) |
ExprUnary(_, ref e) |
@ -588,22 +589,34 @@ fn loop_exit_expr(expr: &Expr) -> bool {
ExprField(ref e, _) |
ExprTupField(ref e, _) |
ExprAddrOf(_, ref e) |
ExprRepeat(ref e, _) => loop_exit_expr(e),
ExprRepeat(ref e, _) => loop_exit_expr(e, loops),
ExprArray(ref es) |
ExprMethodCall(_, _, ref es) |
ExprTup(ref es) => es.iter().any(|e| loop_exit_expr(e)),
ExprCall(ref e, ref es) => loop_exit_expr(e) || es.iter().any(|e| loop_exit_expr(e)),
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)),
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)),
ExprIf(ref e, ref e2, ref e3) => {
loop_exit_expr(e) || e3.as_ref().map_or(false, |e| loop_exit_expr(e)) && loop_exit_expr(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),
ExprLoop(ref b, _, _) => {
loops.push(expr.id);
let val = loop_exit_block(b, loops);
loops.pop();
val
},
ExprWhile(ref e, ref b, _) => loop_exit_expr(e) || loop_exit_block(b),
ExprMatch(ref e, ref arms, _) => loop_exit_expr(e) || arms.iter().all(|a| loop_exit_expr(&a.body)),
ExprBlock(ref b) => loop_exit_block(b),
ExprBreak(_, _) | ExprAgain(_) | ExprRet(_) => true,
ExprWhile(ref e, ref b, _) => {
loops.push(expr.id);
let val = loop_exit_expr(e, loops) || loop_exit_block(b, loops);
loops.pop();
val
},
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,
}
}

14
tests/ui/never_loop.rs
View file

@ -126,6 +126,19 @@ pub fn test12(a: bool, b: bool) {
}
}
pub fn test13() {
let mut a = true;
loop { // infinite loop
while a {
if true {
a = false;
continue;
}
return;
}
}
}
fn main() {
test1();
test2();
@ -139,5 +152,6 @@ fn main() {
test10();
test11(|| 0);
test12(true, false);
test13();
}