src/rules/suspicious/strict.bend source

src/rules/suspicious/strict.bend on the hub · documented module

# rule strict: a def calls itself inside an operand of `Bool.and(..)` or# `Bool.or(..)`, or in a comma-separated stretch holding `&&` or `||` (either# side of the operator), matched by that exact text# (a qualified `Base.Bool.or` is not seen). They are functions, not# short-circuits: both sides always run (timed: `False{} && f(x)` costs all of# f), so `ok(h) && go(rest)` walks the whole input after the answer is known,# and the pending operator keeps a frame per step (the JS lane overflowed at# ~64K this way). Match on the Bool in a helper, or carry it as an argument:# `go(rest, ok(h))`. A self-call bound by a let above is not flagged: binding# it says both run. Nor is one in a lambda body (`_u => go(rest)`, as# `Lazy.or_else` takes): a thunk does not run eagerly, unless the body itself# holds `&&` or `||`. A `=>` ends the stretch on its left, so a body's `&&` or# `||` never reaches back past it: `go(x) <> _u => a && b` is not flagged.import Baseimport ../../src.bend as Srcimport ../../finding.bend as Fimport ../../syntax/lex.bend as Leximport ../../syntax/tree.bend as Treeimport ../calls.bend as Callsimport ../../lazy/lazy.bend as Lazy# is the operator `&&` or `||`?def logic(+tt: String) -> Bool:  Bool.or(String.eq(tt, "&&"), String.eq(tt, "||"))# a comma or a `=>`: the end of a stretchdef seg_op.ends(kk: Lex.TokKind) -> Bool:  match kk:    case Lex.TComma{}:      True{}    case Lex.TLam{}:      True{}    case other:      False{}# this leaf's `&&` or `||`, or one further on in the stretchdef seg_op.or(+here: Bool, more: Bool) -> Bool:  Bool.or(here, more)# does the chain, up to its first top-level comma or `=>`, hold `&&` or `||`?def seg_op(nn: Tree.Node) -> Bool:  match nn:    case Tree.NCons{+h, rest}:      Lazy.stop(Bool, Calls.kind.leaf(~seg_op.ends, h), False{},        _u => seg_op.or(Bool.and(Calls.kind.leaf(~Calls.kind.oper, h), logic(Calls.leaf.text(h))), seg_op(rest)))    case other:      False{}# is the group after a name an operand: the stretch is hot, or it is the `(`# of `Bool.and` or `Bool.or`def inner(+hot: Bool, +oo: String, +tt: String) -> Bool:  Bool.or(hot, Bool.and(String.eq(oo, "("), Bool.or(String.eq(tt, "Bool.and"), String.eq(tt, "Bool.or"))))# a name, then a group: a finding when the name is the def, the group a `(`# call and the stretch hot, then what the group and the rest reportdef call(  +tt: String,  +ll: U32,  +cc: U32,  +oo: String,  +name: String,  +path: String,  +hot: Bool,  kids: List<&2, F.Finding>,  rest: List<&2, F.Finding>) -> List<&2, F.Finding>:  +more = List.concat(&2, F.Finding, [kids, rest])  Bool.pick(List<&2, F.Finding>, Bool.and(Bool.and(String.eq(oo, "("), String.eq(tt, name)), hot),    F.Finding{path, ll, cc, U32.from_nat(String.length(name)), "strict",      name ++ " calls itself inside Bool.and or Bool.or, which evaluate both sides, so there is no short-circuit; match on the Bool in a helper."} <> more,    more)# a leaf read by its kind: past a comma, past a `=>`, or past any other# token; only the branch taken runsdef leaf(  kk: Lex.TokKind,  comma: Unit -> List<&2, F.Finding>,  lam: Unit -> List<&2, F.Finding>,  plain: Unit -> List<&2, F.Finding>) -> List<&2, F.Finding>:  match kk:    case Lex.TComma{}:      comma(Unit{})    case Lex.TLam{}:      lam(Unit{})    case _k:      plain(Unit{})# the self-calls in operands: outer is whether the enclosing group is an# operand, hot whether the current comma segment is; a `=>` starts a lambda# body, hot only by its own `&&`/`||`. A leaf is read by its kind in `leaf`,# once the cell after it is knowndef walk(nn: Tree.Node, +name: String, +path: String, +outer: Bool, +hot: Bool) -> List<&2, F.Finding>:  match nn:    case Tree.NCons{Tree.Leaf{Lex.Tok{k, +t, +l, +c}}, +rest}:      match rest:        case Tree.NCons{Tree.Group{Lex.Tok{_, +o, _, _}, +kids, _}, r2}:          leaf(k, _u => walk(rest, name, path, outer, Bool.or(outer, seg_op(rest))),            _v => walk(rest, name, path, outer, seg_op(rest)),            _w => call(t, l, c, o, name, path, hot,              walk(kids, name, path, inner(hot, o, t), Bool.or(inner(hot, o, t), seg_op(kids))),              walk(r2, name, path, outer, hot)))        case _r:          leaf(k, _u => walk(rest, name, path, outer, Bool.or(outer, seg_op(rest))),            _v => walk(rest, name, path, outer, seg_op(rest)), _w => walk(rest, name, path, outer, hot))    case Tree.NCons{Tree.Group{open, +kids, close}, rest}:      List.concat(&2, F.Finding, [walk(kids, name, path, hot, Bool.or(hot, seg_op(kids))),        walk(rest, name, path, outer, hot)])    case Tree.NCons{Tree.Stmt{kind, +kids, body}, rest}:      List.concat(&2, F.Finding, [walk(kids, name, path, False{}, seg_op(kids)),        walk(body, name, path, False{}, False{}),        walk(rest, name, path, outer, hot)])    case Tree.NCons{h, rest}:      walk(rest, name, path, outer, hot)    case other:      Nil{}def check.go(ds: List<&2, Calls.Def>, +path: String, acc: List<&2, List<&2, F.Finding>>) -> List<&2, F.Finding>:  match ds:    case Nil{}:      List.concat(&2, F.Finding, List.reverse(&2, List<&2, F.Finding>, acc))    case Con{Calls.Def{+name, +sig, body}, rest}:      check.go(rest, path,        Lazy.stop(List<&2, F.Finding>, Calls.exempt(path, sig), [],          _u => walk(body, name, path, False{}, False{})) <> acc)# the ruledef check(ss: Src.Src) -> List<&2, F.Finding>:  Src.Src{path, text, toks, tree, bound, items} = ss  check.go(Calls.defs(tree), path, [])