diff --git a/src/librustc/hir/pat_util.rs b/src/librustc/hir/pat_util.rs index 3d82f37e1a9..b68886ba62c 100644 --- a/src/librustc/hir/pat_util.rs +++ b/src/librustc/hir/pat_util.rs @@ -77,6 +77,34 @@ impl hir::Pat { }); } + /// Call `f` on every "binding" in a pattern, e.g., on `a` in + /// `match foo() { Some(a) => (), None => () }`. + /// + /// When encountering an or-pattern `p_0 | ... | p_n` only `p_0` will be visited. + pub fn each_binding_or_first(&self, c: &mut F) + where F: FnMut(hir::BindingAnnotation, HirId, Span, ast::Ident), + { + match &self.node { + PatKind::Binding(bm, _, ident, sub) => { + c(*bm, self.hir_id, self.span, *ident); + sub.iter().for_each(|p| p.each_binding_or_first(c)); + } + PatKind::Or(ps) => ps[0].each_binding_or_first(c), + PatKind::Struct(_, fs, _) => fs.iter().for_each(|f| f.pat.each_binding_or_first(c)), + PatKind::TupleStruct(_, ps, _) | PatKind::Tuple(ps, _) => { + ps.iter().for_each(|p| p.each_binding_or_first(c)); + } + PatKind::Box(p) | PatKind::Ref(p, _) => p.each_binding_or_first(c), + PatKind::Slice(before, slice, after) => { + before.iter() + .chain(slice.iter()) + .chain(after.iter()) + .for_each(|p| p.each_binding_or_first(c)); + } + PatKind::Wild | PatKind::Lit(_) | PatKind::Range(..) | PatKind::Path(_) => {} + } + } + /// Checks if the pattern contains any patterns that bind something to /// an ident, e.g., `foo`, or `Foo(foo)` or `foo @ Bar(..)`. pub fn contains_bindings(&self) -> bool { diff --git a/src/librustc/middle/liveness.rs b/src/librustc/middle/liveness.rs index 3c264f9ac6e..9afd147ae34 100644 --- a/src/librustc/middle/liveness.rs +++ b/src/librustc/middle/liveness.rs @@ -96,7 +96,11 @@ use self::LiveNodeKind::*; use self::VarKind::*; +use crate::hir; +use crate::hir::{Expr, HirId}; use crate::hir::def::*; +use crate::hir::def_id::DefId; +use crate::hir::intravisit::{self, Visitor, FnKind, NestedVisitorMap}; use crate::hir::Node; use crate::hir::ptr::P; use crate::ty::{self, TyCtxt}; @@ -105,20 +109,16 @@ use crate::lint; use crate::util::nodemap::{HirIdMap, HirIdSet}; use errors::Applicability; -use std::collections::{BTreeMap, VecDeque}; +use rustc_data_structures::fx::FxIndexMap; +use std::collections::VecDeque; use std::{fmt, u32}; use std::io::prelude::*; use std::io; use std::rc::Rc; use syntax::ast; -use syntax::symbol::{kw, sym}; +use syntax::symbol::sym; use syntax_pos::Span; -use crate::hir; -use crate::hir::{Expr, HirId}; -use crate::hir::def_id::DefId; -use crate::hir::intravisit::{self, Visitor, FnKind, NestedVisitorMap}; - #[derive(Copy, Clone, PartialEq)] struct Variable(u32); @@ -727,35 +727,15 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> { self.ir.variable(hir_id, span) } - fn pat_bindings(&mut self, pat: &hir::Pat, mut f: F) where - F: FnMut(&mut Liveness<'a, 'tcx>, LiveNode, Variable, Span, HirId), - { - pat.each_binding(|_bm, hir_id, sp, n| { - let ln = self.live_node(hir_id, sp); - let var = self.variable(hir_id, n.span); - f(self, ln, var, n.span, hir_id); - }) - } - - fn arm_pats_bindings(&mut self, pat: Option<&hir::Pat>, f: F) where - F: FnMut(&mut Liveness<'a, 'tcx>, LiveNode, Variable, Span, HirId), - { - if let Some(pat) = pat { - self.pat_bindings(pat, f); - } - } - - fn define_bindings_in_pat(&mut self, pat: &hir::Pat, succ: LiveNode) - -> LiveNode { - self.define_bindings_in_arm_pats(Some(pat), succ) - } - - fn define_bindings_in_arm_pats(&mut self, pat: Option<&hir::Pat>, succ: LiveNode) - -> LiveNode { - let mut succ = succ; - self.arm_pats_bindings(pat, |this, ln, var, _sp, _id| { - this.init_from_succ(ln, succ); - this.define(ln, var); + fn define_bindings_in_pat(&mut self, pat: &hir::Pat, mut succ: LiveNode) -> LiveNode { + // In an or-pattern, only consider the first pattern; any later patterns + // must have the same bindings, and we also consider the first pattern + // to be the "authoritative" set of ids. + pat.each_binding_or_first(&mut |_, hir_id, pat_sp, ident| { + let ln = self.live_node(hir_id, pat_sp); + let var = self.variable(hir_id, ident.span); + self.init_from_succ(ln, succ); + self.define(ln, var); succ = ln; }); succ @@ -1069,12 +1049,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> { arm.guard.as_ref().map(|hir::Guard::If(e)| &**e), body_succ ); - // only consider the first pattern; any later patterns must have - // the same bindings, and we also consider the first pattern to be - // the "authoritative" set of ids - let arm_succ = - self.define_bindings_in_arm_pats(arm.top_pats_hack().first().map(|p| &**p), - guard_succ); + let arm_succ = self.define_bindings_in_pat(&arm.pat, guard_succ); self.merge_from_succ(ln, arm_succ, first_merge); first_merge = false; }; @@ -1381,74 +1356,36 @@ impl<'a, 'tcx> Visitor<'tcx> for Liveness<'a, 'tcx> { NestedVisitorMap::None } - fn visit_local(&mut self, l: &'tcx hir::Local) { - check_local(self, l); + fn visit_local(&mut self, local: &'tcx hir::Local) { + self.check_unused_vars_in_pat(&local.pat, None, |spans, hir_id, ln, var| { + if local.init.is_some() { + self.warn_about_dead_assign(spans, hir_id, ln, var); + } + }); + + intravisit::walk_local(self, local); } + fn visit_expr(&mut self, ex: &'tcx Expr) { check_expr(self, ex); } - fn visit_arm(&mut self, a: &'tcx hir::Arm) { - check_arm(self, a); + + fn visit_arm(&mut self, arm: &'tcx hir::Arm) { + self.check_unused_vars_in_pat(&arm.pat, None, |_, _, _, _| {}); + intravisit::walk_arm(self, arm); } } -fn check_local<'a, 'tcx>(this: &mut Liveness<'a, 'tcx>, local: &'tcx hir::Local) { - match local.init { - Some(_) => { - this.warn_about_unused_or_dead_vars_in_pat(&local.pat); - }, - None => { - this.pat_bindings(&local.pat, |this, ln, var, sp, id| { - let span = local.pat.simple_ident().map_or(sp, |ident| ident.span); - this.warn_about_unused(vec![span], id, ln, var); - }) - } - } - - intravisit::walk_local(this, local); -} - -fn check_arm<'a, 'tcx>(this: &mut Liveness<'a, 'tcx>, arm: &'tcx hir::Arm) { - // Only consider the variable from the first pattern; any later patterns must have - // the same bindings, and we also consider the first pattern to be the "authoritative" set of - // ids. However, we should take the spans of variables with the same name from the later - // patterns so the suggestions to prefix with underscores will apply to those too. - let mut vars: BTreeMap)> = Default::default(); - - for pat in arm.top_pats_hack() { - this.arm_pats_bindings(Some(&*pat), |this, ln, var, sp, id| { - let name = this.ir.variable_name(var); - vars.entry(name) - .and_modify(|(.., spans)| { - spans.push(sp); - }) - .or_insert_with(|| { - (ln, var, id, vec![sp]) - }); - }); - } - - for (_, (ln, var, id, spans)) in vars { - this.warn_about_unused(spans, id, ln, var); - } - - intravisit::walk_arm(this, arm); -} - -fn check_expr<'a, 'tcx>(this: &mut Liveness<'a, 'tcx>, expr: &'tcx Expr) { +fn check_expr<'tcx>(this: &mut Liveness<'_, 'tcx>, expr: &'tcx Expr) { match expr.node { hir::ExprKind::Assign(ref l, _) => { this.check_place(&l); - - intravisit::walk_expr(this, expr); } hir::ExprKind::AssignOp(_, ref l, _) => { if !this.tables.is_method_call(expr) { this.check_place(&l); } - - intravisit::walk_expr(this, expr); } hir::ExprKind::InlineAsm(ref ia, ref outputs, ref inputs) => { @@ -1463,8 +1400,6 @@ fn check_expr<'a, 'tcx>(this: &mut Liveness<'a, 'tcx>, expr: &'tcx Expr) { } this.visit_expr(output); } - - intravisit::walk_expr(this, expr); } // no correctness conditions related to liveness @@ -1477,13 +1412,13 @@ fn check_expr<'a, 'tcx>(this: &mut Liveness<'a, 'tcx>, expr: &'tcx Expr) { hir::ExprKind::Lit(_) | hir::ExprKind::Block(..) | hir::ExprKind::AddrOf(..) | hir::ExprKind::Struct(..) | hir::ExprKind::Repeat(..) | hir::ExprKind::Closure(..) | hir::ExprKind::Path(_) | hir::ExprKind::Yield(..) | - hir::ExprKind::Box(..) | hir::ExprKind::Type(..) | hir::ExprKind::Err => { - intravisit::walk_expr(this, expr); - } + hir::ExprKind::Box(..) | hir::ExprKind::Type(..) | hir::ExprKind::Err => {} } + + intravisit::walk_expr(this, expr); } -impl<'a, 'tcx> Liveness<'a, 'tcx> { +impl<'tcx> Liveness<'_, 'tcx> { fn check_place(&mut self, expr: &'tcx Expr) { match expr.node { hir::ExprKind::Path(hir::QPath::Resolved(_, ref path)) => { @@ -1496,7 +1431,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> { // as being used. let ln = self.live_node(expr.hir_id, expr.span); let var = self.variable(var_hid, expr.span); - self.warn_about_dead_assign(expr.span, expr.hir_id, ln, var); + self.warn_about_dead_assign(vec![expr.span], expr.hir_id, ln, var); } } } @@ -1518,109 +1453,112 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> { } fn warn_about_unused_args(&self, body: &hir::Body, entry_ln: LiveNode) { - for param in &body.params { - param.pat.each_binding(|_bm, hir_id, _, ident| { - let sp = ident.span; - let var = self.variable(hir_id, sp); - // Ignore unused self. - if ident.name != kw::SelfLower { - if !self.warn_about_unused(vec![sp], hir_id, entry_ln, var) { - if self.live_on_entry(entry_ln, var).is_none() { - self.report_dead_assign(hir_id, sp, var, true); - } - } + for p in &body.params { + self.check_unused_vars_in_pat(&p.pat, Some(entry_ln), |spans, hir_id, ln, var| { + if self.live_on_entry(ln, var).is_none() { + self.report_dead_assign(hir_id, spans, var, true); } - }) + }); } } - fn warn_about_unused_or_dead_vars_in_pat(&mut self, pat: &hir::Pat) { - self.pat_bindings(pat, |this, ln, var, sp, id| { - if !this.warn_about_unused(vec![sp], id, ln, var) { - this.warn_about_dead_assign(sp, id, ln, var); + fn check_unused_vars_in_pat( + &self, + pat: &hir::Pat, + entry_ln: Option, + on_used_on_entry: impl Fn(Vec, HirId, LiveNode, Variable), + ) { + // In an or-pattern, only consider the variable; any later patterns must have the same + // bindings, and we also consider the first pattern to be the "authoritative" set of ids. + // However, we should take the spans of variables with the same name from the later + // patterns so the suggestions to prefix with underscores will apply to those too. + let mut vars: FxIndexMap)> = <_>::default(); + + pat.each_binding(|_, hir_id, pat_sp, ident| { + let ln = entry_ln.unwrap_or_else(|| self.live_node(hir_id, pat_sp)); + let var = self.variable(hir_id, ident.span); + vars.entry(self.ir.variable_name(var)) + .and_modify(|(.., spans)| spans.push(ident.span)) + .or_insert_with(|| (ln, var, hir_id, vec![ident.span])); + }); + + for (_, (ln, var, id, spans)) in vars { + if self.used_on_entry(ln, var) { + on_used_on_entry(spans, id, ln, var); + } else { + self.report_unused(spans, id, ln, var); } - }) + } } - fn warn_about_unused(&self, - spans: Vec, - hir_id: HirId, - ln: LiveNode, - var: Variable) - -> bool { - if !self.used_on_entry(ln, var) { - let r = self.should_warn(var); - if let Some(name) = r { - // annoying: for parameters in funcs like `fn(x: i32) - // {ret}`, there is only one node, so asking about - // assigned_on_exit() is not meaningful. - let is_assigned = if ln == self.s.exit_ln { - false - } else { - self.assigned_on_exit(ln, var).is_some() - }; + fn report_unused(&self, spans: Vec, hir_id: HirId, ln: LiveNode, var: Variable) { + if let Some(name) = self.should_warn(var).filter(|name| name != "self") { + // annoying: for parameters in funcs like `fn(x: i32) + // {ret}`, there is only one node, so asking about + // assigned_on_exit() is not meaningful. + let is_assigned = if ln == self.s.exit_ln { + false + } else { + self.assigned_on_exit(ln, var).is_some() + }; - if is_assigned { - self.ir.tcx.lint_hir_note( - lint::builtin::UNUSED_VARIABLES, - hir_id, - spans, - &format!("variable `{}` is assigned to, but never used", name), - &format!("consider using `_{}` instead", name), - ); - } else if name != "self" { - let mut err = self.ir.tcx.struct_span_lint_hir( - lint::builtin::UNUSED_VARIABLES, - hir_id, - spans.clone(), - &format!("unused variable: `{}`", name), - ); + if is_assigned { + self.ir.tcx.lint_hir_note( + lint::builtin::UNUSED_VARIABLES, + hir_id, + spans, + &format!("variable `{}` is assigned to, but never used", name), + &format!("consider using `_{}` instead", name), + ); + } else { + let mut err = self.ir.tcx.struct_span_lint_hir( + lint::builtin::UNUSED_VARIABLES, + hir_id, + spans.clone(), + &format!("unused variable: `{}`", name), + ); - if self.ir.variable_is_shorthand(var) { - if let Node::Binding(pat) = self.ir.tcx.hir().get(hir_id) { - // Handle `ref` and `ref mut`. - let spans = spans.iter() - .map(|_span| (pat.span, format!("{}: _", name))) - .collect(); + if self.ir.variable_is_shorthand(var) { + if let Node::Binding(pat) = self.ir.tcx.hir().get(hir_id) { + // Handle `ref` and `ref mut`. + let spans = spans.iter() + .map(|_span| (pat.span, format!("{}: _", name))) + .collect(); - err.multipart_suggestion( - "try ignoring the field", - spans, - Applicability::MachineApplicable, - ); - } - } else { err.multipart_suggestion( - "consider prefixing with an underscore", - spans.iter().map(|span| (*span, format!("_{}", name))).collect(), + "try ignoring the field", + spans, Applicability::MachineApplicable, ); } - - err.emit() + } else { + err.multipart_suggestion( + "consider prefixing with an underscore", + spans.iter().map(|span| (*span, format!("_{}", name))).collect(), + Applicability::MachineApplicable, + ); } + + err.emit() } - true - } else { - false } } - fn warn_about_dead_assign(&self, sp: Span, hir_id: HirId, ln: LiveNode, var: Variable) { + fn warn_about_dead_assign(&self, spans: Vec, hir_id: HirId, ln: LiveNode, var: Variable) { if self.live_on_exit(ln, var).is_none() { - self.report_dead_assign(hir_id, sp, var, false); + self.report_dead_assign(hir_id, spans, var, false); } } - fn report_dead_assign(&self, hir_id: HirId, sp: Span, var: Variable, is_argument: bool) { + fn report_dead_assign(&self, hir_id: HirId, spans: Vec, var: Variable, is_argument: bool) { if let Some(name) = self.should_warn(var) { if is_argument { - self.ir.tcx.struct_span_lint_hir(lint::builtin::UNUSED_ASSIGNMENTS, hir_id, sp, + self.ir.tcx.struct_span_lint_hir(lint::builtin::UNUSED_ASSIGNMENTS, hir_id, spans, &format!("value passed to `{}` is never read", name)) .help("maybe it is overwritten before being read?") .emit(); } else { - self.ir.tcx.struct_span_lint_hir(lint::builtin::UNUSED_ASSIGNMENTS, hir_id, sp, + self.ir.tcx.struct_span_lint_hir(lint::builtin::UNUSED_ASSIGNMENTS, hir_id, spans, &format!("value assigned to `{}` is never read", name)) .help("maybe it is overwritten before being read?") .emit();