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Implement ? in catch expressions #40229

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Mar 21, 2017
Merged

Implement ? in catch expressions #40229

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fc04eaa
Implement ? in catch expressions and add tests
cramertj Feb 28, 2017
1f43731
Add more catch-related CFG and lifetime tests and fix CFG bug
cramertj Mar 14, 2017
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94 changes: 72 additions & 22 deletions src/librustc/cfg/construct.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,13 +22,20 @@ struct CFGBuilder<'a, 'tcx: 'a> {
graph: CFGGraph,
fn_exit: CFGIndex,
loop_scopes: Vec<LoopScope>,
breakable_block_scopes: Vec<BlockScope>,
}

#[derive(Copy, Clone)]
struct BlockScope {
block_expr_id: ast::NodeId, // id of breakable block expr node
break_index: CFGIndex, // where to go on `break`
}

#[derive(Copy, Clone)]
struct LoopScope {
loop_id: ast::NodeId, // id of loop/while node
continue_index: CFGIndex, // where to go on a `loop`
break_index: CFGIndex, // where to go on a `break
break_index: CFGIndex, // where to go on a `break`
}

pub fn construct<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
Expand All @@ -53,6 +60,7 @@ pub fn construct<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
graph: graph,
fn_exit: fn_exit,
loop_scopes: Vec::new(),
breakable_block_scopes: Vec::new(),
};
body_exit = cfg_builder.expr(&body.value, entry);
cfg_builder.add_contained_edge(body_exit, fn_exit);
Expand All @@ -66,14 +74,34 @@ pub fn construct<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,

impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
fn block(&mut self, blk: &hir::Block, pred: CFGIndex) -> CFGIndex {
let mut stmts_exit = pred;
for stmt in &blk.stmts {
stmts_exit = self.stmt(stmt, stmts_exit);
}
if let Some(break_to_expr_id) = blk.break_to_expr_id {
let expr_exit = self.add_ast_node(blk.id, &[]);

self.breakable_block_scopes.push(BlockScope {
block_expr_id: break_to_expr_id,
break_index: expr_exit,
});

let mut stmts_exit = pred;
for stmt in &blk.stmts {
stmts_exit = self.stmt(stmt, stmts_exit);
}
let blk_expr_exit = self.opt_expr(&blk.expr, stmts_exit);
self.add_contained_edge(blk_expr_exit, expr_exit);

self.breakable_block_scopes.pop();

expr_exit
} else {
let mut stmts_exit = pred;
for stmt in &blk.stmts {
stmts_exit = self.stmt(stmt, stmts_exit);
}

let expr_exit = self.opt_expr(&blk.expr, stmts_exit);
let expr_exit = self.opt_expr(&blk.expr, stmts_exit);

self.add_ast_node(blk.id, &[expr_exit])
self.add_ast_node(blk.id, &[expr_exit])
}
}

fn stmt(&mut self, stmt: &hir::Stmt, pred: CFGIndex) -> CFGIndex {
Expand Down Expand Up @@ -295,18 +323,18 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {

hir::ExprBreak(destination, ref opt_expr) => {
let v = self.opt_expr(opt_expr, pred);
let loop_scope = self.find_scope(expr, destination);
let (scope_id, break_dest) =
self.find_scope_edge(expr, destination, ScopeCfKind::Break);
let b = self.add_ast_node(expr.id, &[v]);
self.add_exiting_edge(expr, b,
loop_scope, loop_scope.break_index);
self.add_exiting_edge(expr, b, scope_id, break_dest);
self.add_unreachable_node()
}

hir::ExprAgain(destination) => {
let loop_scope = self.find_scope(expr, destination);
let (scope_id, cont_dest) =
self.find_scope_edge(expr, destination, ScopeCfKind::Continue);
let a = self.add_ast_node(expr.id, &[pred]);
self.add_exiting_edge(expr, a,
loop_scope, loop_scope.continue_index);
self.add_exiting_edge(expr, a, scope_id, cont_dest);
self.add_unreachable_node()
}

Expand Down Expand Up @@ -552,11 +580,11 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
fn add_exiting_edge(&mut self,
from_expr: &hir::Expr,
from_index: CFGIndex,
to_loop: LoopScope,
scope_id: ast::NodeId,
to_index: CFGIndex) {
let mut data = CFGEdgeData { exiting_scopes: vec![] };
let mut scope = self.tcx.region_maps.node_extent(from_expr.id);
let target_scope = self.tcx.region_maps.node_extent(to_loop.loop_id);
let target_scope = self.tcx.region_maps.node_extent(scope_id);
while scope != target_scope {
data.exiting_scopes.push(scope.node_id(&self.tcx.region_maps));
scope = self.tcx.region_maps.encl_scope(scope);
Expand All @@ -576,20 +604,42 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
self.graph.add_edge(from_index, self.fn_exit, data);
}

fn find_scope(&self,
fn find_scope_edge(&self,
expr: &hir::Expr,
destination: hir::Destination) -> LoopScope {

match destination.loop_id.into() {
Ok(loop_id) => {
destination: hir::Destination,
scope_cf_kind: ScopeCfKind) -> (ast::NodeId, CFGIndex) {

match destination.target_id {
hir::ScopeTarget::Block(block_expr_id) => {
for b in &self.breakable_block_scopes {
if b.block_expr_id == block_expr_id {
return (block_expr_id, match scope_cf_kind {
ScopeCfKind::Break => b.break_index,
ScopeCfKind::Continue => bug!("can't continue to block"),
});
}
}
span_bug!(expr.span, "no block expr for id {}", block_expr_id);
}
hir::ScopeTarget::Loop(hir::LoopIdResult::Ok(loop_id)) => {
for l in &self.loop_scopes {
if l.loop_id == loop_id {
return *l;
return (loop_id, match scope_cf_kind {
ScopeCfKind::Break => l.break_index,
ScopeCfKind::Continue => l.continue_index,
});
}
}
span_bug!(expr.span, "no loop scope for id {}", loop_id);
}
Err(err) => span_bug!(expr.span, "loop scope error: {}", err),
hir::ScopeTarget::Loop(hir::LoopIdResult::Err(err)) =>
span_bug!(expr.span, "loop scope error: {}", err),
}
}
}

#[derive(Copy, Clone, Eq, PartialEq)]
enum ScopeCfKind {
Break,
Continue,
}
18 changes: 12 additions & 6 deletions src/librustc/hir/intravisit.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1008,18 +1008,24 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
}
ExprBreak(label, ref opt_expr) => {
label.ident.map(|ident| {
if let Ok(loop_id) = label.loop_id.into() {
visitor.visit_def_mention(Def::Label(loop_id));
}
match label.target_id {
ScopeTarget::Block(node_id) |
ScopeTarget::Loop(LoopIdResult::Ok(node_id)) =>
visitor.visit_def_mention(Def::Label(node_id)),
ScopeTarget::Loop(LoopIdResult::Err(_)) => {},
};
visitor.visit_name(ident.span, ident.node.name);
});
walk_list!(visitor, visit_expr, opt_expr);
}
ExprAgain(label) => {
label.ident.map(|ident| {
if let Ok(loop_id) = label.loop_id.into() {
visitor.visit_def_mention(Def::Label(loop_id));
}
match label.target_id {
ScopeTarget::Block(_) => bug!("can't `continue` to a non-loop block"),
ScopeTarget::Loop(LoopIdResult::Ok(node_id)) =>
visitor.visit_def_mention(Def::Label(node_id)),
ScopeTarget::Loop(LoopIdResult::Err(_)) => {},
};
visitor.visit_name(ident.span, ident.node.name);
});
}
Expand Down
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