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fix corner case in loops & unused (#4092)

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fixes #4091
This commit is contained in:
Alex Lam S.L
2020-09-03 18:51:26 +01:00
committed by GitHub
parent 980fcbb56b
commit 6e235602fb
2 changed files with 77 additions and 15 deletions
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41
lib/compress.js
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@@ -4642,16 +4642,7 @@ merge(Compressor.prototype, {
body: make_sequence(node, side_effects)
}));
}
switch (body.length) {
case 0:
return in_list ? List.skip : make_node(AST_EmptyStatement, node);
case 1:
return body[0];
default:
return in_list ? List.splice(body) : make_node(AST_BlockStatement, node, {
body: body
});
}
return insert_statements(body, node, in_list);
}
if (node instanceof AST_LabeledStatement && node.body instanceof AST_For) {
// Certain combination of unused name + side effect leads to invalid AST:
@@ -4714,12 +4705,19 @@ merge(Compressor.prototype, {
if (def.id in in_use_ids) return;
if (def.scope !== self && member(def, self.enclosed)) return;
log(sym, "Dropping unused loop variable {name}");
if (for_ins[def.id] === node) delete for_ins[def.id];
var body = [];
var value = node.object.drop_side_effect_free(compressor);
if (!value) return in_list ? List.skip : make_node(AST_EmptyStatement, node);
AST_Node.warn("Side effects in object of for-in loop [{file}:{line},{col}]", value.start);
return make_node(AST_SimpleStatement, node, {
body: value
});
if (value) {
AST_Node.warn("Side effects in object of for-in loop [{file}:{line},{col}]", value.start);
body.push(make_node(AST_SimpleStatement, node, {
body: value
}));
}
if (node.init instanceof AST_Definitions && def.orig[0] instanceof AST_SymbolCatch) {
body.push(node.init);
}
return insert_statements(body, node, in_list);
} else if (node instanceof AST_Sequence) {
if (node.expressions.length == 1) return node.expressions[0];
}
@@ -4752,6 +4750,19 @@ merge(Compressor.prototype, {
};
}
function insert_statements(body, orig, in_list) {
switch (body.length) {
case 0:
return in_list ? List.skip : make_node(AST_EmptyStatement, orig);
case 1:
return body[0];
default:
return in_list ? List.splice(body) : make_node(AST_BlockStatement, orig, {
body: body
});
}
}
function track_assigns(def, node) {
if (def.scope !== self) return false;
if (!def.fixed || !node.fixed) assign_in_use[def.id] = false;