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fix & enhance collapse_vars (#4447)

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fixes #4446
This commit is contained in:
Alex Lam S.L
2020-12-24 09:02:18 +00:00
committed by GitHub
parent 5f269cd573
commit 1896694532
7 changed files with 125 additions and 27 deletions
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50
lib/compress.js
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@@ -1542,7 +1542,7 @@ merge(Compressor.prototype, {
&& (scan_lhs && lhs.equivalent_to(node)
|| scan_rhs && (hit_rhs = scan_rhs(node, this)))) {
if (!can_replace || stop_if_hit && (hit_rhs || !lhs_local || !replace_all)) {
if (!hit_rhs || !value_def) abort = true;
if (!hit_rhs && !value_def) abort = true;
return node;
}
if (is_lhs(node, parent)) {
@@ -1595,14 +1595,28 @@ merge(Compressor.prototype, {
can_replace = false;
descend(node, scanner);
can_replace = replace;
return node;
return signal_abort(node);
}
// Scan but don't replace inside destructuring LHS
if (node instanceof AST_Assign && node.left instanceof AST_Destructured) {
var replace = can_replace;
can_replace = false;
node.left = node.left.transform(scanner);
can_replace = replace;
node.right = node.right.transform(scanner);
return signal_abort(node);
}
// Scan but don't replace inside default value
if (node instanceof AST_DefaultValue) {
node.name = node.name.transform(scanner);
var replace = can_replace;
can_replace = false;
node.value = node.value.transform(scanner);
can_replace = replace;
return signal_abort(node);
}
return handle_custom_scan_order(node, scanner);
}, function(node) {
if (abort) return;
if (stop_after === node) abort = true;
if (stop_if_hit === node) stop_if_hit = null;
});
}, signal_abort);
var multi_replacer = new TreeTransformer(function(node) {
if (abort) return node;
// Skip nodes before `candidate` as quickly as possible
@@ -1723,6 +1737,13 @@ merge(Compressor.prototype, {
}
}
function signal_abort(node) {
if (abort) return node;
if (stop_after === node) abort = true;
if (stop_if_hit === node) stop_if_hit = null;
return node;
}
function handle_custom_scan_order(node, tt) {
if (!(node instanceof AST_BlockScope)) return;
// Skip (non-executed) functions
@@ -1760,6 +1781,13 @@ merge(Compressor.prototype, {
}
}
function is_direct_assignment(node, parent) {
if (parent instanceof AST_Assign) return parent.operator == "=" && parent.left === node;
if (parent instanceof AST_DefaultValue) return parent.name === node;
if (parent instanceof AST_DestructuredArray) return true;
if (parent instanceof AST_DestructuredKeyVal) return parent.value === node;
}
function should_stop(node, parent) {
if (node === rvalue) return true;
if (parent instanceof AST_For) return node !== parent.init;
@@ -1773,7 +1801,7 @@ merge(Compressor.prototype, {
}
if (node instanceof AST_Debugger) return true;
if (node instanceof AST_Defun) return funarg && lhs.name === node.name.name;
if (node instanceof AST_Destructured) return parent instanceof AST_Assign;
if (node instanceof AST_Destructured) return (in_try || !lhs_local) && parent instanceof AST_Assign;
if (node instanceof AST_DestructuredKeyVal) return node.key instanceof AST_Node;
if (node instanceof AST_DWLoop) return true;
if (node instanceof AST_LoopControl) return true;
@@ -1784,7 +1812,7 @@ merge(Compressor.prototype, {
return !(parent instanceof AST_PropAccess && parent.expression === node)
&& is_arguments(node.definition());
}
} else if (parent instanceof AST_Assign && parent.operator == "=" && parent.left === node) {
} else if (is_direct_assignment(node, parent)) {
return false;
}
if (!replace_all) return true;
@@ -1864,9 +1892,7 @@ merge(Compressor.prototype, {
}
if (node instanceof AST_Spread) return true;
if (node instanceof AST_SymbolRef) {
if (symbol_in_lvalues(node, parent)) {
return !(parent instanceof AST_Assign && parent.operator == "=" && parent.left === node);
}
if (symbol_in_lvalues(node, parent)) return !is_direct_assignment(node, parent);
if (side_effects && may_modify(node)) return true;
var def = node.definition();
return (in_try || def.scope.resolve() !== scope) && !can_drop_symbol(node);