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fix corner case in unused (#3499)

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fixes #3497
This commit is contained in:
Alex Lam S.L
2019-10-18 20:08:05 +08:00
committed by GitHub
parent cd072317d0
commit 0201cb4b52
2 changed files with 36 additions and 7 deletions
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22
lib/compress.js
View File

@@ -2303,7 +2303,14 @@ merge(Compressor.prototype, {
return true; return true;
}); });
def(AST_Binary, function(compressor) { def(AST_Binary, function(compressor) {
return lazy_op[this.operator] && (this.left._dot_throw(compressor) || this.right._dot_throw(compressor)); switch (this.operator) {
case "&&":
return this.left._dot_throw(compressor) || this.right._dot_throw(compressor);
case "||":
return this.right._dot_throw(compressor);
default:
return false;
}
}); });
def(AST_Conditional, function(compressor) { def(AST_Conditional, function(compressor) {
return this.consequent._dot_throw(compressor) || this.alternative._dot_throw(compressor); return this.consequent._dot_throw(compressor) || this.alternative._dot_throw(compressor);
@@ -3528,10 +3535,10 @@ merge(Compressor.prototype, {
var drop_vars = !(self instanceof AST_Toplevel) || compressor.toplevel.vars; var drop_vars = !(self instanceof AST_Toplevel) || compressor.toplevel.vars;
var assign_as_unused = /keep_assign/.test(compressor.option("unused")) ? return_false : function(node, props) { var assign_as_unused = /keep_assign/.test(compressor.option("unused")) ? return_false : function(node, props) {
var sym; var sym;
if (node instanceof AST_Assign && (node.write_only || node.operator == "=")) { if (node instanceof AST_Assign) {
sym = node.left; if (node.write_only || node.operator == "=") sym = node.left;
} else if (node instanceof AST_Unary && node.write_only) { } else if (node instanceof AST_Unary) {
sym = node.expression; if (node.write_only) sym = node.expression;
} }
if (!/strict/.test(compressor.option("pure_getters"))) return sym instanceof AST_SymbolRef && sym; if (!/strict/.test(compressor.option("pure_getters"))) return sym instanceof AST_SymbolRef && sym;
while (sym instanceof AST_PropAccess && !sym.expression.may_throw_on_access(compressor)) { while (sym instanceof AST_PropAccess && !sym.expression.may_throw_on_access(compressor)) {
@@ -3637,7 +3644,7 @@ merge(Compressor.prototype, {
if (sym) { if (sym) {
var def = sym.definition(); var def = sym.definition();
var in_use = def.id in in_use_ids; var in_use = def.id in in_use_ids;
var value = null; var value;
if (node instanceof AST_Assign) { if (node instanceof AST_Assign) {
if (!in_use || node.left === sym && def.id in fixed_ids && fixed_ids[def.id] !== node) { if (!in_use || node.left === sym && def.id in fixed_ids && fixed_ids[def.id] !== node) {
value = get_rhs(node); value = get_rhs(node);
@@ -3885,6 +3892,7 @@ merge(Compressor.prototype, {
prop.walk(tw); prop.walk(tw);
}); });
if (node instanceof AST_Assign) { if (node instanceof AST_Assign) {
if (node.write_only === "p" && node.right.may_throw_on_access(compressor)) return;
var right = get_rhs(node); var right = get_rhs(node);
right.walk(tw); right.walk(tw);
if (node.left === sym) { if (node.left === sym) {
@@ -4215,7 +4223,7 @@ merge(Compressor.prototype, {
if (left instanceof AST_PropAccess) { if (left instanceof AST_PropAccess) {
var expr = left.expression; var expr = left.expression;
if (expr instanceof AST_Assign && !expr.may_throw_on_access(compressor)) { if (expr instanceof AST_Assign && !expr.may_throw_on_access(compressor)) {
expr.write_only = true; expr.write_only = "p";
} }
if (compressor.has_directive("use strict") && expr.is_constant()) return this; if (compressor.has_directive("use strict") && expr.is_constant()) return this;
} }

21
test/compress/drop-unused.js
View File

@@ -2081,3 +2081,24 @@ issue_3495: {
} }
expect_stdout: "undefined" expect_stdout: "undefined"
} }
issue_3497: {
options = {
pure_getters: "strict",
side_effects: true,
unused: true,
}
input: {
var a;
console.log(function(b) {
(b += a).p = 0;
}());
}
expect: {
var a;
console.log(function(b) {
(b += a).p = 0;
}());
}
expect_stdout: "undefined"
}