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fix dead_code on block-scoped function under "use strict" (#2006)

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Technically not part of ES5, but commonly used code exists in the wild.
This commit is contained in:
Alex Lam S.L
2017-05-26 16:08:51 +08:00
committed by GitHub
parent c70fb60384
commit dc33facfcb
3 changed files with 220 additions and 3 deletions
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2
lib/compress.js
View File

@@ -1222,7 +1222,7 @@ merge(Compressor.prototype, {
target.push(node);
return true;
}
if (node instanceof AST_Defun) {
if (node instanceof AST_Defun && (node === stat || !compressor.has_directive("use strict"))) {
target.push(node);
return true;
}

87
test/compress/dead-code.js
View File

@@ -31,7 +31,7 @@ dead_code_2_should_warn: {
function f() {
g();
x = 10;
throw "foo";
throw new Error("foo");
// completely discarding the `if` would introduce some
// bugs. UglifyJS v1 doesn't deal with this issue; in v2
// we copy any declarations to the upper scope.
@@ -46,16 +46,60 @@ dead_code_2_should_warn: {
})();
}
}
f();
}
expect: {
function f() {
g();
x = 10;
throw "foo";
throw new Error("foo");
var x;
function g(){};
}
f();
}
expect_stdout: true
node_version: "<=4"
}
dead_code_2_should_warn_strict: {
options = {
dead_code: true
};
input: {
"use strict";
function f() {
g();
x = 10;
throw new Error("foo");
// completely discarding the `if` would introduce some
// bugs. UglifyJS v1 doesn't deal with this issue; in v2
// we copy any declarations to the upper scope.
if (x) {
y();
var x;
function g(){};
// but nested declarations should not be kept.
(function(){
var q;
function y(){};
})();
}
}
f();
}
expect: {
"use strict";
function f() {
g();
x = 10;
throw new Error("foo");
var x;
}
f();
}
expect_stdout: true
node_version: "=4"
}
dead_code_constant_boolean_should_warn_more: {
@@ -78,6 +122,7 @@ dead_code_constant_boolean_should_warn_more: {
foo();
var moo;
}
bar();
}
expect: {
var foo;
@@ -86,8 +131,46 @@ dead_code_constant_boolean_should_warn_more: {
// as for the for, it should keep:
var x = 10, y;
var moo;
bar();
}
expect_stdout: true
node_version: "<=4"
}
dead_code_constant_boolean_should_warn_more_strict: {
options = {
dead_code : true,
loops : true,
booleans : true,
conditionals : true,
evaluate : true,
side_effects : true,
};
input: {
"use strict";
while (!((foo && bar) || (x + "0"))) {
console.log("unreachable");
var foo;
function bar() {}
}
for (var x = 10, y; x && (y || x) && (!typeof x); ++x) {
asdf();
foo();
var moo;
}
bar();
}
expect: {
"use strict";
var foo;
// nothing for the while
// as for the for, it should keep:
var x = 10, y;
var moo;
bar();
}
expect_stdout: true
node_version: ">=4"
}
try_catch_finally: {

134
test/compress/issue-1034.js
View File

@@ -116,3 +116,137 @@ non_hoisted_function_after_return_2b: {
"WARN: Dropping unreachable code [test/compress/issue-1034.js:101,12]",
]
}
non_hoisted_function_after_return_strict: {
options = {
hoist_funs: false, dead_code: true, conditionals: true, comparisons: true,
evaluate: true, booleans: true, loops: true, unused: true, keep_fargs: true,
if_return: true, join_vars: true, cascade: true, side_effects: true
}
input: {
"use strict";
function foo(x) {
if (x) {
return bar();
not_called1();
} else {
return baz();
not_called2();
}
function bar() { return 7; }
return not_reached;
function UnusedFunction() {}
function baz() { return 8; }
}
console.log(foo(0), foo(1));
}
expect: {
"use strict";
function foo(x) {
return x ? bar() : baz();
function bar() { return 7 }
function baz() { return 8 }
}
console.log(foo(0), foo(1));
}
expect_stdout: "8 7"
expect_warnings: [
'WARN: Dropping unreachable code [test/compress/issue-1034.js:131,16]',
"WARN: Dropping unreachable code [test/compress/issue-1034.js:134,16]",
"WARN: Dropping unreachable code [test/compress/issue-1034.js:137,12]",
"WARN: Dropping unused function UnusedFunction [test/compress/issue-1034.js:138,21]"
]
}
non_hoisted_function_after_return_2a_strict: {
options = {
hoist_funs: false, dead_code: true, conditionals: true, comparisons: true,
evaluate: true, booleans: true, loops: true, unused: true, keep_fargs: true,
if_return: true, join_vars: true, cascade: true, side_effects: true,
collapse_vars: false, passes: 2, warnings: "verbose"
}
input: {
"use strict";
function foo(x) {
if (x) {
return bar(1);
var a = not_called(1);
} else {
return bar(2);
var b = not_called(2);
}
var c = bar(3);
function bar(x) { return 7 - x; }
function nope() {}
return b || c;
}
console.log(foo(0), foo(1));
}
expect: {
"use strict";
function foo(x) {
return bar(x ? 1 : 2);
function bar(x) {
return 7 - x;
}
}
console.log(foo(0), foo(1));
}
expect_stdout: "5 6"
expect_warnings: [
"WARN: Dropping unreachable code [test/compress/issue-1034.js:173,16]",
"WARN: Declarations in unreachable code! [test/compress/issue-1034.js:173,16]",
"WARN: Dropping unreachable code [test/compress/issue-1034.js:176,16]",
"WARN: Declarations in unreachable code! [test/compress/issue-1034.js:176,16]",
"WARN: Dropping unused variable a [test/compress/issue-1034.js:173,20]",
"WARN: Dropping unused function nope [test/compress/issue-1034.js:180,21]",
"WARN: Dropping unreachable code [test/compress/issue-1034.js:178,12]",
"WARN: Declarations in unreachable code! [test/compress/issue-1034.js:178,12]",
"WARN: Dropping unreachable code [test/compress/issue-1034.js:181,12]",
"WARN: Dropping unused variable b [test/compress/issue-1034.js:176,20]",
"WARN: Dropping unused variable c [test/compress/issue-1034.js:178,16]",
]
}
non_hoisted_function_after_return_2b_strict: {
options = {
hoist_funs: false, dead_code: true, conditionals: true, comparisons: true,
evaluate: true, booleans: true, loops: true, unused: true, keep_fargs: true,
if_return: true, join_vars: true, cascade: true, side_effects: true,
collapse_vars: false
}
input: {
"use strict";
function foo(x) {
if (x) {
return bar(1);
} else {
return bar(2);
var b;
}
var c = bar(3);
function bar(x) {
return 7 - x;
}
return b || c;
}
console.log(foo(0), foo(1));
}
expect: {
"use strict";
function foo(x) {
return bar(x ? 1 : 2);
function bar(x) { return 7 - x; }
}
console.log(foo(0), foo(1));
}
expect_stdout: "5 6"
expect_warnings: [
// duplicate warnings no longer emitted
"WARN: Dropping unreachable code [test/compress/issue-1034.js:225,16]",
"WARN: Declarations in unreachable code! [test/compress/issue-1034.js:225,16]",
"WARN: Dropping unreachable code [test/compress/issue-1034.js:227,12]",
"WARN: Declarations in unreachable code! [test/compress/issue-1034.js:227,12]",
"WARN: Dropping unreachable code [test/compress/issue-1034.js:231,12]",
]
}