--use-strict flag doesn't apply strict mode to script

[Pravv]

• Node 12.*:
• Windows 64bit, Debian 64bit:

The --use-strict flag doesn't apply strict mode to script.
reproduction:

echo a = 1 > test.js && node --use-strict test

expected behavior:
ReferenceError: a is not defined is thrown.
behavior:
script executes without any issue.

however it works as expected when node is started first and script is called from repl.
<12 versions aren't affected.

node --use-strict
Welcome to Node.js v12.12.0.
Type ".help" for more information.
> a = 1
Thrown:
ReferenceError: a is not defined
>

[SaltyMonkey]

Tested some versions of runtime:

test.js file:

module.exports = function()  {
    a = 1;
    console.log(a);
};

Call:

PS E:\test> node --use-strict 
Welcome to Node.js v12.8.1.
Type ".help" for more information.
> let z = require(".\\test");
undefined
> z()
1

Reproduced at: 12.4, 12.6, 12.8, 12.8.1, 12.12
OS: Win 10 x64

[addaleax]

This was caused by b338edb (the switch to CompileFunctionInContext()). /cc @nodejs/v8 @hashseed @ryzokuken

[hashseed]

Fix should be easy. Just change the language mode in ParseInfo depending on FLAG_use_strict.

[targos]

@hashseed it looks like it's already done?

Refs: https://github.com/v8/v8/blob/16b83b1b4a30f4c71b3114a19926169190785f2c/src/codegen/compiler.cc#L2079-L2164

[ryzokuken]

@targos hmm, weird. By that logic, the default should be strict mode. Let me try building and debugging to see what's happening exactly.

[alexfernandez]

Any news on this? In Node.js v14.7.0 --use-strict is not working, and execution is still not strict by default.

[DVLP]

node 18.1 the problem is still there

[loynoir]

Should have some warnings like

if(has_cli_flag_use_strict) {
  switch(node_running_mode) {
    case 'repl':
    case 'script':
      throw new InValidFlagError("repl and script does not support --use_strict")
    case 'stdin':
    case 'eval':
      // OK with `--use_strict`
      break
    default:
      throw new UnreachableCaseError()
  }
}