Some statements have already been executed when debugger stops at line breakpoint

[vi34]

• Version: 14.13.1
  (also checked all major versions, 13, 12, 11, 10 – issue persists)
• Platform: MacOS
• Subsystem: Debugger

What steps will reproduce the bug?

1. Execute this script with any debugger (Chrome DevTools, VSCode, WebStorm).
2. Place line breakpoints on lines with comments.
3. Debugger stopped at the first breakpoint. (second(first()); line)
   Function first() have already been executed. – see console output
4. Resume execution
5. Debugger stopped at the second breakpoint (second(first(1)); line)
   The function first() has not yet been executed.
6. Resume execution
7. Function first() executed -> see console.

function first(x) {
    console.log("first() executed");
}

function second(x) {
    console.log("");
}

debugger;

second(first()); // place line breakpoint here

second(first(1)); // place line breakpoint here

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior?

It is expected that no statements have been executed before the debugger stopped at the line breakpoint.
Also, the behavior must be consistent. As we see it differs for second(first()); and second(first(1));

What do you see instead?

Function first has been executed before the stop at the breakpoint.

Additional information

WebStorm debugger in both cases debugger sets breakpoint with Debugger.setBreakpointByUrl method with specified lineNumber and with not specified columnNumber (which by default must work for the whole line)

Both breakpoints later resolved to the 0 column. But the order of execution may be different. So it is not possible for a debugger to set a line breakpoint which stops before any statement being executed.

The same script works perfectly in Chrome.

[pubmikeb]

I'm also facing such issue during debugging and it's very frustrating since you don't have a full control over the debugging process and can't rely on breakpoints.

Reproduced on Node.js 16 EAP/nightly.

[JoshuaHintze]

I'm seeing this in debuggers such as PHP Storm and Webstorm. Jetbrains directed me to here to vote this up.

[bosycom]

If fixing this issue really fixes debugging in PHPStorm with Node 14 then have my upvote! I hope this is fixed soon.

[HalalaiMircea]

Also using the debugger from Webstorm. Please fix this

[dario-piotrowicz]

I've tested this in both VSCode and the chrome devtools and with neither I was able to reproduce this behavior (not even using the same exact node version specified in this issue (14.13.1))

Might it be that this was an issue specific to v8 inspectors and that modern ones simply don't exhibit this anymore?

[Armanidashh]

Merge