1435524 - Inconsistent behaviour when setting breakpoints at the start of "if" expressions

Status: RESOLVED DUPLICATE of bug 1435519

(Firefox :: Untriaged, defect)

Description

[hbenl]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0
Build ID: 20180130084414

Steps to reproduce:

I'm trying to set a breakpoint at the first line of the following statement:

if (true) {
  console.log("Foo! Bar!");
}



Actual results:

Depending on the context of that statement the breakpoint is either set on the first line or is moved to the second line (to the console.log statement).


Expected results:

The breakpoint should always be set at the first line

Comment 1

[hbenl]

Here's an example:

// Breakpoint is moved
if (true) {
  console.log("Foo! Bar!");
}

// Breakpoint is moved
function f1() {
  if (true) {
    console.log("Foo! Bar!");
  }
}

// Breakpoint is *not* moved
function f2() {
  if (true) {
    console.log("Foo! Bar!");
  }
  let x;
}

// Breakpoint is moved
function f3() {
  if (true) {
    console.log("Foo! Bar!");
  }
  var x;
}

Comment 2

[hbenl]

Correction: in the first part of the example, the breakpoint is not moved in the Firefox devtools,
but it is moved when I use the VS Code debug adapter for Firefox
(https://marketplace.visualstudio.com/items?itemName=hbenl.vscode-firefox-debug) with Firefox 58.0.1,
but not with Firefox 59.0b6.

This may also be related to https://bugzilla.mozilla.org/show_bug.cgi?id=1435519

Comment 3

[Cristina Badescu [:cbadescu], Experiments QA]

I think that this issue is very similar as the one filed in bug 1435519, so I'm marking this one as Resolved-Duplicated.