[5.8] Throw Error If Transaction Is Not Started While Commit

[aman00323]

This pull request has the solution to bug User commit when there is no transaction started
The current code never notify user that transaction is not started and they are trying to commit.

Current 5.8 Code

        if ($this->transactions == 1) {
            $this->getPdo()->commit();
        }
        $this->transactions = max(0, $this->transactions - 1);
        $this->fireConnectionEvent('committed');

This could be disaster if someone forget to start transaction and they trying to commit, So changes in code will throw exception. That will indicate developer that they are trying to commit but no transaction has started yet.

Changes done to code

        if ($this->transactions == 1) {
            $this->getPdo()->commit();
        } elseif ($this->transactions == 0) {
            throw new TransactionException;
        } else {
            $this->transactions = max(0, $this->transactions - 1);
            $this->fireConnectionEvent('committed');
        }

This issue is already reported here #29505, and also this issue was mention earlier by @GrahamCampbell

@taylorotwell have look at this issue and it's PR.

[mfn]

I'm still not convinced this should be pushed into a minor release (ref: #29649 (comment) ) due to the breaking change.

Even if it's currently wrong, it's never nice to break peoples app during a minor upgrade and it seems this behaviour was there for a long time so there is no "rush" (at 6.0 is around the corner was we all know).

TL;DR: IMHO this is better suited for 6.0

[mfn]

I suggest to add a message here, given more detail why it can't be commited (because none was started)

[deleugpn]

High potential for breaking several applications on a point release, no?