[BUG] ndk-gdb fails with -f

[jfgoog]

Description

When running ndk-gdb -f:

Traceback (most recent call last):
  File "/home/marijn/Android/Sdk/ndk/25.1.8937393/prebuilt/linux-x86_64/bin/ndk-gdb.py", line 951, in <module>
    main()
  File "/home/marijn/Android/Sdk/ndk/25.1.8937393/prebuilt/linux-x86_64/bin/ndk-gdb.py", line 882, in main
    device.shell_nocheck(["run-as", pkg_name, "kill", "-9"] + kill_pids)
TypeError: can only concatenate list (not "map") to list

Affected versions

r25

Canary version

No response

Host OS

Windows

Host OS version

n/a

Affected ABIs

armeabi-v7a, arm64-v8a, x86, x86_64

Build system

Other (specify below)

Other build system

No response

minSdkVersion

n/a

Device API level

No response

[MarijnS95]

This is another Python 2 -> Python 3 conversion problem just like #1763:

The current code is as follows:

        kill_pids = map(str, kill_pids)
        if kill_pids:
            log("Killing processes: {}".format(", ".join(kill_pids)))
            device.shell_nocheck(["run-as", pkg_name, "kill", "-9"] + kill_pids)

In Python 2, map() returns a list which you can freely concatenate to another list. In Python 3 map() returns a lazy map object (a generator) and can't be immediately concatenated to a list. Besides, map() is discouraged in favour of generator expressions, or in this specific case a list comprehension:

kill_pids = [str(pid) for pid in kill_pids]

EDIT: You can however also use some_list.extend(<iterable, i.e. generator>) to let the list iterate a generator and append every individual item to itself.

[DanAlbert]

Whoever fixes this should extend our pylint check over this script. Pylint would have caught this.

[DanAlbert]

@appujee has uploaded a fix here: https://android-review.git.corp.google.com/c/platform/ndk/+/2579812 (thanks!)

Will leave the bug open for myself to extend pylint coverage and to update the changelog.

[MarijnS95]

https://r.android.com/c/platform/ndk/+/2579812 link for non-Googlers.

There's actually a nicer way to write this now, using the splat operator to expand one array within another array:

        kill_pids = [str(pid) for pid in kill_pids]
        if kill_pids:
            log("Killing processes: {}".format(", ".join(kill_pids)))
            device.shell_nocheck(["run-as", pkg_name, "kill", "-9", *kill_pids])

(Notice the splat operator on the last line)

---

Regarding pylint, I've seen some of the many Python linters recommend using the splat operator over +.

[DanAlbert]

https://r.android.com/c/platform/ndk/+/2579812 link for non-Googlers.

Ugh. Sorry. A while ago someone decided that my URL bar should be rewritten to something useless. I don't always remember to rewrite it by hand before pasting.

[DanAlbert]

The fix for this appears to have been in r26 beta 1 and I just forgot to add it to the changelog. In any case it's certainly in RC 1 (and I've updated the changelog).