Don't show Run/Debug button for files that don't have a main function

[suranjum]

Type: Bug

The Run button used be active only on main.dart. After an update (note sure which on), the Run button is now active on all .dart extension file, which gives error main entry not found. Either the Run button should be active only on main.dart or the extension should locate and run main.dart automatically.

Extension version: 3.64.0
VS Code version: Code 1.78.2 (b3e4e68a0bc097f0ae7907b217c1119af9e03435, 2023-05-10T14:47:05.613Z)
OS version: Linux x64 5.15.0-72-generic
Modes:
Sandboxed: Yes

System Info

Item	Value
CPUs	Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz (8 x 1800)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: disabled_off direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok video_decode: enabled video_encode: disabled_software vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: disabled_off
Load (avg)	2, 2, 1
Memory (System)	15.52GB (10.32GB free)
Process Argv	--unity-launch --crash-reporter-id 1852884f-79c8-474c-9f62-50a1ce6988de
Screen Reader	no
VM	0%
DESKTOP_SESSION	cinnamon
XDG_CURRENT_DESKTOP	X-Cinnamon
XDG_SESSION_DESKTOP	cinnamon
XDG_SESSION_TYPE	x11

[DanTup]

This is expected. There is no requirement for your entry point to be lib/main.dart so in #4429 the restrictions on when this button should show up were removed.

The button is designed to "run the current file" so it would be confusing to run a different file. There should be no loss of functionality from before, the button simple appears in more places - it will still always behave the same when clicked in a file where it used to appear.

I would recommend using F5, the Run menu, or the buttons on the Debug Sidebar if you want the usual heuristics of which file to run (which takes the open file into account, but will look for a lib/main.dart if it's not a bin/tool/test file.

Hope this makes sense!

[mindnect]

@DanTup
I accidentally clicked the run button several times. I'm new to Flutter, so I spent few hours without knowing why. I ended up hiding the button.

Shouldn't the run button only be visible when there is a main function exist? If I run it on a file without a main function, I get "Could not prepare isolate." error anyway. This change will only confuse users. I'm wondering if I'm missing something.

Thank you.

[DanTup]

I did consider this, but it's a little complicated (because the VS Code plugin doesn't itself parse Dart code and would rely on async information from the analysis server).

However, perhaps we can combine what we had before:

• if the file is something like lib/main.dart then always show the button
• otherwise, use the Outline data to see if there's a main() function

[DanTup]

For the original set of files (lib/main.dart, tool/*, bin/*) we'll continue to always show the buttons. But for other files (the ones that only recently started showing the buttons) we'll now only show it if there's a main function: