[Excel] Function Arguments dialog in Excel for Windows when equivalent XLL are specified

[sshukurov]

Our Excel JS addin with Custom Functions has a COM equivalent, so we have EquivalentAddins element set up in our addin's manifest for XLL compatibility. While testing our addin in a scenario when the COM equivalent is NOT installed, we came across this issue when our custom functions' definition is missing in Function Arguments dialog.

Environment

• Platform: PC desktop
• Host: Excel
• Office version number: 2108 (Build 14326.20074 Click-to-Run)
• Operating System: Microsoft Windows 10 Pro 10.0.19042 Build 19042

Expected behavior

Function Arguments dialog displays relevant information about the custom function, its arguments and result. An example of how it looks like (without XLL compatibility in the manifest):

Current behavior

Steps to reproduce

1. Create a sample addin (Excel Custom Functions) as described here.
2. Copy-paste the following snippet to manifest.xml (just before the closing tag for VersionOverrides element):

   <EquivalentAddins>
     <EquivalentAddin>
       <FileName>contosofunctions.xll</FileName>
       <Type>XLL</Type>
     </EquivalentAddin>
   </EquivalentAddins>

3. Build and start the addin in Excel for Windows.
4. Set any cell's value to =ADD(1, 2) (note that CONTOSO prefix is omitted because of XLL compatibility in place).
5. Keep the cursor on the cell and click on Insert Function button.

[grangeryy]

@sshukurov Sorry for the issue. We just did the initial investigation and seems it is a feature missed in XLL compatibility mode for custom functions. I've created a backlog to track: FEATURE 5343323