Bogus "Undeclared Identifier" errors from the compiler?

Question

I am writing a designtime package in Delphi 2007.

I decided to move some event type declarations into their own Eventsunit so they can be used in multiple units. When I did the compiler started complaining Undeclared identifier: 'Event Name' in the units where these events were originally declared. The type declarations are all in the interface section of the Events unit and I have added the Events unit to the other units' uses clause but its like the compiler is completely ignoring the Events unit.

The IDE has no trouble finding the declarations when you CTRL + Click in the type name from another unit. Hovering the mouse over the type name displays the unit its declared in along with its parameters. Even the usually craptastic and paranoid Error Insight feature of the IDE doesn't see a problem. Only the compiler complains about it.

I tried reproducing this problem in another, simpler package project to try to isolate it but I can't reproduce it.

Has anyone else seen this behavior before and is there a work around?

Answer 1

I had already tried all the common sense suggestions like making sure the file was in the project and in the uses clause of the other units.

Since no one has posted a solution I tried Ken White's and Wouter van Nifterick's suggestions.

• closed the project and restarted the IDE - no change
• Searched every drive on my system for Events.pas or Events.dcu - the one in my project was the only one.

The only thing that worked, and I have no idea why, was to rename the Events.pas to something else. I renamed it using the Project Manager and recompiled. All the Undeclared Identifiererrors simply disappeared. I renamed it back to Events and the errors came back. Who knew?

Just out of curiosity I did a text search over every pas and inc file on my system to see if Events was used as an identifier somewhere (I know it shouldn't make a difference but... ya never know). Nothing. No variables, types or functions called Events.

As a sanity check I created a simple project with a handful of units, one of which was called Events with a few type declarations. All the other units included it in their uses clause. The compiler had no trouble resolving the type identifiers. I have absolutely no clue why it choked on the Events unit in my other project.

Update

I finally figured out why I was getting this error. The package I was writing used the open tools api(OTA) so it required the DesignIDE package. DesignIDE is provided only as a precompiled dcp and bpl so the source is missing for everything except the handful of interface units exposed as extension points for the IDE. It turns out that one of the hidden units compiled into DesignIDE is called Events. I did not discover this until I migrated my package to a later version of Delphi and started getting E2200 Package 'designide' already contains unit 'Events'. This error message did not appear in Delphi 2007.

My attempt to isolate the problem in a simpler package could not reproduce it because I had excluded the DesignIDE package from it's dependencies, not realizing that it was the source of the error.