Question

In a unit I use the function DeleteFile and the compiler outputs a hint:

‘H2443 Inline function ‘DeleteFile’ has not been expanded because unit ‘Windows’ is not specified in USES list’

In Uses there is SysUtils, which defines DeleteFile (although internally calling Windows.DeleteFile).

What does this hint mean? If I put Windows into the Uses clause, it’s gone, but I would like to understand what it is that bothers the compiler.

Answer 1

It’s an inlining restriction.

See Hallvard Vassbotn’s article about Inlined Routines.

Extracted from that site:

The rest of the inlining restrictions are common for both platforms and the most important ones are

• no inlining across package boundaries
• the inlined routine cannot access implementation section identifiers
• the call site must have access to all identifiers used in the inlined routine

Note The last point means that unless the call site unit uses the units required by the routine, the routine cannot be inlined. When this happens, the compiler emits a hint like this

 [Pascal Hint] InlinedRoutinesU.pas(14): H2443 Inline function     'InlineMe' has not been expanded because unit 'RequiredUnit'      is not specified in USES list  

To resolve the issue, add the missing unit name to the call site’s uses clause.