Incorrect unused import warning involving templates and tables

[Jjp137]

The following example results in an unused import warning being incorrectly reported.

Example

Two small modules are involved in this example.

first.nim:

import tables, second

template test(key: int): int =
  data[key]

echo test(1)

second.nim:

import tables

let data* = {1: 2, 3: 4}.toTable

Build with nim c first.nim.

Current Output

Among the usual compiler output:

first.nim(1, 16) Warning: imported and not used: 'second' [UnusedImport]

Expected Output

Since data is used, that warning should not appear. Removing the import as the warning suggests causes the program to fail to compile.

Additional Information

The incorrect unused import warning does not appear if any one of these is true:

• The template is a proc instead
• The template's body is changed to data.len
• The table was replaced with something simpler such as let x* = 5, and the template's body was changed to just x

Output of nim -v:

Nim Compiler Version 1.1.1 [Linux: amd64]
Compiled at 2019-12-12
Copyright (c) 2006-2019 by Andreas Rumpf

git hash: 94289161f9dd00b2fc3070b08895a3b6c557ef44
active boot switches: -d:release

Also occurs with 1.0.4.