error: use of unresolved identifier

[schwa]

This seems to be what I was seeing with #19.

I have a very simple and freshly generated package:

Example/Package.swift
Example/Sources/Example/Example.swift

Example.swift contains:

/*
```swift doctest
answer() // 42
```
*/
public func answer() -> Int {
    return 42
}

I run swift doctest from the Example directory as so:

swift doctest --verbose --package Sources/Example/Example.swift

And get the following error back out:

schwa@pan ~/D/Example> swift doctest --verbose --package Sources/Example/Example.swift
2020-05-08T08:24:06-0700 trace: Starting swift-doctest
2020-05-08T08:24:06-0700 debug: Swift launch path: /usr/bin/swift
2020-05-08T08:24:06-0700 debug: Swift launch arguments: ["run", "--repl"]
2020-05-08T08:24:06-0700 trace: Scanning /Users/schwa/Desktop/Example/Sources/Example/Example.swift for DocTest blocks
2020-05-08T08:24:06-0700 info: Found DocTest block at Sources/Example/Example.swift#3:1
answer() // 42
2020-05-08T08:24:07-0700 trace: Finished running tests.
2020-05-08T08:24:07-0700 trace: Printing test report in TAP format.
TAP version 13
1..1
not ok 1 - `answer()` produced an error
  ---
  actual: 'error: repl.swift:2:1: error: use of unresolved identifier ''answer''
  
    answer()
  
    ^~~~~~'
  column: 1
  file: Sources/Example/Example.swift
  line: 4
  ...
  ⏎                        

[schwa]

Function was originally internal. Changing it to public produces identically results though. Running Swift REPL directly and trying to import Example and run answer fails pretty much the same way:

schwa@pan ~/D/Example [1]> swift repl
error: module importing failed: invalid pathname
error: module importing failed: invalid pathname
Welcome to Apple Swift version 5.2.2 (swiftlang-1103.0.32.6 clang-1103.0.32.51).
Type :help for assistance.
  1> import Example
  2> answer()
error: repl.swift:2:1: error: use of unresolved identifier 'answer'
answer()
^~~~~~


  2> ^D

Running swift build before doesn't seem to help.

[schwa]

the error: module importing failed: invalid pathname was due to missing python modules in my .lldbinit. I've cleaned those up but am still seeing the unresolved identifier issue...

[mattt]

Thanks for the detailed write-up, @schwa. I was able to reproduce this locally.

The reason that answer is unresolved is that the code block doesn't import the Example module. I was able to get this to run successfully by adding an import statement:

/*
```swift doctest
import Example
answer() // 42
```
*/
public func answer() -> Int {
    return 42
}

$ swift doctest --verbose --package Sources/Example/Example.swift

2020-05-11T06:38:29-0700 trace: Starting swift-doctest
2020-05-11T06:38:29-0700 debug: Swift launch path: /usr/bin/swift
2020-05-11T06:38:29-0700 debug: Swift launch arguments: ["run", "--repl"]
2020-05-11T06:38:29-0700 trace: Scanning /Users/mattt/Downloads/Example/Sources/Example/Example.swift for DocTest blocks
2020-05-11T06:38:29-0700 info: Found DocTest block at Sources/Example/Example.swift#7:1
import Example
answer() // 42
2020-05-11T06:38:30-0700 trace: Finished running tests.
2020-05-11T06:38:30-0700 trace: Printing test report in TAP format.
TAP version 13
1..0⏎   

It's counter-intuitive that the execution context for code within the Example module requires an explicit import statement for itself — indeed, looking at the README, I see that I got that wrong myself in the add(_:_:) example (sorry about that!).

We can definitely improve the documentation here. Another option would be to implicitly add an import <#Module#> statement when running in a package, but this is hard to do right. Any thoughts about how this should all work?

[mattt]

#30 fixes this issue, but goes too far in its solution by running the entire source file ahead of any expectations (when not running with --package option). A more correct solution would run only the code before the doctest block, and correctly handle non-source code contexts (such as Swift example code in a text document).