relates to:

• SR-2192 Swift's LLDB cannot import system modules and prevents debugging
• SR-2764 LLDB fails to to import a Clang module imported into Swift

Issue Description:

When C module references a header outside of module's include/ directory, lldb stops showing variable
values for the entire application.

UPDATE debugging works if C module is in a separate repository. So, this problem is only present if there are two modules in same repo's Sources/ dir.

I reproduced this with a minimal example. Steps to reproduce:

git clone https://github.com/zmeyc/lldbtest
open lldbtest.xcodeproj

Choose Main target, put the breakpoint at print() in main.swift.
Run the app.

In Debugger, choose "Show all variables".
Value of variable "i" won't be printed.
In lldb, type "p i", which will produce:

(lldb) p i
warning: Swift error in module Main.
Debug info from this module will be unavailable in the debugger.

error: in auto-import:
failed to get module 'Main' from AST context:

Detailed description:

I created a Swift app with the following structure:

lldbtest
  ThirdParty
    thirdpartylib.h - a header file from some third-party library.
  Source
    CLib - a C module which includes <thirdpartylib.h> and exposes it to Swift code.
    Main - main.swift which calls a function from thirdpartylib

The app compiles and works fine from console:

swift build -Xcc -I"$(shell pwd)/ThirdParty"

If you want to regenerate the xcodeproj:

rm -rf lldbtest.xcodeproj
swift package generate-xcodeproj
open lldbtest.xcodeproj
Select "Main" target -> Build Settings.
Add "$(SRCROOT)/ThirdParty" to Header Search Paths.
Add "$(SRCROOT)/Sources/CLib" to Import Paths.

The app will now compile and run, but debugging won't work.