I've been doing a bit of debugging on this myself. From what I can tell, the relative path of the file found from the SourcePath needs to match part of the end path of the path embedded in the PDB. For example:
I have a file on disk at:
C:\Users\User\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\std\src\sys\windows\thread_local_key.rs
The path of the file embedded in the PDB is:
/rustc/c09a9529c51cde41c1101e56049d418edb07bf71\/library\std\src\sys\windows\thread_local_key.rs
✔ This SourcePath, and any below it, correctly finds the file:
C:\Users\User\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust
❌ This SourcePath, and any above it, does not find the file:
C:\Users\User\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src
Notice how with the failure case, the relative path to the file would begin with library\
. The library
path component is the first part of the path that is not found in the embedded path. I assume it does a path check for every relative address, recursively:
thread_local_key.rs
windows\thread_local_key.rs
sys\windows\thread_local_key.rs
src\sys\windows\thread_local_key.rs
std\src\sys\windows\thread_local_key.rs
library\std\src\sys\windows\thread_local_key.rs
etc.