Symbolization issue in agent_logger

[sebmarchand]

agent_logger.exe is failing to symbolize the stack traces.

The symbolization is done in the AgentLogger::AppendTrace, this function do the following things:

1. It initialize the symbol handler via SymInitialize, this is working fine (or it at least return true)
2. It append the path of the PDB of the running process to the symbol search path. This is working fine (we successfully augment the symbol search path with the path containing the PDBs that we need).
3. It calls SymFromAddr for each line of this stack trace, this is currently failing, GetLastError returns the code 126 ("The specified module could not be found").

There's several possible culprits:

• The version of dbghelp that we're using isn't the right one.
• msdiaXXX.dll isn't registered (but it'll probably fail in the SymInitialize function if it was the case ?)
• We're doing something silly in the AppendTrace function and we've been lucky, until today.

I suspect that it has started to fail with the switch to VS2015, or to the Win10 SDK.