cppvsdbg can't step over Standard Library calls

[aaccioly]

Looks like Visual Code is not working as expecting when I try to Step Over a call to std::cout (F10) with Visual Studio Debugger. gdb on the other hand is working fine.

Visual Studio Code Version: 1.13.1
cpptools version: 0.12.0
Compiler: Microsoft (R) C/C++ Optimizing Compiler Version 19.00.24210 for x86
OS: Windows 7 Enterprise

Steps to reproduce:

1. Run the build_cl task (Ctrl+P task build_cl)
2. Put a breakpoint in helloworld.cpp line 5
3. Open the debug view (Ctrl+Shift+D)
4. Select configuration (Windows) Launch
5. Start Debugging (F5)
6. Step Over until the first cout instruction (F10 3 times)

What happens

Visual Studio Code can't step over this call. F10 does not advance. Debug console outputs Access violation in ntdll.dll. Call Stack displays threads Paused on Exception.

What should happen

It should step Over std::cout just like it does when we compile with task build_gcc and debug with (gdb) Launch configuration.

Example Project

helloworld.cpp

#include <iostream>

int main()
{
  int x = 10;
  int y = 20;
  std::cout << "Hello World!" << std::endl;
  std::cout << x << " " << y << std::endl;
  int z = 30;
  std::cout << z << std::endl;
}

tasks.json

{
    "version": "0.1.0",
    "tasks": [
        {
            "taskName": "build_cl",
            "command": "build.bat",
            "isShellCommand": true,
            "showOutput": "always"
        },
        {
            "taskName": "build_gcc",
            "command": "g++.exe",
            "isShellCommand": true,
            "args": ["-g", "-o", "output/hello.exe", "helloworld.cpp"],
            "showOutput": "always"
        }
    ]
}

build.bat

@echo off
cd output
call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64
set compilerflags=/Od /Zi /EHsc
set linkerflags=/OUT:hello.exe /DEBUG
cl.exe %compilerflags% ..\helloworld.cpp /link %linkerflags%

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "(gdb) Launch",
            "type": "cppdbg",
            "request": "launch",
            "program": "${workspaceRoot}/output/hello.exe",
            "args": [],
            "stopAtEntry": false,
            "cwd": "${workspaceRoot}",
            "environment": [],
            "externalConsole": true,
            "MIMode": "gdb",
            "miDebuggerPath": "gdb.exe",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ]
        },
        {
            "name": "(Windows) Launch",
            "type": "cppvsdbg",
            "request": "launch",
            "program": "${workspaceRoot}/output/hello.exe",
            "symbolSearchPath": "${workspaceRoot}/output",
            "externalConsole": true,
            "args": [],
            "stopAtEntry": false,
            "cwd": "${workspaceRoot}",
            "environment": []
        }
    ]
}

Debug logs

--------------------------------------------------------------------------------
You may only use the C/C++ Extension for Visual Studio Code with Visual Studio
Code, Visual Studio or Xamarin Studio software to help you develop and test your
applications.
--------------------------------------------------------------------------------
Loaded 'C:\Users\N662831\Documents\Projects\C-C++\test-vscode\output\hello.exe'. Symbols are loaded.
Loaded 'C:\Windows\System32\ntdll.dll'. Symbols are not loaded.
Loaded 'C:\Windows\System32\kernel32.dll'. Symbols are not loaded.
Loaded 'C:\Windows\System32\KernelBase.dll'. Symbols are not loaded.
Loaded 'C:\Windows\System32\sysfer.dll'. Symbols are not loaded.
Loaded 'C:\Windows\System32\advapi32.dll'. Symbols are not loaded.
Loaded 'C:\Windows\System32\msvcrt.dll'. Symbols are not loaded.
Loaded 'C:\Windows\System32\sechost.dll'. Symbols are not loaded.
Loaded 'C:\Windows\System32\rpcrt4.dll'. Symbols are not loaded.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000001DD540.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000001DD540.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000001DD540.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000001DD540.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000001DD540.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000001DD540.

[aaccioly]

Just to confirm the behavior in 1.14.0.
Setting up he symbolsSearchPath also does not make much difference:

Environment:

_NT_SYMBOL_PATH="srv*c:\symbols*https://msdl.microsoft.com/download/symbols"

I can see PDB files getting cached locally.

Change to launch configuration:

{
    "name": "(Windows) Launch",
    "type": "cppvsdbg",
    "request": "launch",
    "program": "${workspaceRoot}/output/hello.exe",
    "symbolSearchPath": "C:\\Symbols",
    "args": [],
    "stopAtEntry": false,
    "cwd": "${workspaceRoot}",
    "environment": [],
    "externalConsole": true
},

Debug logs

--------------------------------------------------------------------------------
You may only use the C/C++ Extension for Visual Studio Code with Visual Studio
Code, Visual Studio or Xamarin Studio software to help you develop and test your
applications.
--------------------------------------------------------------------------------
Loaded 'C:\Users\N662831\Documents\Projects\C-C++\test-vscode\output\hello.exe'. Symbols are loaded.
Loaded 'C:\Windows\System32\ntdll.dll'. Symbols are loaded.
Loaded 'C:\Windows\System32\kernel32.dll'. Symbols are loaded.
Loaded 'C:\Windows\System32\KernelBase.dll'. Symbols are loaded.
Loaded 'C:\Windows\System32\sysfer.dll'. Symbols are not loaded.
Loaded 'C:\Windows\System32\advapi32.dll'. Symbols are loaded.
Loaded 'C:\Windows\System32\msvcrt.dll'. Symbols are loaded.
Loaded 'C:\Windows\System32\sechost.dll'. Symbols are loaded.
Loaded 'C:\Windows\System32\rpcrt4.dll'. Symbols are not loaded.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x000000000017D980.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x000000000017D980.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x000000000017D980.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x000000000017D980.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x000000000017D980.
Exception thrown at 0x000007FEFCC6A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x000000000017D980.
Loaded 'C:\Windows\System32\psapi.dll'. Symbols are loaded.
Loaded 'C:\Windows\System32\api-ms-win-core-synch-l1-2-0.dll'. Symbols are not loaded.
Unloaded 'C:\Windows\System32\api-ms-win-core-synch-l1-2-0.dll'.
Loaded 'C:\Windows\System32\api-ms-win-core-synch-l1-2-0.dll'. Symbols are loaded.
Loaded 'C:\Windows\System32\privman64.dll'. Symbols are not loaded.
Exception thrown at 0x0000000076E02525 (ntdll.dll) in hello.exe: 0xC0000005: Access violation writing location 0x0000000000000000.

[pieandcakes]

@aaccioly I'll take a look if it repros in our latest build of the Visual C++ debugger bits.

[aaccioly]

Hi @pieandcakes, brilliant. Unfortunately I don't have access to VS Studio 2017 or insiders build.

Anyway, debugging works with VS 2015 Update 3:

1. devenv.exe /debugexe output\hello.exe
2. New Function Breakpoint (Ctrl+B). Function name main
3. Start Debugging (F5)
4. Step Over 4 times (F10)

Joy.

I've also noticed that VS 2015 download way more PDBs than Visual Studio Code

[pieandcakes]

@aaccioly AFAIK we don't have symbol server support in VSCode. Symbols would need to be provided locally. If you need symbol server support, our recommendation is to use Visual Studio itself.

[aaccioly]

@pieandcakes Fair enough. Symbol servers are actually a completely new concept to me. I've only played with it to to try the troubleshoot the issue (just wondering it the lack of symbols was getting in the way). Besides, there is a symbolsSearchPath option in vscode. Can we make it work with the syntax that I've passed to _NT_SYMBOL_PATH? (I know, separate issue all together, but certainly useful).

[pieandcakes]

@aaccioly It looks like it just hangs with 0.12.0 on my machine. I tested it with the update that will be coming out this week and it works. Please wait for the update and let me know if that works.

We currently don't support _NT_SYMBOL_PATH and I can add it to the backlog of work items.

[aaccioly]

Hi @pieandcakes, brilliant. As soon as I get an opportunity to test it I'll let you know.

[aaccioly]

Hi @pieandcakes, unfortunately it is still not working for me after updating to version 0.12.1.

Debug logs

-------------------------------------------------------------------
You may only use the C/C++ Extension for Visual Studio Code with
Visual Studio Code, Visual Studio or Visual Studio for Mac software
to help you develop and test your applications.
-------------------------------------------------------------------
Loaded 'C:\Users\N662831\Documents\Projects\C-C++\test-vscode\output\hello.exe'. Symbols loaded.
Loaded 'C:\Windows\System32\ntdll.dll'. Symbols loaded.
Loaded 'C:\Windows\System32\kernel32.dll'. Symbols loaded.
Loaded 'C:\Windows\System32\KernelBase.dll'. Symbols loaded.
Loaded 'C:\Windows\System32\sysfer.dll'. Cannot find or open the PDB file.
Loaded 'C:\Windows\System32\advapi32.dll'. Symbols loaded.
Loaded 'C:\Windows\System32\msvcrt.dll'. Symbols loaded.
Loaded 'C:\Windows\System32\sechost.dll'. Symbols loaded.
Loaded 'C:\Windows\System32\rpcrt4.dll'. Cannot find or open the PDB file.
Exception thrown at 0x000007FEFD64A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000002AD930.
Exception thrown at 0x000007FEFD64A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000002AD930.
Exception thrown at 0x000007FEFD64A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000002AD930.
Exception thrown at 0x000007FEFD64A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000002AD930.
Exception thrown at 0x000007FEFD64A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000002AD930.
Exception thrown at 0x000007FEFD64A06D in hello.exe: Microsoft C++ exception: SysferException at memory location 0x00000000002AD930.
Loaded 'C:\Windows\System32\psapi.dll'. Symbols loaded.
Loaded 'C:\Windows\System32\api-ms-win-core-synch-l1-2-0.dll'. Module was built without symbols.
Unloaded 'C:\Windows\System32\api-ms-win-core-synch-l1-2-0.dll'.
Loaded 'C:\Windows\System32\api-ms-win-core-synch-l1-2-0.dll'. Symbols loaded.
Loaded 'C:\Windows\System32\privman64.dll'. Cannot find or open the PDB file.
Exception thrown at 0x0000000077792525 (ntdll.dll) in hello.exe: 0xC0000005: Access violation writing location 0x0000000000000000.

[pieandcakes]

@aaccioly Sorry I've been on vacation. I'll take a look today/tomorrow and see if I can duplicate this.

[pieandcakes]

@aaccioly Can you tell me if you are running x86 or x64 Windows 7 Enterprise?

[pieandcakes]

So this is what I tried.

• I installed Windows 7 Enterprise with SP1 x64
• I downloaded the latest VS Code version 1.15.1.
• I downloaded the newest C/C++ extension version 0.12.3
• I downloaded the Visual C++ build tools 2015 version

I copied out all your files and then ran the build_cl task.
I then ran the (Windows) Launch configuration after setting the function breakpoint at main. I pressed F10 4 times and I didn't see any issues.

I don't know what is different in your configuration but I can't seem to duplicate the issue.

[aaccioly]

Hi @pieandcakes. I'm running x64. Looks like we are using the exact same versions.

Some things that I've noticed:

1. I'm getting some exceptions even before the std::cout line. Your debug logs looks way cleaner than mine.
2. When the debugger works it loads a second tab containing helloworld.cpp (check the first screenshot)
3. After it fails or if I hit Stop (Shift+F5) both tabs are left often.
4. Then if I try to debug again the debugger fails to stop at the breakpoint. Debug logs are exactly like cppvsdbg can't step over Standard Library calls #879 (comment)
5. After that I can't launch the debugger in a reliable way anymore. Sometimes vscode stops at the breakpoint, but often it doesn't.

[aaccioly]

After a failure the Call Stack looks interesting. I don't even have an f drive mapped :D