I was trying to debug a Go package with lots of dependencies, trying to trace function calls across dependencies to get to the bottom of a bug.
Delve – via both CLI and VSCode GUI debugger – followed function calls to a certain depth, but then suddenly refused to go any deeper and instead of allowing me to access the local variables in that function call, produced a cryptic <autogenerated>:1 (PC: 0x141e850).
On VSCode I get this error instead: go list failed on .: can't load package: package .: no Go files in C:\Program Files\Microsoft VS Code
I know this is kind of vague, but can anybody point me to what this might mean?
This might answer your doubt: Github: go-delve/delve #1908
Read the full thread.
For anyone who runs into this in the future:
The solution is to set breakpoints IN the functions that are getting called as well. I tried this, and it does in fact follow the function calls properly.
Related
I am starting to learn Go following this Microsoft tutorial. The program runs and displays the result as in the tutorial, but the two problems that it is marking me cause me concern. I do not want to continue without understanding what this detail is due to, someone who has also happened to it, or who helps me to know what it is due to, I will be very grateful.
package main
import (
"fmt"
"github.com/x0z38/calculator"
"rsc.io/quote"
)
func main(){
total := calculator.Sum(3, 5)
fmt.Println(total)
fmt.Println("Version: ", calculator.Version)
fmt.Println(quote.Hello())
}
I leave you the image where the error is marked in red lines in the editor:
I leave the image of the two problems:
According to what I understood is that it does not find those files in any of the mentioned paths, but both files if I have them inside this path: C:\Projects\Go\src.
My GOPATH environment variable is: C:\Projects\Go
Golang has two ways to manage dependencies: old and new. Switching between them is usually done automatically.
Visual Sudio Code tries to check for dependencies using the old way. But I see you have go.mod and go.sum files which means you are using the new way (the Golang module system).
The environment variable GO111MODULE is used to switch between dependency control modes. It has 3 values: auto, on, off. The default is auto.
What you see is just a syntax highlighting problem and not a compilation or execution error.
What I have learned is that you want VS Code (or gopls) to correctly identify a multi-module project. Please refer to this (your are using Go1.18).
And more about go modules.
And go workspace.
Hope those can help you.
Ok this is what I did:
First: Run go mod tidy as suggested by Mushroomator in my root project, and it didn't work
Second: remove the GOPATH environment variable, since as JimB commented it is no longer used, and it didn't work either.
Now, this is where I feel a bit confused, because maybe I did what they asked me to do but I don't know how to explain it.
So, it works and no longer shows a syntax error. Delete the GOPATH environment variable, SET GOMODULE111=on, and take out the Projects/Go directory where I have all the files and put it on the desktop and mark this syntax error:
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Now, as you can see, I open VS Code directly in the helloworld directory, and the syntax error disappears, but I wanted to have it open directly from the src directory to see everything I've learned so far:
I'm building AOSP from source and have created a small C++ program that prints some messages to logcat when started. Now I wanted to debug the program according to https://source.android.com/devices/tech/debug/gdb
In the reference you're encouraged to use lldb in favor of gdb and there is also a short section on using vs code as debugger.
However, I cannot find the mentioned script lldbclient anywhere in my source nor in Android Code Search, only gdbclient.py seems to be present.
Q1: Where can I find lldbclient script?
When running the gdbclient.py script the option --setup-forwarding vscode seems to be ignored and gdb is always started.
Q2: If there isn't a lldbclient script, what options do I have to pass to gdbclient.py to enable debugging with lldb and vs code?
What did I do so far?
gdbclient.py -r /data/mysample_bin --setup-forwarding vscode
Starts my native program with attached gdb and allows me to step through my program.
Though I do not know how to code python, I was able to track down a call sequence in the script to method generate_setup_script, which is called with parameter debugger=gdb. Therefore no lldb configuration for vs code is created. Passing --no-gdb or --lldb to the script doesn't change this behavior.
Q1: You can find lldbclient.py script in the repository https://android.googlesource.com/platform/development, branch android-s-beta-2 (or another android-s branch).
Q2: Android also provides some tutorial debugging with Vscode: https://source.android.com/devices/tech/debug/gdb#vscode.
I setup a breakpoint in my Go code with runtime.Breakpoint(), save the file (my editor, Atom with go-plus installed, runs go install . on save). Then I run Delve in terminal with dlv debug, and type continue after it starts.
When the breakpoint kicks in, I want to test a couple of things (basically to print reader's data via a bytes.Buffer). But, I get the following error
buf := new(bytes.Buffer): "1:5: expected 'EOF', found ':='"
and in general cannot do much more than print values.
Is it really not possible to do this sort of thing? I am used to Python's pdb where setting variables or calling functions is not a problem and I would expect Delve is capable of the same.
So, what am I doing wrong?
Not possible yet. Right now (2018-NOV) work is in progress on Delve, but unfinished.
Go runtime was changed recently to allow this kind of call. Delve have a Github issue tracking the progress of such feature, but is still experimental and incomplete.
Initially, I wanted to install the updated MinGW packages using the MinGW-get GUI, but it crashes when I choose "Mark All Upgrades" from the 'Installation' drop-down menu (whether I update the catalogue or not).
Now, I want to figure out why guimain.exe is crashing.
How can I diagnose and debug this persistent problem? I am vaguely familiar with GDB, but I've never used it. I am not committed to using the Visual Studio debugger.
I assume I need to use some ancillary binaries or debug libraries in the latest MinGW installer branch here: https://sourceforge.net/projects/mingw/files/Installer/mingw-get/mingw-get-0.6.2-beta-20131004-1/
Can anyone please guide me? Any assistance or suggested reading is appreciated.
For those who are experiencing the crash on attempting to upgrade packages.. try running it in recursive mode..
mingw-get upgrade --recursive
that appeared to force an upgrade for me..
I happen to have the same issue. The GDB way to debug this:
gdb mingw-get.exe
r upgrade (run with argument upgrade)
GDB will automatically stop at a SIGSEGV (Segmentation fault) signal, that's what happens for me.
bt (get a backtrace)
For me this resulted in a huge backtrace, filled with calls to:
#5013 0x6f9cdda4 in mingw-get-0!_ZN14pkgXmlDocument19ResolveDependenciesEP10pkgXmlNodeP13pkgActionItem () from c:\MinGW\libexec\mingw-get\mingw-get-0.dll
It looks like a recursion problem that quickly filled up the call stack.
Note that function name is mangled, and we don't know the line number. This is the best you can do without debugging symbols. If you have the debugging symbols, GDBs output becomes more useful. For most Linux-style packages, you can get the debugging symbols in a -dbg package named similiarly to the stripped binary package. However I don't see a debug package for mingw32-mingw-get in the listing.
The interactive environment is VERY helpful for a programmer. However, it seems Go does not provide it. Is my understanding correct?
No, Go does not provide a REPL(read–eval–print loop).
However, as already mentioned, Go Playground is very handy. The Go Authors are also thinking about adding a feature-rich editor to it.
If you want something local, consider installing hsandbox. Running it simply with hsandbox go will split your terminal screen (with screen) where you can write code at the top and see its execution output at the bottom on every save.
There was a gotry among standard Go commands, which used to evaluate expressions (with an optional package name), and could be run like gotry 1+2 and gotry fmt 'Println("hello")' from shell. It is no longer available because not many people actually used it.
I have also seen third party projects for building a REPL for Go, but now I can only find links to two of them: igo and go-repl. How well do they work I don't know.
My two cents: Speed of compilation makes writing a REPL possible for Go, as it has also helped building the tools mentioned here, but the same speed makes REPL less necessary. Every time I want to test something in Go that I can't run in Playground I open a simple .go file and start coding and simply run the code. This will be even easier when the go command in Go 1 makes one-command build process possible and way easier.
UPDATE: Latest weekly release of Go added go command which can be used to very easily build a file: write your prog.go file and run go build prog.go && ./prog
UPDATE 2: With Go 1 you can directly run go programs with go run filename.go
UPDATE 3: gore is a new project which seems interesting.
Try motemen/gore
Yet another Go REPL that works nicely. Featured with line editing,
code completion, and more.
https://github.com/motemen/gore
You also have a recent (March 2013) project called gore from Sriram Srinivasan, which can be useful:
gore is a command-line evaluator for golang code -- a REPL without a loop, if you will.
It is a replacement for the go playground, while making it much easier to interactively try out bits of code: gore automatically supplies boiler-plate code such as import and package declarations and a main function wrapper.
Also, since it runs on your own computer, no code is rejected on security grounds (unlike go playground's safe sandbox mode).
If you're a Vim user, the vim-go plugin (https://github.com/fatih/vim-go) provides a command (GoRun) to run and print the output of the current buffer. You still have to include all the boilerplate code of a main Go file, but it still provides a convenient way to quickly test code snippets in your local environment.
Have you tried the Go Playground?
About the Go Playground
The Go Playground is a web service that runs on golang.org's servers.
The service receives a Go program, compiles, links, and runs the
program inside a sandbox, then returns the output.
The GoSpeccy project includes a builtin REPL of a restricted subset of the Go language. The implementation is using goeval.
No, but you can exploit the speed of compilation (as mentioned in other answers).
Have a look at rango that uses a generate-compile-run loop to mimic a REPL. You can also start it with imports and statements to begin an interactive session.
Gosh is the interactive Golang shell. The goal is to provide an easy-to-use interactive execution environment.
https://github.com/mkouhei/gosh
I've had some luck with the VSCode debugger, but it's fairly limited in so far as you cannot invoke function calls from the debug console Debug: Function Calls not supported #2225.
Basically you set a breakpoint after properly configuring your launch.json file. Then you can drill down on the left in the variables side bar and enter variable expressions an the debug console.
You may also like to try https://github.com/haya14busa/goplay
This enables you to run go code files from your terminal directly to the Go Playground
Please also check www.gorepl.com for go REPL and other REPLs
Go code can be run in a REPL-like way in Visual Studio Code with the Go extension and Code Runner extension. Click the Run triangle ▶ which is marked by the mouse cursor in the below screenshot to run the code and show the results in the Output pane at the bottom of Visual Studio Code.
When programming with Go Visual Studio Code will suggest additional Go extensions that can be installed to extend Visual Studio Code's functionality.