Delve: Unreadable arguments and "debugging optimized function" warning

[antoineco]

Environment

dlv 1.1.0 (master @ 4e4ed029)
go 1.11.1
os darwin/amd64

What did you do?

With the following test code:

https://gist.github.com/antoineco/262c7dc7860ddd25ef5cd124d2a8ceb3

I ran:

$ dlv test ./
Type 'help' for list of commands.

(dlv) b k8s.io/client-go/testing.(*tracker).add
Breakpoint 1 set at 0x19ec06b for issue/vendor/k8s.io/client-go/testing.(*tracker).add() ./vendor/k8s.io/client-go/testing/fixture.go:309



md5-e1499672e4c4d18dafc7385e3e5d5e50

(dlv) args

**What did you expect to see?**

The `args` command prints the value of the function arguments.

**What did you see instead?**

`Warning: debugging optimized function` is printed and function arguments are unreadable.

```gdb
(dlv) args
gvr = (unreadable empty OP stack)
ns = (unreadable could not find loclist entry at 0x4bed3 for address 0x1e3050b)
obj = (unreadable could not find loclist entry at 0x4bf0f for address 0x1e3050b)
replaceExisting = (unreadable could not find loclist entry at 0x4bf4a for address 0x1e3050b)
t = (unreadable could not find loclist entry at 0x4bf7f for address 0x1e3050b)
~r4 = (unreadable empty OP stack)

Important note

⚠️ Here comes the interesting part.

If one un-comments the commented out lines inside issue.go, the warning will not appear, and Delve will consistently print function arguments:

(dlv) args
gvr = issue/vendor/k8s.io/apimachinery/pkg/runtime/schema.GroupVersionResource {Group: "", Version: "v1", Resource: "events"}
ns = ""
obj = issue/vendor/k8s.io/apimachinery/pkg/runtime.Object(*issue/vendor/k8s.io/api/core/v1.Event) 0xc0000f8dd8
replaceExisting = false
t = (*issue/vendor/k8s.io/client-go/testing.tracker)(0xc0002c5400)
~r4 = (unreadable invalid interface type: could not find str field)

[aarzilli]

Duplicate of https://github.com/golang/go/issues/27681

[barbu110]

it still happens to me after golang/go#27681 has been closed

[j0hnwhyte]

Same, using the integrated debugger of Goland. The binary is built without optimization, and not all variables are readable.

Using the build flags (go 1.12):
go build -o=/... -gcflags="all=-N -l" ...

Error:
unreadable: could not find loclist entry at 0x... for address 0x...