why could not show some variable when debuging the go program?

[jiebanghan]

The result is below:

github.com/ethereum/go-ethereum/internal/ethapi.(*PublicDebugAPI).PrintBlock() ./mychain/go-ethereum/build/_workspace/src/github.com/ethereum/go-ethereum/build/_workspace/src/github.com/ethereum/go-ethereum/internal/ethapi/api.go:1392 (PC: 0xafc5e1)
1387: return fmt.Sprintf("%x", encoded), nil
1388: }
1389:
1390: // PrintBlock retrieves a block and returns its pretty printed form.
1391: func (api *PublicDebugAPI) PrintBlock(ctx context.Context, number uint64) (string, error) {
=>1392: block, _ := api.b.BlockByNumber(ctx, rpc.BlockNumber(number))
1393: if block == nil {
1394: return "", fmt.Errorf("block #%d not found", number)
1395: }
1396: return fmt.Sprintf("%s", block), nil
1397: }
(dlv) p block
Command failed: could not find symbol value for block
(dlv)

So please tell me how to show block? is there some setting in Makefile in order to debug it?

[aarzilli]

The reason is almost certainly that the compiler optimized away or registerized the block variable. You will have to compile with optimizations disabled (go build -gcflags '-N -l'), see also golang/go#19340

[jiebanghan]

thank you very much

[jiebanghan]

befor modifing The Makefile is below:
GOBIN = build/bin
GO ?= latest

geth:
build/env.sh go run build/ci.go install ./cmd/geth
@echo "Done building."
@echo "Run "$(GOBIN)/geth" to launch geth."

after modification below:

GOBIN = build/bin
GO ?= latest

geth:
build/env.sh go run -gcflags='-N -l' build/ci.go install ./cmd/geth
@echo "Done building."
@echo "Run "$(GOBIN)/geth" to launch geth."

i modified the Makefile above, but the error is the same. could not see the variable

1364: }
1365:
1366: // PrintBlock retrieves a block and returns its pretty printed form.
1367: func (api *PublicDebugAPI) PrintBlock(ctx context.Context, number uint64) (string, error) {
1368: block, _ := api.b.BlockByNumber(ctx, rpc.BlockNumber(number))
=>1369: if block == nil {
1370: return "", fmt.Errorf("block #%d not found", number)
1371: }
1372: return fmt.Sprintf("%s", block), nil
1373: }
1374:
(dlv) p block
Command failed: could not find symbol value for block
(dlv) p block
Command failed: could not find symbol value for block

[aarzilli]

You should ask the ethereum project, I don't know.

[jiebanghan]

Ok, thank you very much

[derekparker]

@jiebanghan it looks like from your example you're adding the compiler flags to the go run step instead of the go install step, maybe try that instead and see if it works.