What causes "can not convert value of type %s to uint" in go-delve/delve?

Cast to the matching type: int64(...) for signed values, or convert through the variable's actual type first

can not convert value of type %s to uint

Error message

can not convert value of type %s to uint

What it means

The unsigned counterpart of error 430: Variable.asUint() loads the value and requires v.DwarfType to be an *godwarf.UintType. If the variable's DWARF type is anything else (signed int, float, string, pointer, struct...), the conversion to uint64 is rejected with this error, which includes the variable's DWARF type name.

Source

Thrown at pkg/proc/eval.go:2749

			return 0, fmt.Errorf("can not convert value of type %s to int", v.DwarfType.String())
		}
	}
	n, _ := constant.Int64Val(v.Value)
	return n, nil
}

func (v *Variable) asUint() (uint64, error) {
	if v.DwarfType == nil {
		if v.Value.Kind() != constant.Int {
			return 0, fmt.Errorf("can not convert constant %s to uint", v.Value)
		}
	} else {
		v.loadValue(loadSingleValue)
		if v.Unreadable != nil {
			return 0, v.Unreadable
		}
		if _, ok := v.DwarfType.(*godwarf.UintType); !ok {
			return 0, fmt.Errorf("can not convert value of type %s to uint", v.DwarfType.String())
		}
	}
	n, _ := constant.Uint64Val(v.Value)
	return n, nil
}

type typeConvErr struct {
	srcType, dstType godwarf.Type
}

func (err *typeConvErr) Error() string {
	return fmt.Sprintf("can not convert value of type %s to %s", err.srcType.String(), err.dstType.String())
}

func (v *Variable) isType(typ godwarf.Type, kind reflect.Kind) error {
	if v.DwarfType != nil {
		if typ == nil || !sameType(typ, v.RealType) {
			return &typeConvErr{v.DwarfType, typ}

View on GitHub (pinned to a23773e6c3)

Solutions

Cast to the matching type: int64(...) for signed values, or convert through the variable's actual type first
Use uintptr(ptr) for pointer-to-integer conversions instead of uint(ptr)
Run 'whatis <expr>' in the debugger to confirm the DWARF type before casting
If the type appears wrong, check that the binary was built with complete DWARF info

Example fix

// before
print(uint(signedVal))
// after
print(uint64(signedVal))  // or uint64(int64(signedVal)) if truncation semantics needed

Defensive patterns

Strategy: validation

Validate before calling

// check type before casting: 'whatis myVar' must report a uint* type
print(uint64(myVar))

Type guard

// only cast when DWARF type is unsigned
// if whatis(expr) matches /^uint/ then cast else use int64 or float64

Prevention

Match cast width/signedness to the variable's DWARF type
Use uintptr for pointer-to-integer conversions
Inspect variable types before writing breakpoint conditions

When it happens

Trigger: Variable.asUint() with a non-nil, non-UintType DwarfType — e.g. evaluating uint(signedIntVar), uint(floatVar), uint(ptrVar) in debugger expressions, array indexing, or internal conversion paths in eval.go.

Common situations: Casting an int or float variable to uint in a breakpoint condition; pointer-to-integer casts in watch expressions; user assumptions that 'everything numeric is convertible'.

Related errors

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/adddf6a796df2701. Report an issue: GitHub.