// valPos tries to find a position for the given value
// even if the value doesn't have one.
func valPos(val ssa.Value) token.Pos {
if pos := val.Pos(); pos.IsValid() {
return pos
}
instr, ok := val.(ssa.Instruction)
if !ok {
return token.NoPos
}
for _, op := range instr.Operands(nil) {
if pos := (*op).Pos(); pos.IsValid() {
return pos
}
}
return token.NoPos
}
func (ctxt *context) getErrorInfo(v ssa.Value, member int, enclosingPos token.Pos, seen map[ssa.Value]bool) (result *errorInfo) {
if !enclosingPos.IsValid() {
panicf("getErrorInfo with invalid pos; %T %s", v, v)
}
// log.Printf("getErrorInfo[%d] %T %v {", member, v, v)
// defer func() {
// log.Printf("} -> %+v", result)
// }()
if seen[v] {
return &errorInfo{}
}
seen[v] = true
defer delete(seen, v)
if pos := v.Pos(); pos.IsValid() {
enclosingPos = pos
}
terminate := func() []errorTermination {
return []errorTermination{{
val: v,
pos: enclosingPos,
}}
}
switch v := v.(type) {
case *ssa.Call:
if member > 0 && member != v.Type().(*types.Tuple).Len()-1 {
log.Printf("error from non-final member of function")
return &errorInfo{unknown: terminate()}
}
return &errorInfo{nested: []*ssa.Call{v}}
case *ssa.ChangeInterface:
return ctxt.getErrorInfo(v.X, 0, enclosingPos, seen)
case *ssa.Extract:
return ctxt.getErrorInfo(v.Tuple, v.Index, enclosingPos, seen)
case *ssa.Field:
return &errorInfo{unknown: terminate()}
case *ssa.Index:
return &errorInfo{unknown: terminate()}
case *ssa.Lookup:
return &errorInfo{unknown: terminate()}
case *ssa.Const:
if v.Value != nil {
panicf("non-nil constant cannot make error, surely?")
}
return &errorInfo{}
case *ssa.MakeInterface:
// TODO look into components of v.X
return &errorInfo{nonNil: terminate()}
case *ssa.Next:
return &errorInfo{unknown: terminate()}
case *ssa.Parameter:
return &errorInfo{unknown: terminate()}
case *ssa.Phi:
var info errorInfo
for _, edge := range v.Edges {
info.add(ctxt.getErrorInfo(edge, member, enclosingPos, seen))
}
return &info
case *ssa.Select:
return &errorInfo{unknown: terminate()}
case *ssa.TypeAssert:
if v.CommaOk {
return &errorInfo{unknown: terminate()}
}
return ctxt.getErrorInfo(v.X, 0, enclosingPos, seen)
case *ssa.UnOp:
switch v.Op {
case token.ARROW:
return &errorInfo{unknown: terminate()}
case token.MUL:
if _, isGlobal := v.X.(*ssa.Global); isGlobal {
// Assume that if we're returning a global variable, it's a
// global non-nil error, such as os.ErrInvalid.
return &errorInfo{nonNil: terminate()}
}
return &errorInfo{unknown: terminate()}
default:
panicf("unexpected unary operator %s at %s", v, ctxt.lprog.Fset.Position(enclosingPos))
}
}
panicf("unexpected value found for error: %T; %v", v, v)
panic("not reached")
}