diff options
Diffstat (limited to 'src/cmd/compile/internal/types2/typexpr.go')
| -rw-r--r-- | src/cmd/compile/internal/types2/typexpr.go | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/types2/typexpr.go b/src/cmd/compile/internal/types2/typexpr.go index f3db3bbba93..5aacb94a605 100644 --- a/src/cmd/compile/internal/types2/typexpr.go +++ b/src/cmd/compile/internal/types2/typexpr.go @@ -428,6 +428,14 @@ func (check *Checker) instantiatedType(x syntax.Expr, targsx []syntax.Expr, def // and returns the constant length >= 0, or a value < 0 // to indicate an error (and thus an unknown length). func (check *Checker) arrayLength(e syntax.Expr) int64 { + // If e is an undeclared identifier, the array declaration might be an + // attempt at a parameterized type declaration with missing constraint. + // Provide a better error message than just "undeclared name: X". + if name, _ := e.(*syntax.Name); name != nil && check.lookup(name.Value) == nil { + check.errorf(name, "undeclared name %s for array length", name.Value) + return -1 + } + var x operand check.expr(&x, e) if x.mode != constant_ { @@ -436,6 +444,7 @@ func (check *Checker) arrayLength(e syntax.Expr) int64 { } return -1 } + if isUntyped(x.typ) || isInteger(x.typ) { if val := constant.ToInt(x.val); val.Kind() == constant.Int { if representableConst(val, check, Typ[Int], nil) { @@ -447,6 +456,7 @@ func (check *Checker) arrayLength(e syntax.Expr) int64 { } } } + check.errorf(&x, "array length %s must be integer", &x) return -1 } |