Commit 7c02beb9 authored by Robert Griesemer's avatar Robert Griesemer

go/types: prevent crash in type cycles involving non-type expressions

Fixes #18643.

Change-Id: I36dca943d552a178a71094ff883b0319fe03d130
Reviewed-on: https://go-review.googlesource.com/46467
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: default avatarMatthew Dempsky <mdempsky@google.com>
parent b88efc7e
......@@ -1125,6 +1125,16 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
}
case *Array:
// Prevent crash if the array referred to is not yet set up.
// This is a stop-gap solution; a better approach would use the mechanism of
// Checker.ident (typexpr.go) using a path of types. But that would require
// passing the path everywhere (all expression-checking methods, not just
// type expression checking), and we're not set up for that (quite possibly
// an indication that cycle detection needs to be rethought). Was issue #18643.
if utyp.elem == nil {
check.error(e.Pos(), "illegal cycle in type declaration")
goto Error
}
n := check.indexedElts(e.Elts, utyp.elem, utyp.len)
// If we have an "open" [...]T array, set the length now that we know it
// and record the type for [...] (usually done by check.typExpr which is
......@@ -1135,9 +1145,21 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
}
case *Slice:
// Prevent crash if the slice referred to is not yet set up.
// See analogous comment for *Array.
if utyp.elem == nil {
check.error(e.Pos(), "illegal cycle in type declaration")
goto Error
}
check.indexedElts(e.Elts, utyp.elem, -1)
case *Map:
// Prevent crash if the map referred to is not yet set up.
// See analogous comment for *Array.
if utyp.key == nil || utyp.elem == nil {
check.error(e.Pos(), "illegal cycle in type declaration")
goto Error
}
visited := make(map[interface{}][]Type, len(e.Elts))
for _, e := range e.Elts {
kv, _ := e.(*ast.KeyValueExpr)
......
......@@ -140,4 +140,13 @@ func (*T12) m() {}
type (
P3 *T13
T13 /* ERROR cycle */ T13
)
\ No newline at end of file
)
// test cases for issue 18643
// (type cycle detection when non-type expressions are involved)
type (
T14 [len(T14 /* ERROR cycle */ {})]int
T15 [][len(T15 /* ERROR cycle */ {})]int
T16 map[[len(T16 /* ERROR cycle */ {1:2})]int]int
T17 map[int][len(T17 /* ERROR cycle */ {1:2})]int
)
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