generic-func: fixes #1700 for generic type constraint interface nil type crash by returning err

rcoreilly · rcoreilly · commit b74e384e3f67 · 2025-06-22T13:23:14.000-07:00
diff --git a/interp/type.go b/interp/type.go
@@ -975,7 +975,8 @@ func nodeType2(interp *Interpreter, sc *scope, n *node, seen []*node) (t *itype,
 			}
 		}
 
-		if lt.incomplete {
+		if lt.incomplete { // note: per #1700 this results in a nil type with no err
+			// but TestIssue1388 for #1388 triggers this, so not changing here.
 			break
 		}
 		name := n.child[1].ident
@@ -1118,6 +1119,7 @@ func nodeType2(interp *Interpreter, sc *scope, n *node, seen []*node) (t *itype,
 
 	switch {
 	case t == nil:
+		err = n.cfgErrorf("nil type (could be trying to use a generic type constraint interface?): %s", n.kind)
 	case t.name != "" && t.path != "":
 		t.str = t.path + "." + t.name
 	case t.cat == nilT:

Original file line number	Diff line number	Diff line change
`@@ -975,7 +975,8 @@ func nodeType2(interp Interpreter, sc scope, n node, seen []node) (t *itype,`
`975`	`975`	`}`
`976`	`976`	`}`
`977`	`977`
`978`		`- if lt.incomplete {`
	`978`	`+ if lt.incomplete { // note: per #1700 this results in a nil type with no err`
	`979`	`+ // but TestIssue1388 for #1388 triggers this, so not changing here.`
`979`	`980`	`break`
`980`	`981`	`}`
`981`	`982`	`name := n.child[1].ident`
`@@ -1118,6 +1119,7 @@ func nodeType2(interp Interpreter, sc scope, n node, seen []node) (t *itype,`
`1118`	`1119`
`1119`	`1120`	`switch {`
`1120`	`1121`	`case t == nil:`
	`1122`	`+ err = n.cfgErrorf("nil type (could be trying to use a generic type constraint interface?): %s", n.kind)`
`1121`	`1123`	`case t.name != "" && t.path != "":`
`1122`	`1124`	`t.str = t.path + "." + t.name`
`1123`	`1125`	`case t.cat == nilT:`