disable field access for unknown length pointers

See #770

Author: andrewrk

src/analyze.cpp

@@ -3753,13 +3753,13 @@ static bool is_container(TypeTableEntry *type_entry) {
 }
 
 bool is_container_ref(TypeTableEntry *type_entry) {
-    return (type_entry->id == TypeTableEntryIdPointer) ?
+    return (type_entry->id == TypeTableEntryIdPointer && type_entry->data.pointer.ptr_len == PtrLenSingle) ?
         is_container(type_entry->data.pointer.child_type) : is_container(type_entry);
 }
 
 TypeTableEntry *container_ref_type(TypeTableEntry *type_entry) {
     assert(is_container_ref(type_entry));
-    return (type_entry->id == TypeTableEntryIdPointer) ?
+    return (type_entry->id == TypeTableEntryIdPointer && type_entry->data.pointer.ptr_len == PtrLenSingle) ?
         type_entry->data.pointer.child_type : type_entry;
 }
 

test/compile_errors.zig

@@ -1,6 +1,19 @@
 const tests = @import("tests.zig");
 
 pub fn addCases(cases: *tests.CompileErrorContext) void {
+    cases.add(
+        "field access of unknown length pointer",
+        \\const Foo = extern struct {
+        \\    a: i32,
+        \\};
+        \\
+        \\export fn entry(foo: [*]Foo) void {
+        \\    foo.a += 1;
+        \\}
+    ,
+        ".tmp_source.zig:6:8: error: type '[*]Foo' does not support field access",
+    );
+
     cases.add(
         "unknown length pointer to opaque",
         \\export const T = [*]@OpaqueType();