Commit `34eb9f18ac`

Andrew Kelley <andrew@ziglang.org>

2019-02-10 02:41:26

fix not updating debug info type of optional error sets

There's an unfortunate footgun in the current design of error sets. The debug info type for every error set is the same as the debug info type of the global error set, which is essentially an enum forward declaration. The problem is that when we "replace" the forward declaration with the final value, once we know all the possible errors, we have to update the pointers of every error set. So the footgun is that if you ever copy the debug info type of the global error set, you have to add the address of the pointer to a list of pointers that need to be updated once we "replace" the forward declaration. I activated the footgun when I introduced the optimization that `?anyerror` types are the same size as `anyerror` types (using 0 as the null value), because I introduced a pointer copy of the global error set debug info type, but forgot to add it to the list. I'm sure that there is a better way to code this, which does not have the footgun, but this commit contains only a fix, not a reworking of the logic. closes #1937

master

1 parent ca8580e

Changed files (2)

src

analyze.cpp

test

stage1

behavior

error.zig

@@ -594,6 +594,9 @@ ZigType *get_optional_type(CodeGen *g, ZigType *child_type) {
             // function types are technically pointers
             entry->type_ref = child_type->type_ref;
             entry->di_type = child_type->di_type;
+            if (entry->di_type == g->builtin_types.entry_global_error_set->di_type) {
+                g->error_di_types.append(&entry->di_type);
+            }
         } else {
             assert(child_type->di_type);
             // create a struct with a boolean whether this is the null value

@@ -330,3 +330,8 @@ test "optional error set is the same size as error set" {
     expect(S.returnsOptErrSet() == null);
     comptime expect(S.returnsOptErrSet() == null);
 }
+
+test "debug info for optional error set" {
+    const SomeError = error{Hello};
+    var a_local_variable: ?SomeError = null;
+}

Commit 34eb9f18ac

Commit `34eb9f18ac`