fix `@tagName` on extern and non-exhaustive enums

1 files changed, 11 insertions, 6 deletions

diff --git a/src/codegen.cpp b/src/codegen.cpp
index f9d2566da7..0bf8510843 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -5031,8 +5031,18 @@ static LLVMValueRef get_enum_tag_name_function(CodeGen *g, ZigType *enum_type) {
         LLVMConstNull(usize->llvm_type),
     };
 
+    HashMap<BigInt, Buf *, bigint_hash, bigint_eql> occupied_tag_values = {};
+    occupied_tag_values.init(field_count);
+
     for (size_t field_i = 0; field_i < field_count; field_i += 1) {
-        Buf *name = enum_type->data.enumeration.fields[field_i].name;
+        TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[field_i];
+        
+        Buf *name = type_enum_field->name;
+        auto entry = occupied_tag_values.put_unique(type_enum_field->value, name);
+        if (entry != nullptr) {
+            continue;
+        }
+
         LLVMValueRef str_init = LLVMConstString(buf_ptr(name), (unsigned)buf_len(name), true);
         LLVMValueRef str_global = LLVMAddGlobal(g->module, LLVMTypeOf(str_init), "");
         LLVMSetInitializer(str_global, str_init);
@@ -5086,11 +5096,6 @@ static LLVMValueRef ir_render_enum_tag_name(CodeGen *g, IrExecutableGen *executa
 {
     ZigType *enum_type = instruction->target->value->type;
     assert(enum_type->id == ZigTypeIdEnum);
-    if (enum_type->data.enumeration.non_exhaustive) {
-        add_node_error(g, instruction->base.base.source_node,
-            buf_sprintf("TODO @tagName on non-exhaustive enum https://github.com/ziglang/zig/issues/3991"));
-        codegen_report_errors_and_exit(g);
-    }
 
     LLVMValueRef enum_name_function = get_enum_tag_name_function(g, enum_type);