Commit fe3ad27d5f

@@ -273,12 +273,19 @@ static void preview_function_labels(CodeGen *g, AstNode *node, FnTableEntry *fn_
 static void resolve_struct_type(CodeGen *g, ImportTableEntry *import, TypeTableEntry *struct_type) {
     assert(struct_type->id == TypeTableEntryIdStruct);
 
+    AstNode *decl_node = struct_type->data.structure.decl_node;
+
+    if (struct_type->data.structure.embedded_in_current) {
+        add_node_error(g, decl_node,
+                buf_sprintf("struct has infinite size"));
+        return;
+    }
+
     if (struct_type->data.structure.fields) {
         // we already resolved this type. skip
         return;
     }
 
-    AstNode *decl_node = struct_type->data.structure.decl_node;
 
     assert(struct_type->di_type);
 
@@ -293,6 +300,9 @@ static void resolve_struct_type(CodeGen *g, ImportTableEntry *import, TypeTableE
     uint64_t first_field_align_in_bits = 0;
     uint64_t offset_in_bits = 0;
 
+    // this field should be set to true only during the recursive calls to resolve_struct_type
+    struct_type->data.structure.embedded_in_current = true;
+
     for (int i = 0; i < field_count; i += 1) {
         AstNode *field_node = decl_node->data.struct_decl.fields.at(i);
         TypeStructField *type_struct_field = &struct_type->data.structure.fields[i];
@@ -321,6 +331,7 @@ static void resolve_struct_type(CodeGen *g, ImportTableEntry *import, TypeTableE
         offset_in_bits += type_struct_field->type_entry->size_in_bits;
 
     }
+    struct_type->data.structure.embedded_in_current = false;
 
     LLVMStructSetBody(struct_type->type_ref, element_types, field_count, false);
 

@@ -43,6 +43,9 @@ struct TypeTableEntryStruct {
     bool is_packed;
     int field_count;
     TypeStructField *fields;
+
+    // set this flag temporarily to detect infinite loops
+    bool embedded_in_current;
 };
 
 struct TypeTableEntryNumLit {

@@ -828,6 +828,16 @@ fn f() {
 }
     )SOURCE", 2, ".tmp_source.zig:3:21: error: expected type 'i32', got 'void'",
                  ".tmp_source.zig:4:15: error: incompatible types: 'i32' and 'void'");
+
+    add_compile_fail_case("direct struct loop", R"SOURCE(
+struct A { a : A, }
+    )SOURCE", 1, ".tmp_source.zig:2:1: error: struct has infinite size");
+
+    add_compile_fail_case("indirect struct loop", R"SOURCE(
+struct A { b : B, }
+struct B { c : C, }
+struct C { a : A, }
+    )SOURCE", 1, ".tmp_source.zig:2:1: error: struct has infinite size");
 }
 
 static void print_compiler_invocation(TestCase *test_case) {