ability to cast explicitly from int to enum

This commit also fixes a bug where pure functions are marked with
the read-only attribute in debug mode. This resulted in incorrect
codegen because calls to read-only functions with unused values
were not generated.

For example, a call to assert() would not be generated if assert
is marked with read-only. Which it *is* marked with in release
mode.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/codegen.cpp b/src/codegen.cpp
index b25a3b6869..43fc41bed9 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -1032,6 +1032,8 @@ static LLVMValueRef gen_cast_expr(CodeGen *g, AstNode *node) {
             set_debug_source_node(g, node);
             return LLVMBuildZExt(g->builder, expr_val, wanted_type->type_ref, "");
 
+        case CastOpIntToEnum:
+            return gen_widen_or_shorten(g, node, actual_type, wanted_type->data.enumeration.tag_type, expr_val);
     }
     zig_unreachable();
 }
@@ -3913,7 +3915,7 @@ static void do_code_gen(CodeGen *g) {
             LLVMZigAddNonNullAttr(fn_table_entry->fn_value, 1);
             is_sret = true;
         }
-        if (fn_table_entry->is_pure && !is_sret) {
+        if (fn_table_entry->is_pure && !is_sret && g->is_release_build) {
             LLVMAddFunctionAttr(fn_table_entry->fn_value, LLVMReadOnlyAttribute);
         }