From 02eea15b92745cd10c325722236cc9e4f420bb71 Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Thu, 6 Mar 2025 10:02:49 +0000
Subject: [PATCH] Add `Did you mean` for wrong `case`/type-assert type.

---
 src/check_expr.cpp        | 14 ++++++++++++++
 src/check_stmt.cpp        | 14 ++++++++++++++
 src/llvm_backend_type.cpp | 15 ++++-----------
 3 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 2f7b5fd0a..cf57b8c83 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -10410,6 +10410,8 @@ gb_internal ExprKind check_type_assertion(CheckerContext *c, Operand *o, Ast *no
 			}
 
 			if (!ok) {
+				ERROR_BLOCK();
+
 				gbString expr_str = expr_to_string(o->expr);
 				gbString dst_type_str = type_to_string(t);
 				defer (gb_string_free(expr_str));
@@ -10418,6 +10420,18 @@ gb_internal ExprKind check_type_assertion(CheckerContext *c, Operand *o, Ast *no
 					error(o->expr, "Cannot type assert '%s' to '%s' as this is an empty union", expr_str, dst_type_str);
 				} else {
 					error(o->expr, "Cannot type assert '%s' to '%s' as it is not a variant of that union", expr_str, dst_type_str);
+
+					for (Type *vt : bsrc->Union.variants) {
+						Type *xt = type_deref(vt);
+						Type *yt = type_deref(t);
+						if (are_types_identical(xt, yt)) {
+							gbString s = type_to_string(vt);
+							error_line("\tDid you mean: '%s'?", s);
+							gb_string_free(s);
+							break;
+						}
+					}
+
 				}
 				o->mode = Addressing_Invalid;
 				o->expr = node;
diff --git a/src/check_stmt.cpp b/src/check_stmt.cpp
index e81996566..ae7168661 100644
--- a/src/check_stmt.cpp
+++ b/src/check_stmt.cpp
@@ -1501,9 +1501,23 @@ gb_internal void check_type_switch_stmt(CheckerContext *ctx, Ast *node, u32 mod_
 						}
 					}
 					if (!tag_type_found) {
+						ERROR_BLOCK();
+
 						gbString type_str = type_to_string(y.type);
 						error(y.expr, "Unknown variant type, got '%s'", type_str);
 						gb_string_free(type_str);
+
+						for (Type *vt : bt->Union.variants) {
+							Type *xt = type_deref(vt);
+							Type *yt = type_deref(y.type);
+							if (are_types_identical(xt, yt)) {
+								gbString s = type_to_string(vt);
+								error_line("\tDid you mean: '%s'?", s);
+								gb_string_free(s);
+								break;
+							}
+						}
+
 						continue;
 					}
 					case_type = y.type;
diff --git a/src/llvm_backend_type.cpp b/src/llvm_backend_type.cpp
index 62e30a1b6..49aca89e7 100644
--- a/src/llvm_backend_type.cpp
+++ b/src/llvm_backend_type.cpp
@@ -856,17 +856,10 @@ gb_internal void lb_setup_type_info_data_giant_array(lbModule *m, i64 global_typ
 		small_const_values[1] = LLVMConstInt(lb_type(m, t_int), align, true);
 		small_const_values[2] = type_info_flags.value;
 
-		unsigned variant_index = 0;
-		if (build_context.ptr_size == 8) {
-			LLVMTypeRef base_type_info_type = LLVMStructGetTypeAtIndex(stype, 0);
-			small_const_values[3] = LLVMConstNull(LLVMStructGetTypeAtIndex(base_type_info_type, 3));
-			small_const_values[4] = id.value;
-			variant_index = 5;
-		} else {
-			small_const_values[3] = id.value;
-			variant_index = 4;
-		}
-
+		unsigned variant_index = 5;
+		LLVMTypeRef base_type_info_type = LLVMStructGetTypeAtIndex(stype, 0);
+		small_const_values[3] = LLVMConstNull(LLVMStructGetTypeAtIndex(base_type_info_type, 3));
+		small_const_values[4] = id.value;
 
 		i64 tag_index = 0;
 		if (tag_type != nullptr) {