From 0b52819090ca820d14f9441058e96c539288b1e5 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Thu, 27 Nov 2025 12:53:12 +0100
Subject: [PATCH] - Bug on rethrow in return with defer #2603.

---
 releasenotes.md                               |  1 +
 src/compiler/llvm_codegen_expr.c              |  5 ++--
 src/compiler/llvm_codegen_function.c          |  1 +
 .../statements/defer_rethrow_return.c3t       | 30 +++++++++++++++++++
 4 files changed, 35 insertions(+), 2 deletions(-)
 create mode 100644 test/test_suite/statements/defer_rethrow_return.c3t

diff --git a/releasenotes.md b/releasenotes.md
index d76791c5d..c12c93d23 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -45,6 +45,7 @@
 - `String.to_integer` does not correctly return in some cases where it should #2590.
 - Resolving a missing property on a const enum with inline, reached an assert #2597.
 - Unexpected maybe-deref subscript error with out parameter #2600.
+- Bug on rethrow in return with defer #2603.
 
 ### Stdlib changes
 - Add `CGFloat` `CGPoint` `CGSize` `CGRect` types to core_foundation (macOS).
diff --git a/src/compiler/llvm_codegen_expr.c b/src/compiler/llvm_codegen_expr.c
index 52d33bdaf..fe7210f95 100644
--- a/src/compiler/llvm_codegen_expr.c
+++ b/src/compiler/llvm_codegen_expr.c
@@ -4379,8 +4379,9 @@ static inline void llvm_emit_rethrow_expr(GenContext *c, BEValue *be_value, Expr
 	// Restore.
 	POP_CATCH();
 
+
 	// Emit success and to end.
-	llvm_emit_br(c, no_err_block);
+	bool emit_no_err = llvm_emit_br(c, no_err_block);
 
 	// Emit else
 	llvm_emit_block(c, guard_block);
@@ -4406,7 +4407,7 @@ static inline void llvm_emit_rethrow_expr(GenContext *c, BEValue *be_value, Expr
 		}
 	}
 
-	llvm_emit_block(c, no_err_block);
+	if (emit_no_err) llvm_emit_block(c, no_err_block);
 
 }
 
diff --git a/src/compiler/llvm_codegen_function.c b/src/compiler/llvm_codegen_function.c
index bace67f7b..a085d8a88 100644
--- a/src/compiler/llvm_codegen_function.c
+++ b/src/compiler/llvm_codegen_function.c
@@ -353,6 +353,7 @@ void llvm_emit_return_abi(GenContext *c, BEValue *return_value, BEValue *optiona
 	}
 	if (prototype->ret_rewrite != RET_NORMAL)
 	{
+
 		if (return_value && prototype->ret_rewrite == RET_OPTIONAL_VALUE)
 		{
 			ASSERT(return_value->value);
diff --git a/test/test_suite/statements/defer_rethrow_return.c3t b/test/test_suite/statements/defer_rethrow_return.c3t
new file mode 100644
index 000000000..bf0e7ef38
--- /dev/null
+++ b/test/test_suite/statements/defer_rethrow_return.c3t
@@ -0,0 +1,30 @@
+// #target: macos-aarch64
+module test;
+fn int main()
+{
+	foo()!!;
+	return 0;
+}
+
+fn int? foo()
+{
+	defer thing();
+	return NOT_FOUND?!;
+}
+
+fn void thing() {}
+
+/* #expect: test.ll
+
+define i64 @test.foo(ptr %0) #0 {
+entry:
+  %reterr = alloca i64, align 8
+  %error_var = alloca i64, align 8
+  store i64 ptrtoint (ptr @std.core.builtin.NOT_FOUND to i64), ptr %error_var, align 8
+  br label %guard_block
+
+guard_block:                                      ; preds = %entry
+  call void @test.thing()
+  %1 = load i64, ptr %error_var, align 8
+  ret i64 %1
+}