From af91f350176871de853df76a4222ba350edce71c Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Tue, 15 Jul 2025 17:13:10 +0200
Subject: [PATCH] Fix stringify of $vaexpr #2301.

---
 releasenotes.md                               |  1 +
 src/compiler/parse_expr.c                     |  2 +-
 src/compiler/sema_expr.c                      | 29 ++++++++----
 .../compile_time/stringify_vaexp.c3t          | 47 +++++++++++++++++++
 4 files changed, 70 insertions(+), 9 deletions(-)
 create mode 100644 test/test_suite/compile_time/stringify_vaexp.c3t

diff --git a/releasenotes.md b/releasenotes.md
index 08fdc93cd..3abee118c 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -51,6 +51,7 @@
 - Fixed bug splatting constants into constants.
 - Resize bug when resizing memory down in ArenaAllocator, DynamicArenaAllocator, BackedArenaAllocator.
 - Error message for missing arg incorrect for methods with zero args #2296.
+- Fix stringify of $vaexpr #2301.
 
 ### Stdlib changes
 - Improve contract for readline. #2280
diff --git a/src/compiler/parse_expr.c b/src/compiler/parse_expr.c
index a7144454c..0a580a1db 100644
--- a/src/compiler/parse_expr.c
+++ b/src/compiler/parse_expr.c
@@ -659,7 +659,7 @@ static Expr *parse_ct_stringify(ParseContext *c, Expr *left, SourceSpan lhs_star
 	ASSIGN_EXPR_OR_RET(Expr *inner, parse_expr(c), poisoned_expr);
 	const char *end = c->lexer.lexing_start - 1;
 	CONSUME_OR_RET(TOKEN_RPAREN, poisoned_expr);
-	if (inner->expr_kind == EXPR_HASH_IDENT)
+	if (inner->expr_kind == EXPR_HASH_IDENT || (inner->expr_kind == EXPR_CT_ARG && inner->ct_arg_expr.type == TOKEN_CT_VAEXPR))
 	{
 		Expr *expr = expr_new(EXPR_STRINGIFY, start_span);
 		expr->inner_expr = inner;
diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
index d2ad30c39..92524168d 100644
--- a/src/compiler/sema_expr.c
+++ b/src/compiler/sema_expr.c
@@ -10591,18 +10591,31 @@ static inline bool sema_expr_analyse_ct_stringify(SemaContext *context, Expr *ex
 {
 	Expr *inner = expr->inner_expr;
 	// Only hash ident style stringify reaches here.
-	ASSERT_SPAN(expr, inner->expr_kind == EXPR_HASH_IDENT);
 	while (true)
 	{
-		Decl *decl = sema_resolve_symbol(context, inner->ct_ident_expr.identifier, NULL, inner->span);
-		if (!decl) return false;
-		inner = decl->var.init_expr;
-		while (inner->expr_kind == EXPR_OTHER_CONTEXT)
+		switch (inner->expr_kind)
 		{
-			context = inner->expr_other_context.context;
-			inner = inner->expr_other_context.inner;
+			case EXPR_CT_ARG:
+			{
+				ASSIGN_EXPR_OR_RET(Expr *arg_expr, sema_expr_analyse_ct_arg_index(context, exprptr(inner->ct_arg_expr.arg), NULL), false);
+				inner = arg_expr;
+				continue;
+			}
+			case EXPR_OTHER_CONTEXT:
+				context = inner->expr_other_context.context;
+				inner = inner->expr_other_context.inner;
+				continue;
+			case EXPR_HASH_IDENT:
+			{
+				Decl *decl = sema_resolve_symbol(context, inner->ct_ident_expr.identifier, NULL, inner->span);
+				if (!decl) return false;
+				inner = decl->var.init_expr;
+				continue;
+			}
+			default:
+				break;
 		}
-		if (inner->expr_kind != EXPR_HASH_IDENT) break;
+		break;
 	}
 	const char *desc = span_to_string(inner->span);
 	if (!desc)
diff --git a/test/test_suite/compile_time/stringify_vaexp.c3t b/test/test_suite/compile_time/stringify_vaexp.c3t
new file mode 100644
index 000000000..41ee4b04a
--- /dev/null
+++ b/test/test_suite/compile_time/stringify_vaexp.c3t
@@ -0,0 +1,47 @@
+// #target: macos-x64
+module test;
+import std::io;
+
+fn int main(String[] args)
+{
+	String a = @foo1(args);
+    String b = @foo2(args);
+    String c = @foo3(args);
+  return 0;
+}
+
+macro @foo1(#expr)
+{
+	return $stringify(#expr);
+}
+
+macro @foo2(...)
+{
+	return $stringify($vaexpr[0]);
+}
+
+macro @foo3(#expr)
+{
+	return @foo2(#expr);
+}
+
+/* #expect: test.ll
+
+@.str = private unnamed_addr constant [5 x i8] c"args\00", align 1
+@.str.1 = private unnamed_addr constant [5 x i8] c"args\00", align 1
+@.str.2 = private unnamed_addr constant [5 x i8] c"args\00", align 1
+
+define i32 @test.main(ptr %0, i64 %1) #0 {
+entry:
+  %args = alloca %"char[][]", align 8
+  %a = alloca %"char[]", align 8
+  %b = alloca %"char[]", align 8
+  %c = alloca %"char[]", align 8
+  store ptr %0, ptr %args, align 8
+  %ptradd = getelementptr inbounds i8, ptr %args, i64 8
+  store i64 %1, ptr %ptradd, align 8
+  store %"char[]" { ptr @.str, i64 4 }, ptr %a, align 8
+  store %"char[]" { ptr @.str.1, i64 4 }, ptr %b, align 8
+  store %"char[]" { ptr @.str.2, i64 4 }, ptr %c, align 8
+  ret i32 0
+}