From 4a3a7a92cbfcdcfd33826fd4a2e9e593b48e77f2 Mon Sep 17 00:00:00 2001
From: Louis Novy <101842021+louisnovy@users.noreply.github.com>
Date: Fri, 2 Oct 2026 09:18:30 -0400
Subject: [PATCH] Fix the length of fixed capacity dynamic array literals whose
 elements can't be constant

---
 src/llvm_backend_expr.cpp         |  7 +++++--
 tests/issues/run.bat              |  1 +
 tests/issues/run.sh               |  1 +
 tests/issues/test_issue_7430.odin | 13 +++++++++++++
 4 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 tests/issues/test_issue_7430.odin

diff --git a/src/llvm_backend_expr.cpp b/src/llvm_backend_expr.cpp
index 0e90d8d74..cfa31344c 100644
--- a/src/llvm_backend_expr.cpp
+++ b/src/llvm_backend_expr.cpp
@@ -6458,13 +6458,16 @@ gb_internal lbAddr lb_build_addr_compound_lit(lbProcedure *p, Ast *expr) {
 
 	case Type_FixedCapacityDynamicArray: {
 		if (cl->elems.count > 0) {
-			lb_addr_store(p, v, lb_const_value(p->module, type, exact_value_compound(expr)));
+			// NOTE: the length isn't taken from the literal's constant, which is nil when its elements can't be constant
+			lbValue dst_ptr = lb_addr_get_ptr(p, v);
+			lbValue value = lb_const_value(p->module, type, exact_value_compound(expr));
+			lb_emit_store(p, lb_emit_struct_ep(p, dst_ptr, 0), lb_emit_struct_ev(p, value, 0));
+			lb_emit_store(p, lb_emit_struct_ep(p, dst_ptr, 1), lb_const_int(p->module, t_int, cl->max_count));
 
 			auto temp_data = array_make<lbCompoundLitElemTempData>(temporary_allocator(), 0, cl->elems.count);
 
 			lb_build_addr_compound_lit_populate(p, cl->elems, &temp_data, type);
 
-			lbValue dst_ptr = lb_addr_get_ptr(p, v);
 			for_array(i, temp_data) {
 				i32 index = cast(i32)(temp_data[i].elem_index);
 				temp_data[i].gep = lb_emit_array_epi(p, dst_ptr, index);
diff --git a/tests/issues/run.bat b/tests/issues/run.bat
index 5c92eb840..a276b04a7 100644
--- a/tests/issues/run.bat
+++ b/tests/issues/run.bat
@@ -59,6 +59,7 @@ set COMMON=-define:ODIN_TEST_FANCY=false -file -vet -strict-style -ignore-unused
 ..\..\..\odin build ..\test_issue_7037.odin %COMMON% -o:none  || exit /b
 ..\..\..\odin test ..\test_issue_7421.odin %COMMON% || exit /b
 ..\..\..\odin check ..\test_issue_7421_tagged_duplicate.odin %COMMON% 2>&1 | find /c "Error: Duplicate case" | findstr /x "1" || exit /b
+..\..\..\odin test ..\test_issue_7430.odin %COMMON%  || exit /b
 ..\..\..\odin build ..\test_issue_7188.odin %COMMON%  || exit /b
 clang -c ..\test_issue_sysv_abi.c -o test_issue_sysv_abi_c.o || exit /b
 ..\..\..\odin test ..\test_issue_sysv_abi.odin %COMMON%  || exit /b
diff --git a/tests/issues/run.sh b/tests/issues/run.sh
index 22b84524f..53c4aa855 100755
--- a/tests/issues/run.sh
+++ b/tests/issues/run.sh
@@ -112,6 +112,7 @@ else
 	exit 1
 fi
 $ODIN check ../test_issue_7429.odin $COMMON_CHECK
+$ODIN test ../test_issue_7430.odin $COMMON
 $ODIN test ../test_issue_7356.odin $COMMON
 $ODIN test ../test_issue_7336.odin $COMMON
 $ODIN build ../test_issue_7167.odin $COMMON
diff --git a/tests/issues/test_issue_7430.odin b/tests/issues/test_issue_7430.odin
new file mode 100644
index 000000000..edf248356
--- /dev/null
+++ b/tests/issues/test_issue_7430.odin
@@ -0,0 +1,13 @@
+// Tests issue #7430 https://github.com/odin-lang/Odin/issues/7430
+package test_issues
+
+import "core:testing"
+
+@(test)
+test_issue_7430 :: proc(t: ^testing.T) {
+	U :: union {T}
+	T :: struct {_: []i32}
+
+	u := [dynamic; 4]U{T{}}
+	testing.expect_value(t, len(u), 1)
+}