From 36b41ce163843c9524d789e6edbc171c1d723e85 Mon Sep 17 00:00:00 2001
From: Feoramund <161657516+Feoramund@users.noreply.github.com>
Date: Thu, 5 Jun 2025 07:31:03 -0400
Subject: [PATCH] Let compound literal array be broadcast to a struct field of
 arrays

Fixes #4364

Patch courtesy of @cribalik
---
 src/llvm_backend_const.cpp        | 11 +++++++++++
 tests/issues/run.bat              |  1 +
 tests/issues/run.sh               |  1 +
 tests/issues/test_issue_4364.odin | 18 ++++++++++++++++++
 4 files changed, 31 insertions(+)
 create mode 100644 tests/issues/test_issue_4364.odin

diff --git a/src/llvm_backend_const.cpp b/src/llvm_backend_const.cpp
index 02bb7473c..e897ae282 100644
--- a/src/llvm_backend_const.cpp
+++ b/src/llvm_backend_const.cpp
@@ -1054,9 +1054,20 @@ gb_internal lbValue lb_const_value(lbModule *m, Type *type, ExactValue value, lb
 					}
 				}
 
+				res.value = lb_build_constant_array_values(m, type, elem_type, cast(isize)type->Array.count, values, cc);
+				return res;
+			} else if (value.value_compound->tav.type == elem_type) {
+				// Compound is of array item type; expand its value to all items in array.
+				LLVMValueRef* values = gb_alloc_array(temporary_allocator(), LLVMValueRef, cast(isize)type->Array.count);
+
+				for (isize i = 0; i < type->Array.count; i++) {
+					values[i] = lb_const_value(m, elem_type, value, cc).value;
+				}
+
 				res.value = lb_build_constant_array_values(m, type, elem_type, cast(isize)type->Array.count, values, cc);
 				return res;
 			} else {
+				// Assume that compound value is an array literal
 				GB_ASSERT_MSG(elem_count == type->Array.count, "%td != %td", elem_count, type->Array.count);
 
 				LLVMValueRef *values = gb_alloc_array(temporary_allocator(), LLVMValueRef, cast(isize)type->Array.count);
diff --git a/tests/issues/run.bat b/tests/issues/run.bat
index bbe9b7ca6..8e71c3f3d 100644
--- a/tests/issues/run.bat
+++ b/tests/issues/run.bat
@@ -17,6 +17,7 @@ set COMMON=-define:ODIN_TEST_FANCY=false -file -vet -strict-style
 ..\..\..\odin test ..\test_issue_2637.odin %COMMON%  || exit /b
 ..\..\..\odin test ..\test_issue_2666.odin %COMMON%  || exit /b
 ..\..\..\odin test ..\test_issue_4210.odin %COMMON%  || exit /b
+..\..\..\odin test ..\test_issue_4364.odin %COMMON%  || exit /b
 ..\..\..\odin test ..\test_issue_4584.odin %COMMON%  || exit /b
 ..\..\..\odin build ..\test_issue_5043.odin %COMMON% || exit /b
 ..\..\..\odin build ..\test_issue_5097.odin %COMMON% || exit /b
diff --git a/tests/issues/run.sh b/tests/issues/run.sh
index 228efce7f..fc8ab513f 100755
--- a/tests/issues/run.sh
+++ b/tests/issues/run.sh
@@ -18,6 +18,7 @@ $ODIN test ../test_issue_2615.odin $COMMON
 $ODIN test ../test_issue_2637.odin $COMMON
 $ODIN test ../test_issue_2666.odin $COMMON
 $ODIN test ../test_issue_4210.odin $COMMON
+$ODIN test ../test_issue_4364.odin $COMMON
 $ODIN test ../test_issue_4584.odin $COMMON
 if [[ $($ODIN build ../test_issue_2395.odin $COMMON 2>&1 >/dev/null | grep -c "Error:") -eq 2 ]] ; then
 	echo "SUCCESSFUL 1/1"
diff --git a/tests/issues/test_issue_4364.odin b/tests/issues/test_issue_4364.odin
new file mode 100644
index 000000000..817a1a26b
--- /dev/null
+++ b/tests/issues/test_issue_4364.odin
@@ -0,0 +1,18 @@
+// Tests issue #4364 https://github.com/odin-lang/Odin/issues/4364
+package test_issues
+
+import "core:testing"
+
+@test
+test_const_array_fill_assignment :: proc(t: ^testing.T) {
+	MAGIC :: 12345
+	Struct :: struct {x: int}
+	CONST_ARR : [4]Struct : Struct{MAGIC}
+	arr := CONST_ARR
+
+	testing.expect_value(t, len(arr), 4)
+	testing.expect_value(t, arr[0], Struct{MAGIC})
+	testing.expect_value(t, arr[1], Struct{MAGIC})
+	testing.expect_value(t, arr[2], Struct{MAGIC})
+	testing.expect_value(t, arr[3], Struct{MAGIC})
+}