From 640a0f2ef49b347f0a10dd6b1c2034306352a9df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A4rtschi=20Robin?= <Robin.Baertschi@swisscom.com>
Date: Wed, 24 Jun 2026 08:31:46 +0200
Subject: [PATCH] add test for #6874

---
 tests/issues/run.bat              |  1 +
 tests/issues/run.sh               |  6 ++++++
 tests/issues/test_issue_6874.odin | 35 +++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)
 create mode 100644 tests/issues/test_issue_6874.odin

diff --git a/tests/issues/run.bat b/tests/issues/run.bat
index 0b92f07ff..43a7136b7 100644
--- a/tests/issues/run.bat
+++ b/tests/issues/run.bat
@@ -36,6 +36,7 @@ set COMMON=-define:ODIN_TEST_FANCY=false -file -vet -strict-style -ignore-unused
 ..\..\..\odin test ..\test_pr_6470.odin -define:TEST_EXPECT_FAILURE=true %COMMON% 2>&1 | find /c "Error:" | findstr /x "1" || exit /b
 ..\..\..\odin test ..\test_pr_6476.odin %COMMON%  || exit /b
 ..\..\..\odin check ..\test_issue_6484.odin -no-entry-point %COMMON%  || exit /b
+..\..\..\odin check ..\test_issue_6874.odin %COMMON% 2>&1 | find /c "Error:" | findstr /x "1" || exit /b
 
 @echo off
 
diff --git a/tests/issues/run.sh b/tests/issues/run.sh
index f630738f9..3633a7606 100755
--- a/tests/issues/run.sh
+++ b/tests/issues/run.sh
@@ -73,6 +73,12 @@ else
 	exit 1
 fi
 $ODIN check ../test_issue_6484.odin -no-entry-point $COMMON
+if [[ $($ODIN check ../test_issue_6874.odin $COMMON 2>&1 >/dev/null | grep -c "Error:") -eq 1 ]] ; then
+	echo "SUCCESSFUL 1/1"
+else
+	echo "SUCCESSFUL 0/1"
+	exit 1
+fi
 
 set +x
 
diff --git a/tests/issues/test_issue_6874.odin b/tests/issues/test_issue_6874.odin
new file mode 100644
index 000000000..751e12ebe
--- /dev/null
+++ b/tests/issues/test_issue_6874.odin
@@ -0,0 +1,35 @@
+// Test for issue #6874 https://github.com/odin-lang/Odin/issues/6874
+
+package test_issues
+
+import "core:fmt"
+
+PersonData :: struct {
+    health: int,
+    age: int,
+}
+
+MyUnion :: union {
+    f32,
+    int,
+    PersonData,
+}
+
+change_union_data :: proc(data: MyUnion) {
+    switch &v in data {
+    case int:
+        v = 10
+    case f32:
+        fmt.println("f32")
+    case PersonData:
+        fmt.println("PersonData")
+        fmt.println(v)
+    }
+}
+
+main :: proc() {
+    val: MyUnion = int(12)
+    fmt.printfln("Before the call: %v", val)
+    change_union_data(val)
+    fmt.printfln("After the call: %v", val)
+}
\ No newline at end of file