Support `expand` on concrete tuple values. (#8106)

Closes #8061.

Along with the fix, also enhanced coercion/overload resolution to filter
candidates based on the target type, allowing
`tests\language-feature\higher-order-functions\overloaded.slang` to
pass.

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/language-feature/tuple/tuple-expand-call.slang b/tests/language-feature/tuple/tuple-expand-call.slang
new file mode 100644
index 000000000..f2293f03f
--- /dev/null
+++ b/tests/language-feature/tuple/tuple-expand-call.slang
@@ -0,0 +1,26 @@
+//TEST:COMPARE_COMPUTE(filecheck-buffer=CHECK): -output-using-type
+
+//TEST_INPUT: set outputBuffer = out ubuffer(data=[0 0], stride=4)
+
+#lang 2026
+
+RWStructuredBuffer<int> outputBuffer;
+
+int f(int x, float y) { return x + int(y); }
+
+int g<each T>(expand each Tuple<expand each T> t)
+{
+    return countof(t);
+}
+
+[numthreads(1,1,1)]
+void computeMain()
+{
+    Tuple<expand each Tuple<int, float>> x = (2, 3.0f);
+    
+    // CHECK: 2
+    outputBuffer[0] = g<int, float>(expand each x);
+
+    // CHECK: 5
+    outputBuffer[1] = f(expand each x);
+}