Fix wrong diagnostic when checking identical casting expr. (#8727)

`SemanticsVisitor::CheckInvokeExprWithCheckedOperands` made several
references to `expr` parameter in its `inout` parameter l-value-ness
validation logic to access arguments, which is wrong because `expr` is
not necessarily the same as `result`/`invoke` (the result of calling
`ResolveInvoke()` in the first line of the function. Changing it to
`invoke` for consistency.

Also add a special case logic to return early in case the resolved
invoke expr is `argument[0]` when the original invoke expr is
`T(funcThatReturnsT())`.

Closes #8659.

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/bugs/gh-8659.slang b/tests/bugs/gh-8659.slang
new file mode 100644
index 000000000..599c09b3b
--- /dev/null
+++ b/tests/bugs/gh-8659.slang
@@ -0,0 +1,16 @@
+//TEST:COMPARE_COMPUTE(filecheck-buffer=CHECK):-vk -output-using-type -emit-spirv-directly
+
+//TEST_INPUT: set ptr = ubuffer(data=[0 0 0 0], stride=4)
+uniform uint* ptr;
+
+//TEST_INPUT: set outputBuffer = out ubuffer(data=[0 0 0 0], stride=4)
+RWStructuredBuffer<uint> outputBuffer;
+
+[numthreads(1,1,1)]
+void computeMain()
+{
+    let indices = (uint*)&ptr[0];
+    *indices = 100;
+    // CHECK: 100
+    outputBuffer[0] = ptr[0];
+}
\ No newline at end of file