10 files changed, 68 insertions, 14 deletions
diff --git a/tests/autodiff/reverse-inout-param-custom-derivative.slang b/tests/autodiff/reverse-inout-param-custom-derivative.slang
index 8769a33c7..c4549e37b 100644
--- a/tests/autodiff/reverse-inout-param-custom-derivative.slang
+++ b/tests/autodiff/reverse-inout-param-custom-derivative.slang
@@ -5,7 +5,7 @@
 //TEST_INPUT:ubuffer(data=[0], stride=4):out,name=outputBuffer
 RWStructuredBuffer<float> outputBuffer;
 
-float rng(inout int state, float x)
+float rng(int state, float x)
 {
     return state + x;
 }
diff --git a/tests/bugs/gl-33-ext.slang b/tests/bugs/gl-33-ext.slang
index fccde99a3..6df9f286a 100644
--- a/tests/bugs/gl-33-ext.slang
+++ b/tests/bugs/gl-33-ext.slang
@@ -4,5 +4,5 @@
 public struct A
 {
     public int state;
-    [mutating] public int next() { return state; }
+    public int next() { return state; }
 };
diff --git a/tests/bugs/optional.slang b/tests/bugs/optional.slang
index 3512ba29f..7a220b23d 100644
--- a/tests/bugs/optional.slang
+++ b/tests/bugs/optional.slang
@@ -14,7 +14,7 @@ struct P
 }
 struct Tr
 {
-    int test<T:IArithmetic>(T t, inout P p)
+    int test<T:IArithmetic>(T t, P p)
     {
         const IFoo hit = p.f;
         let castResult = hit as S;
diff --git a/tests/diagnostics/inout-never-written.slang b/tests/diagnostics/inout-never-written.slang
new file mode 100644
index 000000000..0bc59ecf3
--- /dev/null
+++ b/tests/diagnostics/inout-never-written.slang
@@ -0,0 +1,48 @@
+//TEST:SIMPLE(filecheck=CHK): -target spirv
+
+struct State
+{
+    float3 v;
+    float3 n;
+    int rnd;
+};
+
+//CHK-DAG: ([[# @LINE + 1]]): warning 41022: inout parameter 'x' is never written to
+void int_never_assigned(inout int x) {}
+
+//CHK-DAG: ([[# @LINE + 1]]): warning 41022: inout parameter 'state' is never written to
+void state_never_assigned(inout State state, inout float v)
+{
+    v = state.v.x;
+}
+
+void state_assigned(inout State state)
+{
+    state.rnd = (int) dot(state.v, state.n);
+}
+
+struct A
+{
+    int state;
+
+    //CHK-DAG: ([[# @LINE + 1]]): warning 41023: method marked `[mutable]` but never modifies `this`
+    [mutating] int next() { return state; }
+    
+    [mutating] int progress()
+    {
+        unmodified(state);
+        return state;
+    }
+};
+
+__generic <T>
+struct B
+{
+    int state;
+
+    //CHK-DAG: ([[# @LINE + 1]]): warning 41023: method marked `[mutable]` but never modifies `this`
+    [mutating] int next() { return state; }
+};
+
+//CHK-NOT: warning 41022
+//CHK-NOT: warning 41023
+\ No newline at end of file
diff --git a/tests/hlsl-intrinsic/matrix-double.slang b/tests/hlsl-intrinsic/matrix-double.slang
index 31ec54f8e..6ed1b42bf 100644
--- a/tests/hlsl-intrinsic/matrix-double.slang
+++ b/tests/hlsl-intrinsic/matrix-double.slang
@@ -46,6 +46,8 @@ IntMatrix makeIntMatrix(int v)
 
 void test1(inout FloatMatrix ft, inout FloatMatrix f, int idx)
 {
+    unmodified(f);
+
     // fmod
     ft += FloatMatrix(IntMatrix(((f % makeFloatMatrix(0.11f)) * makeFloatMatrix(100)) + makeFloatMatrix(0.5)));
 
@@ -112,6 +114,8 @@ void test1(inout FloatMatrix ft, inout FloatMatrix f, int idx)
 
 void test2(inout FloatMatrix ft, inout FloatMatrix f)
 {
+    unmodified(f);
+
     ft += pow(makeFloatMatrix(0.5), f);
 
     ft += smoothstep(makeFloatMatrix(0.2), makeFloatMatrix(0.7), f);
diff --git a/tests/hlsl-intrinsic/size-of/align-of-3.slang b/tests/hlsl-intrinsic/size-of/align-of-3.slang
index 28665b5ab..079de9241 100644
--- a/tests/hlsl-intrinsic/size-of/align-of-3.slang
+++ b/tests/hlsl-intrinsic/size-of/align-of-3.slang
@@ -10,7 +10,7 @@
 RWStructuredBuffer<int> outputBuffer;
 
 
-int getParamSize(inout uint3 v)
+int getParamSize(uint3 v)
 {
     return alignof(v);
 }
@@ -19,7 +19,7 @@ int getParamSize(inout uint3 v)
 // With "natural" layout size must be the same across all targets.
 // The parameter passing semantic is "value in/value out", so the size 
 // will always be the size of the *value* regardless. So uint3 in this case.
-int getParamSizeWithDirection(inout uint3 v)
+int getParamSizeWithDirection(uint3 v)
 {
     return alignof(v);
 }
diff --git a/tests/hlsl-intrinsic/size-of/size-of-3.slang b/tests/hlsl-intrinsic/size-of/size-of-3.slang
index 8a211867f..7e55bd320 100644
--- a/tests/hlsl-intrinsic/size-of/size-of-3.slang
+++ b/tests/hlsl-intrinsic/size-of/size-of-3.slang
@@ -10,7 +10,7 @@
 RWStructuredBuffer<int> outputBuffer;
 
 
-int getParamSize(inout uint3 v)
+int getParamSize(uint3 v)
 {
     return sizeof(v);
 }
@@ -19,7 +19,7 @@ int getParamSize(inout uint3 v)
 // With "natural" layout size must be the same across all targets.
 // The parameter passing semantic is "value in/value out", so the size 
 // will always be the size of the *value* regardless. So uint3 in this case.
-int getParamSizeWithDirection(inout uint3 v)
+int getParamSizeWithDirection(uint3 v)
 {
     return sizeof(v);
 }
diff --git a/tests/language-feature/struct-field-initializers/struct-field-no-initializer-complex-types.slang b/tests/language-feature/struct-field-initializers/struct-field-no-initializer-complex-types.slang
index a55c4725d..66a3a2c64 100644
--- a/tests/language-feature/struct-field-initializers/struct-field-no-initializer-complex-types.slang
+++ b/tests/language-feature/struct-field-initializers/struct-field-no-initializer-complex-types.slang
@@ -6,7 +6,7 @@
 //TEST_INPUT:ubuffer(data=[0 0], stride=4):out,name=outputBuffer
 RWStructuredBuffer<int> outputBuffer;
 
-struct DefaultData
+struct DefaultData : IDefaultInitializable
 {
     static const int2 val = int2(0, 1);
     float2 size;
@@ -16,13 +16,10 @@ struct DefaultData
 
 extension DefaultData
 {
-    int someGet()
-    {
-        return val.x;
-    }
+    int someGet() { return val.x; }
 }
 
-int loadDefaultData(inout DefaultData noInit)
+int loadDefaultData(DefaultData noInit)
 {
     outputBuffer[1] = 1;
     return noInit.someGet();
diff --git a/tests/language-feature/unsized-array.slang b/tests/language-feature/unsized-array.slang
index c4479867e..19ab0bd63 100644
--- a/tests/language-feature/unsized-array.slang
+++ b/tests/language-feature/unsized-array.slang
@@ -17,6 +17,7 @@ int test(int arr[])
 
 int test2<T>(inout T arr[])
 {
+    unmodified(arr);
     return arr.getCount();
 }
 
diff --git a/tests/pipeline/ray-tracing/trace-ray-inline.slang b/tests/pipeline/ray-tracing/trace-ray-inline.slang
index 009dffbc7..b8688c2f5 100644
--- a/tests/pipeline/ray-tracing/trace-ray-inline.slang
+++ b/tests/pipeline/ray-tracing/trace-ray-inline.slang
@@ -57,6 +57,7 @@ void myTriangleClosestHit(inout MyRayPayload payload)
 //
 bool myTriangleAnyHit(inout MyRayPayload payload)
 {
+    unmodified(payload);
 	return true;
 }
 
@@ -75,6 +76,7 @@ void myProceduralClosestHit(inout MyRayPayload payload, MyProceduralHitAttrs att
 }
 bool myProceduralAnyHit(inout MyRayPayload payload)
 {
+    unmodified(payload);
 	return true;
 }
 
@@ -87,6 +89,8 @@ bool myProceduralAnyHit(inout MyRayPayload payload)
 //
 bool myProceduralIntersection(inout float tHit, inout MyProceduralHitAttrs hitAttrs)
 {
+    unmodified(tHit);
+    unmodified(hitAttrs);
 	return true;
 }
 
@@ -180,4 +184,4 @@ void main(uint3 tid : SV_DispatchThreadID)
 	}
 
     resultBuffer[index] = payload.value;
-}
-\ No newline at end of file
+}