Error if super-type capabilities are a super-set of sub-type (#7452)

Fixes: #7410

Changes:
1. super-type capabilities must be a super-set of sub-type capabilities
(and support the same shader stages/targets)
* InheritanceDecl visits super-type to inherit it's capabilities;
validate InheritanceDecl capabilities against sub-type
    * visit all container decl's with a default case 
    * clean up functionDeclBase visitor
* Simplify `diagnoseUndeclaredCapability` by moving logic into
capability checking (more correct*)
3. added changed behavior to documentation
4. fixed some incorrect capabilities
5. **we do not** diagnose capability errors on interface
requirement-to-implementation if both lack explicit capability
requirements. This change is to work around a slangpy regression (test
case for the failing situation is in
`tests\language-feature\capability\capability-interface-extension-1.slang`),
Note: maybe for slang-2026 we don't do this?
6. requirement & implementation must support the same shader
stage/target. This was changed because otherwise we can have cases where
`X` inherits from `Y`, but `Y` is only expected to be used in `glsl`
whilst `X` is expected to be used in `hlsl | glsl`
7. removed
`tests/language-feature/capability/capabilitySimplification3.slang`
because it tests nothing special (redundant)

Note: not using rebase due to separate branches depending on this PR

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>

1 files changed, 22 insertions, 5 deletions

diff --git a/tests/language-feature/capability/capability2.slang b/tests/language-feature/capability/capability2.slang
index 6125c21d3..354b87dd5 100644
--- a/tests/language-feature/capability/capability2.slang
+++ b/tests/language-feature/capability/capability2.slang
@@ -12,6 +12,11 @@ interface IFoo
     void method2();
 }
 
+interface IFoo2
+{
+    void method3();
+}
+
 [require(spvGroupNonUniformArithmetic)]
 void useNonUniformArithmetic()
 {}
@@ -39,20 +44,32 @@ struct Impl1 : IFoo
     }
 }
 
-struct Impl2 : IFoo
+struct Impl2 : IFoo, IFoo2
 {
-    // CHECK: error 36104: {{.*}}spvGroupNonUniformArithmetic
+    // error here because explicit requirement is on `method1`
+    // CHECK: error 36104:{{.*}}spvGroupNonUniformArithmetic
     void method1()
     {
-        useRayQueryKHR(); // OK.
-        useNonUniformArithmetic(); // error.
+        useRayQueryKHR();
+        useNonUniformArithmetic();
     }
 
+    // error here because capabilities are explicitly tagged on
+    // the requirement parent `IFoo`
     // CHECK: error 36104: {{.*}}spvGroupNonUniformArithmetic
     void method2()
     {
         useAtomicFloat16();
-        useNonUniformArithmetic(); // error.
+        useNonUniformArithmetic();
+    }
+
+    // do not error here because capabilities are not explicitly tagged 
+    // on the requirement parent `IFoo2` or requirment method
+    // CHECK-NOT: error
+    void method3()
+    {
+        useAtomicFloat16();
+        useNonUniformArithmetic();
     }
 }