Report error on nested functions. (#5792)

* Report error on nested functions.

* Fix.

---------

Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>

Author: csyonghe

source/slang/slang-parser.cpp

@@ -5783,6 +5783,27 @@ DeclStmt* Parser::parseVarDeclrStatement(Modifiers modifiers)
     FillPosition(varDeclrStatement);
     auto decl = ParseDeclWithModifiers(this, currentScope->containerDecl, modifiers);
     varDeclrStatement->decl = decl;
+
+    if (as<VarDeclBase>(decl))
+    {
+    }
+    else if (as<DeclGroup>(decl))
+    {
+    }
+    else if (as<AggTypeDecl>(decl))
+    {
+    }
+    else if (as<TypeDefDecl>(decl))
+    {
+    }
+    else if (as<UsingDecl>(decl))
+    {
+    }
+    else
+    {
+        sink->diagnose(decl->loc, Diagnostics::declNotAllowed, decl->astNodeType);
+    }
+
     return varDeclrStatement;
 }
 

tests/diagnostics/nested-func.slang

@@ -0,0 +1,12 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
+
+
+struct VertexOutput{float Input;}
+float4 fragmentMain(VertexOutput vertex) : SV_Target
+{
+   // CHECK: ([[# @LINE+1]]): error 30102
+  static float GetValue(int val) { return vertex.Input; } // Simplified example
+  float a = GetValue(vertex.Input);
+
+  // etc
+}

tests/diagnostics/uninitialized-local-variables.slang

@@ -1,10 +1,10 @@
 //TEST:SIMPLE(filecheck=CHK): -target spirv
 
+float f(float) { return 1; }
+
 // Should not warn here (unconditionalBranch)
 float3 unconditional(int mode)
 {
-    float f(float) { return 1; }
-
     float k0;
     float k1;