Diagnose on initExpr of a global const decl

source/slang/slang-check-decl.cpp

@@ -212,22 +212,42 @@ struct SemanticsDeclModifiersVisitor : public SemanticsDeclVisitorBase,
         // Export'd/Extern'd variables must be `const`, otherwise we may have a mismatch
         // causing errors.
         bool hasConst = false;
+        bool hasUniform = false;
         bool hasExportOrExtern = false;
         bool hasStatic = false;
+        bool hasSpecializationConstant = false;
         for (auto m : decl->modifiers)
         {
             if (as<ExternModifier>(m) || as<HLSLExportModifier>(m))
                 hasExportOrExtern = true;
             else if (as<ConstModifier>(m))
                 hasConst = true;
+            else if (as<HLSLUniformModifier>(m))
+                hasUniform = true;
             else if (as<HLSLStaticModifier>(m))
                 hasStatic = true;
+            else if (as<SpecializationConstantAttribute>(m) || as<VkConstantIdAttribute>(m))
+                hasSpecializationConstant = true;
         }
         if (hasExportOrExtern && hasConst != hasStatic)
             getSink()->diagnose(
                 decl,
                 Diagnostics::ExternAndExportVarDeclMustBeConst,
                 decl->getName());
+
+
+        // Global const or uniform variables with initializers must be static
+        // In HLSL, const global variables without static are uniform parameters
+        // that cannot have default values
+        // Exception: specialization constants are allowed to have initializers
+        if (isGlobalDecl(decl) && (hasConst || hasUniform) && !hasStatic &&
+            !hasSpecializationConstant && decl->initExpr)
+        {
+            getSink()->diagnose(
+                decl,
+                Diagnostics::constGlobalVarWithInitRequiresStatic,
+                decl->getName());
+        }
     }
 
     void visitDecl(Decl* decl) { checkModifiers(decl); }

source/slang/slang-diagnostic-defs.h

@@ -1502,6 +1502,12 @@ DIAGNOSTIC(
     ExternAndExportVarDeclMustBeConst,
     "extern and export variables must be static const: '$0'")
 
+DIAGNOSTIC(
+    31224,
+    Error,
+    constGlobalVarWithInitRequiresStatic,
+    "global const variable with initializer must be declared static: '$0'")
+
 // Enums
 
 DIAGNOSTIC(32000, Error, invalidEnumTagType, "invalid tag type for 'enum': '$0'")

tests/diagnostics/global-const-uniform-with-init.slang

@@ -0,0 +1,49 @@
+//TEST:SIMPLE(filecheck=CHK): -target hlsl -entry main
+
+// Test for diagnostic 31224: global const/uniform variables with initializers must be static
+// Exception: specialization constants are allowed to have initializers without static
+// Test for diagnostic 31219: specialization constants cannot be declared static
+
+// These should trigger error 31224
+//CHK-DAG: ([[# @LINE + 1]]): error 31224: global const variable with initializer must be declared static: 'globalConstWithInit'
+const float globalConstWithInit = 1.0f;
+
+//CHK-DAG: ([[# @LINE + 1]]): error 31224: global const variable with initializer must be declared static: 'uniformWithInit'
+uniform float uniformWithInit = 2.0f;
+
+// These are valid and should not produce errors
+static const float staticConstWithInit = 3.0f;        // OK - static const with init
+const float globalConstNoInit;                        // OK - const without init
+uniform float uniformNoInit;                          // OK - uniform without init
+
+// Specialization constants with initializers are allowed without static
+[SpecializationConstant]
+const int specConstInt = 42;                          // OK - specialization constant with init
+
+[vk::constant_id(5)]
+const float specConstFloat = 3.14f;                   // OK - vk constant id with init
+
+// These should trigger error 31219: static specialization constants are not allowed
+//CHK-DAG: ([[# @LINE + 2]]): error 31219: push or specialization constants cannot be 'static'.
+[SpecializationConstant]
+static const int staticSpecConstInt = 100;
+
+//CHK-DAG: ([[# @LINE + 2]]): error 31219: push or specialization constants cannot be 'static'.
+[vk::constant_id(7)]
+static const float staticSpecConstFloat = 2.71f;
+
+void functionScope()
+{
+    const float localConstWithInit = 4.0f;           // OK - local const with init
+}
+
+struct MyStruct 
+{
+    static const float memberStaticConst = 5.0f;    // OK - member static const
+};
+
+[shader("vertex")]
+float4 main() : SV_Position
+{
+    return float4(staticConstWithInit, 0, 0, 1);
+}

tests/diagnostics/global-uniform.slang

@@ -7,7 +7,7 @@
 
 uniform float a;
 
-const uint4 b = uint4(0,1,2,3);
+static const uint4 b = uint4(0,1,2,3);
 
 struct C { float x; int y; };
 C c;

tests/diagnostics/global-uniform.slang.expected

@@ -1,8 +1,5 @@
 result code = 0
 standard error = {
-tests/diagnostics/global-uniform.slang(10): warning 39019: 'b' is implicitly a global shader parameter, not a global variable. If a global variable is intended, add the 'static' modifier. If a uniform shader parameter is intended, add the 'uniform' modifier to silence this warning.
-const uint4 b = uint4(0,1,2,3);
-            ^
 tests/diagnostics/global-uniform.slang(13): warning 39019: 'c' is implicitly a global shader parameter, not a global variable. If a global variable is intended, add the 'static' modifier. If a uniform shader parameter is intended, add the 'uniform' modifier to silence this warning.
 C c;
   ^