Support link-time constants. (#3564)

* Support link-time constants.

* Fix.

* Fix.

4 files changed, 44 insertions, 16 deletions

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index 3882994da..2a6ee8abc 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -1471,6 +1471,11 @@ namespace Slang
             }
             else
             {
+                if (varDecl->hasModifier<ExternModifier>())
+                {
+                    getSink()->diagnose(initExpr, Diagnostics::externValueCannotHaveInitializer);
+                }
+
                 initExpr = CheckExpr(initExpr);
 
                 // TODO: We might need some additional steps here to ensure
@@ -1484,7 +1489,7 @@ namespace Slang
 
                 _validateCircularVarDefinition(varDecl);
             }
-
+            
             // If we've gone down this path, then the variable
             // declaration is actually pretty far along in checking
             varDecl->setCheckState(DeclCheckState::DefinitionChecked);
diff --git a/source/slang/slang-check-expr.cpp b/source/slang/slang-check-expr.cpp
index 2f4906826..c04cb73e4 100644
--- a/source/slang/slang-check-expr.cpp
+++ b/source/slang/slang-check-expr.cpp
@@ -1659,6 +1659,9 @@ namespace Slang
             return nullptr;
         if(!decl->hasModifier<ConstModifier>())
             return nullptr;
+        // Extern static const is not considered compile-time constant by the front-end.
+        if (decl->hasModifier<ExternModifier>())
+            return nullptr;
 
         if (isInterfaceRequirement(decl))
         {
diff --git a/source/slang/slang-diagnostic-defs.h b/source/slang/slang-diagnostic-defs.h
index 9b599ae2e..ac1f9aff9 100644
--- a/source/slang/slang-diagnostic-defs.h
+++ b/source/slang/slang-diagnostic-defs.h
@@ -478,10 +478,10 @@ DIAGNOSTIC(30502, Error, cannotUseInitializerListForVectorOfUnknownSize, "cannot
 DIAGNOSTIC(30503, Error, cannotUseInitializerListForMatrixOfUnknownSize, "cannot use initializer list for matrix of statically unknown size '$0' rows")
 DIAGNOSTIC(30504, Error, cannotUseInitializerListForType, "cannot use initializer list for type '$0'")
 
-// 306xx: variables
-DIAGNOSTIC(30600, Error, varWithoutTypeMustHaveInitializer, "a variable declaration without an initial-value expression must be given an explicit type")
-
-DIAGNOSTIC(30610, Error, ambiguousDefaultInitializerForType, "more than one default initializer was found for type '$0'")
+// 3062x: variables
+DIAGNOSTIC(30620, Error, varWithoutTypeMustHaveInitializer, "a variable declaration without an initial-value expression must be given an explicit type")
+DIAGNOSTIC(30621, Error, externValueCannotHaveInitializer, "an 'extern' variable declaration cannot have a value.")
+DIAGNOSTIC(30622, Error, ambiguousDefaultInitializerForType, "more than one default initializer was found for type '$0'")
 
 // 307xx: parameters
 DIAGNOSTIC(30700, Error, outputParameterCannotHaveDefaultValue, "an 'out' or 'inout' parameter cannot have a default-value expression")
diff --git a/source/slang/slang-mangle.cpp b/source/slang/slang-mangle.cpp
index 3f701f385..9431533ac 100644
--- a/source/slang/slang-mangle.cpp
+++ b/source/slang/slang-mangle.cpp
@@ -132,7 +132,8 @@ namespace Slang
 
     void emitQualifiedName(
         ManglingContext*    context,
-        DeclRef<Decl>       declRef);
+        DeclRef<Decl>       declRef,
+        bool includeModuleName);
 
     void emitSimpleIntVal(
         ManglingContext*    context,
@@ -211,7 +212,7 @@ namespace Slang
         }
         else if( auto declRefType = dynamicCast<DeclRefType>(type) )
         {
-            emitQualifiedName(context, declRefType->getDeclRef());
+            emitQualifiedName(context, declRefType->getDeclRef(), true);
         }
         else if (auto arrType = dynamicCast<ArrayExpressionType>(type))
         {
@@ -222,7 +223,7 @@ namespace Slang
         else if( auto thisType = dynamicCast<ThisType>(type) )
         {
             emitRaw(context, "t");
-            emitQualifiedName(context, thisType->getInterfaceDeclRef());
+            emitQualifiedName(context, thisType->getInterfaceDeclRef(), true);
         }
         else if (const auto errorType = dynamicCast<ErrorType>(type))
         {
@@ -356,8 +357,26 @@ namespace Slang
 
     void emitQualifiedName(
         ManglingContext*    context,
-        DeclRef<Decl>       declRef)
+        DeclRef<Decl>       declRef,
+        bool includeModuleName)
     {
+        if (!includeModuleName)
+        {
+            if (as<ModuleDecl>(declRef))
+                return;
+        }
+        else
+        {
+            for (auto modifier : declRef.getDecl()->modifiers)
+            {
+                if (as<ExternModifier>(modifier) || as<HLSLExportModifier>(modifier))
+                {
+                    includeModuleName = false;
+                    break;
+                }
+            }
+        }
+
         auto parentDeclRef = declRef.getParent();
         if (as<FileDecl>(parentDeclRef))
             parentDeclRef = parentDeclRef.getParent();
@@ -365,7 +384,7 @@ namespace Slang
         auto parentGenericDeclRef = parentDeclRef.as<GenericDecl>();
         if( parentDeclRef )
         {
-            emitQualifiedName(context, parentDeclRef);
+            emitQualifiedName(context, parentDeclRef, includeModuleName);
         }
 
         // A generic declaration is kind of a pseudo-declaration
@@ -490,7 +509,7 @@ namespace Slang
                     for (auto type : constraint.value)
                     {
                         emitRaw(context, "C");
-                        emitQualifiedName(context, makeDeclRef(constraint.key));
+                        emitQualifiedName(context, makeDeclRef(constraint.key), true);
                             emitType(context, type);
                     }
                 }
@@ -579,7 +598,7 @@ namespace Slang
 
             auto innerDecl = getInner(genericDecl);
 
-            emitQualifiedName(context, makeDeclRef(innerDecl));
+            emitQualifiedName(context, makeDeclRef(innerDecl), true);
             return;
         }
         else if (as<ForwardDerivativeRequirementDecl>(decl))
@@ -592,7 +611,8 @@ namespace Slang
         }
 
         // Now we encode the qualified name of the decl.
-        emitQualifiedName(context, declRef);
+        
+        emitQualifiedName(context, declRef, true);
     }
 
     static String getMangledName(ASTBuilder* astBuilder, DeclRef<Decl> const& declRef)
@@ -625,8 +645,8 @@ namespace Slang
         SLANG_AST_BUILDER_RAII(astBuilder);
         ManglingContext context(astBuilder);
         emitRaw(&context, "_SW");
-        emitQualifiedName(&context, sub);
-        emitQualifiedName(&context, sup);
+        emitQualifiedName(&context, sub, true);
+        emitQualifiedName(&context, sup, true);
         return context.sb.produceString();
     }
 
@@ -643,7 +663,7 @@ namespace Slang
         //
         ManglingContext context(astBuilder);
         emitRaw(&context, "_SW");
-        emitQualifiedName(&context, sub);
+        emitQualifiedName(&context, sub, true);
         emitType(&context, sup);
         return context.sb.produceString();
     }