Add diagnostic to prevent defining unsized variables. (#4168)

* Add diagnostic to prevent defining unsized static variables.

* Fix tests.

* Add more tests.

* Fix to allow defining variables of link-time size.

* update diagnostic message.

* Fix tests.

* Simplify code.

1 files changed, 17 insertions, 2 deletions

diff --git a/source/slang/slang-check-overload.cpp b/source/slang/slang-check-overload.cpp
index 6b51493e1..367c200cc 100644
--- a/source/slang/slang-check-overload.cpp
+++ b/source/slang/slang-check-overload.cpp
@@ -263,6 +263,14 @@ namespace Slang
         //
         bool success = true;
 
+        auto maybeReportGeneralError = [&]()
+        {
+            if (context.mode != OverloadResolveContext::Mode::JustTrying)
+            {
+                getSink()->diagnose(context.loc, Diagnostics::cannotSpecializeGeneric, candidate.item.declRef);
+            }
+        };
+
         Index aa = 0;
         for (auto memberRef : getMembers(m_astBuilder, genericDeclRef))
         {
@@ -287,7 +295,10 @@ namespace Slang
                         // or this reference is ill-formed.
                         auto substType = typeParamRef.substitute(m_astBuilder, typeParamRef.getDecl()->initType.type);
                         if (!substType)
+                        {
+                            maybeReportGeneralError();
                             return false;
+                        }
                         checkedArgs.add(substType);
                         continue;
                     }
@@ -355,7 +366,10 @@ namespace Slang
                         ConstantFoldingCircularityInfo newCircularityInfo(valParamRef.getDecl(), nullptr);
                         auto defaultVal = tryConstantFoldExpr(valParamRef.substitute(m_astBuilder, valParamRef.getDecl()->initExpr), ConstantFoldingKind::CompileTime, &newCircularityInfo);
                         if (!defaultVal)
+                        {
+                            maybeReportGeneralError();
                             return false;
+                        }
                         checkedArgs.add(defaultVal);
                         continue;
                     }
@@ -475,8 +489,9 @@ namespace Slang
             break;
 
         case OverloadCandidate::Flavor::Generic:
-            return TryCheckGenericOverloadCandidateTypes(context, candidate);
-
+            {
+                return TryCheckGenericOverloadCandidateTypes(context, candidate);
+            }
         default:
             SLANG_UNEXPECTED("unknown flavor of overload candidate");
             break;