Do not specialize functions when arguments are type variables (#3328)

Signed-off-by: Mihai Budiu <mbudiu@vmware.com>

frontends/p4/specializeGenericFunctions.cpp

@@ -21,6 +21,12 @@ namespace P4 {
 bool FindFunctionSpecializations::preorder(const IR::MethodCallExpression* mce) {
     if (!mce->typeArguments->size())
         return false;
+    // We only specialize if the type arguments are not type variables
+    for (auto arg : *mce->typeArguments) {
+        auto type = specMap->typeMap->getTypeType(arg, true);
+        if (type->is<IR::ITypeVar>())
+            return false;
+    }
     MethodInstance *mi = MethodInstance::resolve(mce, specMap->refMap, specMap->typeMap);
     if (auto func = mi->to<FunctionCall>()) {
         LOG3("Will specialize " << mce);

testdata/p4_16_samples/issue3324.p4

@@ -0,0 +1,5 @@
+void f<t>(in t a){ }
+void g<t>(in t b)
+{
+  f(b);
+}

testdata/p4_16_samples_outputs/issue3324-first.p4

@@ -0,0 +1,5 @@
+void f<t>(in t a) {
+}
+void g<t>(in t b) {
+    f<t>(b);
+}

testdata/p4_16_samples_outputs/issue3324.p4

@@ -0,0 +1,5 @@
+void f<t>(in t a) {
+}
+void g<t>(in t b) {
+    f(b);
+}

testdata/p4_16_samples_outputs/issue3324.p4-stderr

@@ -0,0 +1 @@
+[--Wwarn=missing] warning: Program does not contain a `main' module