Allow serenum members initializers refer to other serenum members (#3617

)

Signed-off-by: Mihai Budiu <[email protected]>

frontends/p4/typeChecking/typeChecker.cpp

@@ -1386,11 +1386,7 @@ const IR::Node* TypeInference::postorder(IR::Type_Enum* type) {
     return type;
 }
 
-const IR::Node* TypeInference::postorder(IR::Type_SerEnum* type) {
-    if (::errorCount())
-        // If we failed to typecheck a SerEnumMember we do not
-        // want to set the type for the SerEnum either.
-        return type;
+const IR::Node* TypeInference::preorder(IR::Type_SerEnum* type) {
     auto canon = setTypeType(type);
     for (auto e : *type->getDeclarations())
         setType(e->getNode(), canon);
@@ -1432,8 +1428,11 @@ const IR::Node* TypeInference::postorder(IR::Type_Set* type) {
 }
 
 const IR::Node* TypeInference::postorder(IR::SerEnumMember* member) {
-    if (done())
-        return member;
+    /*
+      The type of the member is initially set in the Type_SerEnum preorder visitor.
+      Here we check additional constraints and we may correct the member.
+      if (done()) return member;
+    */
     auto serEnum = findContext<IR::Type_SerEnum>();
     CHECK_NULL(serEnum);
     auto type = getTypeType(serEnum->type);
@@ -1442,9 +1441,9 @@ const IR::Node* TypeInference::postorder(IR::SerEnumMember* member) {
         return member;
     }
     auto exprType = getType(member->value);
-    auto tvs = unify(member, type, exprType,
-                     "Enum member '%1%' has type '%2%' and not the expected type '%2%'",
-                     { member, exprType, type });
+    auto tvs = unifyCast(member, type, exprType,
+                         "Enum member '%1%' has type '%2%' and not the expected type '%3%'",
+                         { member, exprType, type });
     if (tvs == nullptr)
         // error already signalled
         return member;
@@ -1453,6 +1452,8 @@ const IR::Node* TypeInference::postorder(IR::SerEnumMember* member) {
 
     ConstantTypeSubstitution cts(tvs, refMap, typeMap, this);
     member->value = cts.convert(member->value);  // sets type
+    if (!typeMap->getType(member))
+        setType(member, getTypeType(serEnum));
     return member;
 }
 

frontends/p4/typeChecking/typeChecker.h

@@ -222,6 +222,7 @@ class TypeInference : public Transform {
     const IR::Node* preorder(IR::Declaration_Instance* decl) override;
     // check invariants for entire list before checking the entries
     const IR::Node* preorder(IR::EntriesList* el) override;
+    const IR::Node* preorder(IR::Type_SerEnum* type) override;
 
     const IR::Node* postorder(IR::Declaration_MatchKind* decl) override;
     const IR::Node* postorder(IR::Declaration_Variable* decl) override;
@@ -239,7 +240,6 @@ class TypeInference : public Transform {
     const IR::Node* postorder(IR::Type_Base* type) override;
     const IR::Node* postorder(IR::Type_Var* type) override;
     const IR::Node* postorder(IR::Type_Enum* type) override;
-    const IR::Node* postorder(IR::Type_SerEnum* type) override;
     const IR::Node* postorder(IR::Type_Extern* type) override;
     const IR::Node* postorder(IR::StructField* field) override;
     const IR::Node* postorder(IR::Type_Header* type) override;

testdata/p4_16_errors_outputs/serenum-type.p4-stderr

@@ -1,6 +1,14 @@
 serenum-type.p4(8): [--Werror=type-error] error: EthT: Illegal type for enum; only bit<> and int<> are allowed
 enum EthT EthTypes {
      ^^^^
-serenum-type.p4(57): [--Werror=type-error] error: prs: cannot evaluate to a compile-time constant
-top(prs(), c()) main;
-    ^^^^^
+serenum-type.p4(49): [--Werror=type-error] error: cast
+            h.eth.type = (EthTypes)(bit<16>)0;
+                         ^^^^^^^^^^^^^^^^^^^^
+  ---- Actual error:
+serenum-type.p4(8): Cannot unify type 'bit<16>' with type 'EthTypes'
+  enum EthT EthTypes {
+            ^^^^^^^^
+  ---- Originating from:
+serenum-type.p4(8): Cannot cast from 'bit<16>' to 'EthTypes'
+  enum EthT EthTypes {
+            ^^^^^^^^

testdata/p4_16_errors_outputs/serenum-typedef.p4-stderr

@@ -1,6 +1,14 @@
 serenum-typedef.p4(8): [--Werror=type-error] error: EthT: Illegal type for enum; only bit<> and int<> are allowed
 enum EthT EthTypes {
      ^^^^
-serenum-typedef.p4(57): [--Werror=type-error] error: prs: cannot evaluate to a compile-time constant
-top(prs(), c()) main;
-    ^^^^^
+serenum-typedef.p4(49): [--Werror=type-error] error: cast
+            h.eth.type = (EthTypes)(bit<16>)0;
+                         ^^^^^^^^^^^^^^^^^^^^
+  ---- Actual error:
+serenum-typedef.p4(8): Cannot unify type 'bit<16>' with type 'EthTypes'
+  enum EthT EthTypes {
+            ^^^^^^^^
+  ---- Originating from:
+serenum-typedef.p4(8): Cannot cast from 'bit<16>' to 'EthTypes'
+  enum EthT EthTypes {
+            ^^^^^^^^

testdata/p4_16_samples/issue3616.p4

@@ -0,0 +1,6 @@
+enum bit<4> e {
+    a = 0,
+    b = 0,
+    c = (bit<4>)a,
+    d = a
+}

testdata/p4_16_samples_outputs/issue3616-first.p4

@@ -0,0 +1,7 @@
+enum bit<4> e {
+    a = 4w0,
+    b = 4w0,
+    c = (bit<4>)a,
+    d = a
+}
+

testdata/p4_16_samples_outputs/issue3616.p4

@@ -0,0 +1,7 @@
+enum bit<4> e {
+    a = 0,
+    b = 0,
+    c = (bit<4>)a,
+    d = a
+}
+

testdata/p4_16_samples_outputs/issue3616.p4-stderr

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