From f374988f770c3423b10b03afeff6cb7c924c4a12 Mon Sep 17 00:00:00 2001
From: Chris Dodd <cdodd@nvidia.com>
Date: Thu, 4 Apr 2024 23:31:17 +0000
Subject: [PATCH] Allow implicit conversion of brace-lists to type list

---
 frontends/p4/typeChecking/typeUnification.cpp  | 18 +++++++++++++-----
 testdata/p4_16_samples/listinit.p4             | 14 ++++++++++++++
 .../p4_16_samples_outputs/listinit-first.p4    |  7 +++++++
 .../p4_16_samples_outputs/listinit-frontend.p4 |  7 +++++++
 testdata/p4_16_samples_outputs/listinit.p4     |  7 +++++++
 .../p4_16_samples_outputs/listinit.p4-stderr   | 10 ++++++++++
 6 files changed, 58 insertions(+), 5 deletions(-)
 create mode 100644 testdata/p4_16_samples/listinit.p4
 create mode 100644 testdata/p4_16_samples_outputs/listinit-first.p4
 create mode 100644 testdata/p4_16_samples_outputs/listinit-frontend.p4
 create mode 100644 testdata/p4_16_samples_outputs/listinit.p4
 create mode 100644 testdata/p4_16_samples_outputs/listinit.p4-stderr

diff --git a/frontends/p4/typeChecking/typeUnification.cpp b/frontends/p4/typeChecking/typeUnification.cpp
index 98bce43871c..aae3d5102f0 100644
--- a/frontends/p4/typeChecking/typeUnification.cpp
+++ b/frontends/p4/typeChecking/typeUnification.cpp
@@ -487,11 +487,19 @@ bool TypeUnification::unify(const BinaryConstraint *constraint) {
             }
             return true;
         }
-    } else if (dest->is<IR::Type_P4List>() && src->is<IR::Type_P4List>()) {
-        auto dvec = dest->to<IR::Type_P4List>();
-        auto svec = src->to<IR::Type_P4List>();
-        constraints->add(constraint->create(dvec->elementType, svec->elementType));
-        return true;
+    } else if (auto dvec = dest->to<IR::Type_P4List>()) {
+        if (auto svec = src->to<IR::Type_P4List>()) {
+            constraints->add(constraint->create(dvec->elementType, svec->elementType));
+            return true;
+        } else if (auto svec = src->to<IR::Type_List>()) {
+            std::set<const IR::Type *> elTypes;
+            for (auto *t : svec->components) {
+                if (elTypes.count(t)) continue;
+                elTypes.insert(t);
+                constraints->add(constraint->create(dvec->elementType, t));
+            }
+            return true;
+        }
     }
 
     return constraint->reportError(constraints->getCurrentSubstitution());
diff --git a/testdata/p4_16_samples/listinit.p4 b/testdata/p4_16_samples/listinit.p4
new file mode 100644
index 00000000000..152ee3f5a54
--- /dev/null
+++ b/testdata/p4_16_samples/listinit.p4
@@ -0,0 +1,14 @@
+
+extern test<T1, T2> {
+  test(list<tuple<T1, T2>> pairs);
+}
+
+test<bit<16>, _>({
+    { 16w0, "foo" },
+    { 16w1, "bar" },
+    { 16w2, "baz" }
+}) obj;
+
+test<bit<16>, _>({}) o2;
+
+test<bit<16>, bit<8>>({ { 0, 10}, { 1, 12 }, { 2, 15 } }) o3;
diff --git a/testdata/p4_16_samples_outputs/listinit-first.p4 b/testdata/p4_16_samples_outputs/listinit-first.p4
new file mode 100644
index 00000000000..5915d633a9e
--- /dev/null
+++ b/testdata/p4_16_samples_outputs/listinit-first.p4
@@ -0,0 +1,7 @@
+extern test<T1, T2> {
+    test(list<tuple<T1, T2>> pairs);
+}
+
+test<bit<16>, _>({ { 16w0, "foo" }, { 16w1, "bar" }, { 16w2, "baz" } }) obj;
+test<bit<16>, _>({  }) o2;
+test<bit<16>, bit<8>>({ { 0, 10 }, { 1, 12 }, { 2, 15 } }) o3;
diff --git a/testdata/p4_16_samples_outputs/listinit-frontend.p4 b/testdata/p4_16_samples_outputs/listinit-frontend.p4
new file mode 100644
index 00000000000..5915d633a9e
--- /dev/null
+++ b/testdata/p4_16_samples_outputs/listinit-frontend.p4
@@ -0,0 +1,7 @@
+extern test<T1, T2> {
+    test(list<tuple<T1, T2>> pairs);
+}
+
+test<bit<16>, _>({ { 16w0, "foo" }, { 16w1, "bar" }, { 16w2, "baz" } }) obj;
+test<bit<16>, _>({  }) o2;
+test<bit<16>, bit<8>>({ { 0, 10 }, { 1, 12 }, { 2, 15 } }) o3;
diff --git a/testdata/p4_16_samples_outputs/listinit.p4 b/testdata/p4_16_samples_outputs/listinit.p4
new file mode 100644
index 00000000000..5915d633a9e
--- /dev/null
+++ b/testdata/p4_16_samples_outputs/listinit.p4
@@ -0,0 +1,7 @@
+extern test<T1, T2> {
+    test(list<tuple<T1, T2>> pairs);
+}
+
+test<bit<16>, _>({ { 16w0, "foo" }, { 16w1, "bar" }, { 16w2, "baz" } }) obj;
+test<bit<16>, _>({  }) o2;
+test<bit<16>, bit<8>>({ { 0, 10 }, { 1, 12 }, { 2, 15 } }) o3;
diff --git a/testdata/p4_16_samples_outputs/listinit.p4-stderr b/testdata/p4_16_samples_outputs/listinit.p4-stderr
new file mode 100644
index 00000000000..180e9bda066
--- /dev/null
+++ b/testdata/p4_16_samples_outputs/listinit.p4-stderr
@@ -0,0 +1,10 @@
+listinit.p4(10): [--Wwarn=unused] warning: obj: unused instance
+}) obj;
+   ^^^
+listinit.p4(12): [--Wwarn=unused] warning: o2: unused instance
+test<bit<16>, _>({}) o2;
+                     ^^
+listinit.p4(14): [--Wwarn=unused] warning: o3: unused instance
+test<bit<16>, bit<8>>({ { 0, 10}, { 1, 12 }, { 2, 15 } }) o3;
+                                                          ^^
+[--Wwarn=missing] warning: Program does not contain a `main' module