Make sure WithFields[AlwaysSet/Unset] overwrite a With[Min/Max]RepeatedFieldsSize.

Currently, `.WithFieldsUnset().WithMinRepeatedFieldsSize(1)` yields an error because the first method sets the maximum size to 0 and the later sets the minimum size to 1. Similarly, `WithMaxRepeatedFieldsSize(0).WithFieldsAlwaysSet()` yields an error. To address the issue, make sure `WithFields[AlwaysSet/Unset]` methods will overwrite `With[Min/Max]RepeatedFieldsSize` methods.

One of the consequences which is a little unexpected is that in the following, the maximum size will set to default and not to the user-provided value:

.WithMaxRepeatedFieldsSize(7).WithFieldsAlwaysSet()

PiperOrigin-RevId: 561642709

doc/domains-reference.md

diff --git a/doc/domains-reference.md b/doc/domains-reference.md
index 0d75c71..88885f0 100644
--- a/doc/domains-reference.md
+++ b/doc/domains-reference.md
@@ -510,6 +510,11 @@
   );
 ```
 
+Warning: `With[Repeated]Fields[Unset|AlwaysSet]` will overwrite previous
+`WithRepeatedFields[Min|Max]?Size` for a given field. For example, in the
+following code, the repeated fields can have any size other than zero:
+`Arbitrary<MyProto>().WithRepeatedFieldsMinSize(2).WithRepeatedFieldsSize(2).WithFieldsAlwaysSet()`
+
 Notice that `With[Optional|Repeated]Fields[Unset|AlwaysSet]` and
 `WithRepeatedFields[Min|Max]?Size` work recursively and apply to subprotos as
 well, unless subproto domains are explicitly defined. Also, calling

domain_tests/arbitrary_domains_test.cc

diff --git a/domain_tests/arbitrary_domains_test.cc b/domain_tests/arbitrary_domains_test.cc
index d78f2bf..a165abb 100644
--- a/domain_tests/arbitrary_domains_test.cc
+++ b/domain_tests/arbitrary_domains_test.cc
@@ -770,6 +770,27 @@
                   R"(.* field rep_ext .* Invalid size: .+. Max size: 0)")));
 }
 
+TEST(ProtocolBuffer, WithFieldsAlwaysSetResetsWithMaxRepeatedFieldsSize) {
+  absl::BitGen bitgen;
+
+  Domain<TestProtobuf> domain =
+      Arbitrary<TestProtobuf>()
+          .WithFieldsUnset()
+          .WithRepeatedFieldsMaxSize(
+              [](const google::protobuf::FieldDescriptor* field) {
+                return field->name() == "rep_i32";
+              },
+              1)
+          .WithFieldsAlwaysSet();
+
+  EXPECT_THAT(GenerateInitialValues(domain, 1000),
+              Contains(ResultOf(
+                  [](const Value<Domain<TestProtobuf>>& val) {
+                    return val.user_value.rep_i32_size();
+                  },
+                  Gt(1))));
+}
+
 TEST(ProtocolBufferEnum, Arbitrary) {
   auto domain = Arbitrary<TestProtobuf_Enum>();
   absl::BitGen bitgen;

fuzztest/internal/domains/container_of_impl.h

diff --git a/fuzztest/internal/domains/container_of_impl.h b/fuzztest/internal/domains/container_of_impl.h
index 8e94f50..8b1a2a3 100644
--- a/fuzztest/internal/domains/container_of_impl.h
+++ b/fuzztest/internal/domains/container_of_impl.h
@@ -44,6 +44,9 @@
 // Used for ChoosePosition();
 enum class IncludeEnd { kYes, kNo };
 
+// Default maximum size for FuzzTest containers/lists.
+inline constexpr size_t kDefaultContainerMaxSize = 1000;
+
 // For cases where the type is a container, choose one of the elements in the
 // container.
 template <typename Container>
@@ -359,8 +362,7 @@
 
   size_t min_size() const { return min_size_; }
   size_t max_size() const {
-    static constexpr size_t kDefaultMaxSize = 1000;
-    return max_size_.value_or(std::max(min_size_, kDefaultMaxSize));
+    return max_size_.value_or(std::max(min_size_, kDefaultContainerMaxSize));
   }
 
  private:

fuzztest/internal/domains/protobuf_domain_impl.h

diff --git a/fuzztest/internal/domains/protobuf_domain_impl.h b/fuzztest/internal/domains/protobuf_domain_impl.h
index 89c22ac..6ce5dff 100644
--- a/fuzztest/internal/domains/protobuf_domain_impl.h
+++ b/fuzztest/internal/domains/protobuf_domain_impl.h
@@ -233,9 +233,16 @@
     if (optional_policy == OptionalPolicy::kAlwaysNull) {
       max_repeated_fields_sizes_.push_back(
           {.filter = And(IsRepeated<FieldDescriptor>(), filter), .value = 0});
+      min_repeated_fields_sizes_.push_back(
+          {.filter = And(IsRepeated<FieldDescriptor>(), filter), .value = 0});
     } else if (optional_policy == OptionalPolicy::kWithoutNull) {
+      // TODO(b/298168054): Ideally, min/max should get updated only if the
+      // fields are not already always set.
       min_repeated_fields_sizes_.push_back(
           {.filter = And(IsRepeated<FieldDescriptor>(), filter), .value = 1});
+      max_repeated_fields_sizes_.push_back(
+          {.filter = And(IsRepeated<FieldDescriptor>(), filter),
+           .value = fuzztest::internal::kDefaultContainerMaxSize});
     }
     optional_policies_.push_back(
         {.filter = std::move(filter), .value = optional_policy});