Fix compilation errors in generated code.

Bug: 270547306
Test: m rust
Test: atest sysprop_test
Change-Id: I74b4570a9d58521bf2cbc9a09fe7a457a302d8e5

RustGen.cpp

diff --git a/RustGen.cpp b/RustGen.cpp
index a1e7314..0494ece 100644
--- a/RustGen.cpp
+++ b/RustGen.cpp
@@ -353,6 +353,7 @@
       auto enum_type = GetRustEnumType(prop);
       auto values = ParseEnumValues(prop.enum_values());
 
+      writer.Write("#[allow(missing_docs)]\n");
       writer.Write(
           "#[derive(Copy, Clone, Debug, Eq, "
           "PartialEq, PartialOrd, Hash, Ord)]\n");
@@ -398,7 +399,6 @@
         writer.Write("%s::%s => write!(f, \"%s\"),\n", enum_type.c_str(),
                      SnakeCaseToCamelCase(value).c_str(), value.c_str());
       }
-      writer.Write("_ => Err(fmt::Error),\n");
       writer.Dedent();
       writer.Write("}\n");
       writer.Dedent();

tests/RustGenTest.cpp

diff --git a/tests/RustGenTest.cpp b/tests/RustGenTest.cpp
index fdddf93..79c088f 100644
--- a/tests/RustGenTest.cpp
+++ b/tests/RustGenTest.cpp
@@ -326,6 +326,7 @@
     }
 }
 
+#[allow(missing_docs)]
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Hash, Ord)]
 pub enum TestEnumValues {
     A,
@@ -364,7 +365,6 @@
             TestEnumValues::E => write!(f, "e"),
             TestEnumValues::F => write!(f, "f"),
             TestEnumValues::G => write!(f, "G"),
-            _ => Err(fmt::Error),
         }
     }
 }
@@ -467,6 +467,7 @@
     system_properties::write("test_strlist", value.as_str()).map_err(SysPropError::SetError)
 }
 
+#[allow(missing_docs)]
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Hash, Ord)]
 pub enum ElValues {
     Enu,
@@ -493,7 +494,6 @@
             ElValues::Enu => write!(f, "enu"),
             ElValues::Mva => write!(f, "mva"),
             ElValues::Lue => write!(f, "lue"),
-            _ => Err(fmt::Error),
         }
     }
 }