Fix problems around unexpected_cfgs

Cargo.toml

@@ -35,6 +35,10 @@ unused_import_braces = "warn"
 variant_size_differences = "warn"
 # Unsafe code is needed for array initialization using MaybeUninit.
 # unsafe_code = "forbid"
+# FIXME: For tarpaulin some code is excluded, since tarpaulin does not detect the line coverage well
+# Statements like: #![cfg(not(tarpaulin_include))]
+# but the lint doesn't like them and it is probably better to not have a build.rs just for that.
+unexpected_cfgs = "allow"
 
 [workspace.lints.clippy]
 # These lints have false positives and are disabled until they are fixed.

serde_with/src/guide/serde_as.md

@@ -144,7 +144,7 @@ Our goal is to serialize this `Data` struct.
 Currently, we do not have anything we can use to replace `???` with, since `_` only works if `RemoteType` would implement `Serialize`, which it does not.
 
 ```rust
-# #[cfg(FALSE)] {
+# #[cfg(any())] {
 #[serde_as]
 #[derive(serde::Serialize)]
 struct Data {
@@ -159,7 +159,7 @@ The `SerializeAs` implementation is **always** written for a local type.
 This allows it to seamlessly work with types from dependencies without running into orphan rule problems.
 
 ```rust
-# #[cfg(FALSE)] {
+# #[cfg(any())] {
 struct LocalType;
 
 impl SerializeAs<RemoteType> for LocalType {
@@ -188,7 +188,7 @@ As can be seen, this is mostly boilerplate, since the most part is encapsulated
 The final `Data` struct will now look like:
 
 ```rust
-# #[cfg(FALSE)] {
+# #[cfg(any())] {
 #[serde_as]
 #[derive(serde::Serialize)]
 struct Data {
@@ -205,7 +205,7 @@ This is a special functionality of serde, where it derives the de/serialization
 You can find all the details in the [official serde documentation](https://serde.rs/remote-derive.html).
 
 ```rust
-# #[cfg(FALSE)] {
+# #[cfg(any())] {
 // Pretend that this is somebody else's crate, not a module.
 mod other_crate {
     // Neither Serde nor the other crate provides Serialize and Deserialize
@@ -238,7 +238,7 @@ We can write this implementation.
 The implementation for `DeserializeAs` works analogue.
 
 ```rust
-# #[cfg(FALSE)] {
+# #[cfg(any())] {
 impl SerializeAs<Duration> for DurationDef {
     fn serialize_as<S>(value: &Duration, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -253,7 +253,7 @@ impl SerializeAs<Duration> for DurationDef {
 This now allows us to use `Duration` for serialization.
 
 ```rust
-# #[cfg(FALSE)] {
+# #[cfg(any())] {
 use other_crate::Duration;
 
 #[serde_as]

serde_with/src/lib.rs

@@ -1767,7 +1767,7 @@ pub struct PickFirst<T>(PhantomData<T>);
 /// Deserializing works analogue, by deserializing a `T` and then converting into `O`.
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// struct S {
 ///     #[serde_as(as = "FromInto<T>")]
 ///     value: O,
@@ -1849,7 +1849,7 @@ pub struct FromInto<T>(PhantomData<T>);
 /// Deserializing works analogue, by deserializing a `T` and then converting into `O`.
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// struct S {
 ///     #[serde_as(as = "FromIntoRef<T>")]
 ///     value: O,
@@ -1930,7 +1930,7 @@ pub struct FromIntoRef<T>(PhantomData<T>);
 /// Deserializing works analogue, by deserializing a `T` and then converting into `O`.
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// struct S {
 ///     #[serde_as(as = "TryFromInto<T>")]
 ///     value: O,
@@ -2019,7 +2019,7 @@ pub struct TryFromInto<T>(PhantomData<T>);
 /// Deserializing works analogue, by deserializing a `T` and then converting into `O`.
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// struct S {
 ///     #[serde_as(as = "TryFromIntoRef<T>")]
 ///     value: O,

serde_with/src/rust.rs

@@ -18,7 +18,7 @@ use crate::prelude::*;
 /// This cannot work, since there is no way to tell the `Vec` to skip the inner `DoubleOption` if it is `None`.
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// # struct Foobar {
 /// #[serde_as(as = "Vec<DoubleOption<_>>")]
 /// data: Vec<Option<Option<i32>>>,
@@ -184,7 +184,7 @@ pub mod unwrap_or_skip {
 /// The `_` is a placeholder which works for any type which implements [`Serialize`]/[`Deserialize`].
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// #[serde_as]
 /// #[derive(Deserialize, Serialize)]
 /// struct A {
@@ -300,7 +300,7 @@ pub mod sets_duplicate_value_is_error {
 /// The `_` is a placeholder which works for any type which implements [`Serialize`]/[`Deserialize`].
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// #[serde_as]
 /// #[derive(Deserialize, Serialize)]
 /// struct A {
@@ -420,7 +420,7 @@ pub mod maps_duplicate_key_is_error {
 /// The `_` is a placeholder which works for any type which implements [`Serialize`]/[`Deserialize`].
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// #[serde_as]
 /// #[derive(Deserialize, Serialize)]
 /// struct A {
@@ -508,7 +508,7 @@ pub mod sets_last_value_wins {
 /// The `_` is a placeholder which works for any type which implements [`Serialize`]/[`Deserialize`].
 ///
 /// ```rust
-/// # #[cfg(FALSE)] {
+/// # #[cfg(any())] {
 /// #[serde_as]
 /// #[derive(Deserialize, Serialize)]
 /// struct A {