[test] Move impl_or_verify! tests to doctests

They require a lot of fragile machinery as UI tests, and are much
simpler as doc tests.

gherrit-pr-id: G793f61a136b912fbd5ee4315cdea7cf3cf3cf8fb

Author: joshlf

src/doctests.rs

@@ -149,3 +149,20 @@ enum TransmuteRefMutDstOffsetNotMultiple {}
 /// let _: &mut SliceDst<(), [u8; 2]> = zerocopy::transmute_mut!(src);
 /// ```
 enum TransmuteRefMutDstElemSizeNotMultiple {}
+
+/// ```compile_fail,E0277
+/// use zerocopy::*;
+///
+/// #[derive(FromBytes, IntoBytes, Unaligned)]
+/// #[repr(transparent)]
+/// struct Foo<T>(T);
+///
+/// const _: () = unsafe {
+///     impl_or_verify!(T => TryFromBytes for Foo<T>);
+///     impl_or_verify!(T => FromZeros for Foo<T>);
+///     impl_or_verify!(T => FromBytes for Foo<T>);
+///     impl_or_verify!(T => IntoBytes for Foo<T>);
+///     impl_or_verify!(T => Unaligned for Foo<T>);
+/// };
+/// ```
+enum InvalidImplOrVerify {}

src/util/macros.rs

@@ -322,6 +322,9 @@ macro_rules! opt_unsafe_fn {
     ($($args:ident),* -> $ret:ident) => { Option<unsafe fn($($args),*) -> $ret> };
 }
 
+// This `allow` is needed because, when testing, we export this macro so it can
+// be used in `doctests`.
+#[allow(rustdoc::private_intra_doc_links)]
 /// Implements trait(s) for a type or verifies the given implementation by
 /// referencing an existing (derived) implementation.
 ///
@@ -342,8 +345,7 @@ macro_rules! opt_unsafe_fn {
 /// `const _: () = unsafe` macro). The reason for this restriction is that,
 /// while `impl_or_verify!` can guarantee that the provided impl is sound when
 /// it is compiled with the appropriate cfgs, there is no way to guarantee that
-/// it is
-/// ever compiled with those cfgs. In particular, it would be possible to
+/// it is ever compiled with those cfgs. In particular, it would be possible to
 /// accidentally place an `impl_or_verify!` call in a context that is only ever
 /// compiled when the `derive` feature is disabled. If that were to happen,
 /// there would be nothing to prevent an unsound trait impl from being emitted.
@@ -372,6 +374,7 @@ macro_rules! opt_unsafe_fn {
 ///     impl_or_verify!(T: Unaligned => Unaligned for Wrapper<T>);
 /// }
 /// ```
+#[cfg_attr(__ZEROCOPY_INTERNAL_USE_ONLY_DEV_MODE, macro_export)] // Used in `doctests.rs`
 macro_rules! impl_or_verify {
     // The following two match arms follow the same pattern as their
     // counterparts in `unsafe_impl!`; see the documentation on those arms for

tests/trybuild.rs

@@ -37,19 +37,3 @@ fn ui() {
     let t = trybuild::TestCases::new();
     t.compile_fail(format!("tests/{}/*.rs", source_files_dirname));
 }
-
-#[test]
-#[cfg_attr(miri, ignore)]
-fn ui_invalid_impls() {
-    let version = ToolchainVersion::extract_from_pwd().unwrap();
-    // See the doc comment on this method for an explanation of what this does
-    // and why we store source files in different directories.
-    let source_files_dirname = version.get_ui_source_files_dirname_and_maybe_print_warning();
-
-    // Set `-Wwarnings` in the `RUSTFLAGS` environment variable to ensure that
-    // `.stderr` files reflect what the typical user would encounter.
-    set_rustflags_w_warnings();
-
-    let t = trybuild::TestCases::new();
-    t.compile_fail(format!("tests/{}/invalid-impls/*.rs", source_files_dirname));
-}