Aliases to arrays are not automatically exempt from roundtrip tests.

[mbyx]

ctest gathers all public aliases to subject them to a number of tests, including roundtrip tests, however according to the documentation the roundtrip tests are not supported by aliases to arrays and must be manually skipped.

However when iterating through filtered aliases for the roundtrip test, we have access to the aliased type and can easily check if it is an array and skip it automatically.

[tgross35]

Cc #4696, the errors look like this:

  cargo:warning=/checkout/target/powerpc64-unknown-linux-gnu/debug/build/libc-test-59633f7226d066fc/out/ctest_output.c:69714:24: error: 'ctest_roundtrip__gregset_t' declared as function returning an array
  cargo:warning=69714 | CTEST_EXTERN gregset_t ctest_roundtrip__gregset_t(
  cargo:warning=      |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~
  cargo:warning=/checkout/target/powerpc64-unknown-linux-gnu/debug/build/libc-test-59633f7226d066fc/out/ctest_output.c: In function 'ctest_roundtrip__gregset_t':
  cargo:warning=/checkout/target/powerpc64-unknown-linux-gnu/debug/build/libc-test-59633f7226d066fc/out/ctest_output.c:69735:12: error: returning 'long unsigned int *' from a function with return type 'int' makes integer from pointer without a cast [-Wint-conversion]
  cargo:warning=69735 |     return value;
  cargo:warning=      |            ^~~~~
  cargo:warning=/checkout/target/powerpc64-unknown-linux-gnu/debug/build/libc-test-59633f7226d066fc/out/ctest_output.c: At top level:
  cargo:warning=/checkout/target/powerpc64-unknown-linux-gnu/debug/build/libc-test-59633f7226d066fc/out/ctest_output.c:69741:25: error: 'ctest_roundtrip__fpregset_t' declared as function returning an array
  cargo:warning=69741 | CTEST_EXTERN fpregset_t ctest_roundtrip__fpregset_t(
  cargo:warning=      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
  cargo:warning=/checkout/target/powerpc64-unknown-linux-gnu/debug/build/libc-test-59633f7226d066fc/out/ctest_output.c: In function 'ctest_roundtrip__fpregset_t':
  cargo:warning=/checkout/target/powerpc64-unknown-linux-gnu/debug/build/libc-test-59633f7226d066fc/out/ctest_output.c:69762:12: error: returning 'double *' from a function with return type 'int' makes integer from pointer without a cast [-Wint-conversion]
  cargo:warning=69762 |     return value;
  cargo:warning=      |            ^~~~~
  cargo:warning=At top level:
  cargo:warning=cc1: note: unrecognized command-line option '-Wno-unknown-warning-option' may have been intended to silence earlier diagnostics