Build fails on macOS in Travis CI with 3.0.0 preview 7 - "dyld: lazy symbol binding failed: Symbol not found: _utimensat"

[martincostello]

I've been maintaining a branch of AspNet.Security.OpenId.Providers for ASP.NET Core 3.0 for a while, and just updated it from preview 6 to preview 7 (SDK version 3.0.100-preview7-012821).

The macOS build in Travis CI fails with the following error in preview 7 (build):

dyld: lazy symbol binding failed: Symbol not found: _utimensat
  Referenced from: /Users/travis/build/aspnet-contrib/AspNet.Security.OpenId.Providers/.dotnetcli/shared/Microsoft.NETCore.App/3.0.0-preview7-27912-14/System.Native.dylib
  Expected in: /usr/lib/libSystem.B.dylib

This failure appears right at the top of the build script with dotnet build.

I've already updated several other branches from preview 6 to preview 7 with no issue, so it doesn't look like something systematic, but I'm not sure what specifically in this PR is causing the problem.

[martincostello]

Same issue for this PR too on macOS.

[martincostello]

Further digging found that the Travis macOS build was pinned to osx_image: xcode8.3, which equates to macOS 10.12 (docs).

Removing this constraint (aspnet-contrib/AspNet.Security.OAuth.Providers@dbd0a96) fixed the issue.

Leaving open for now as I'm not sure if this is an intentional change to the compatibility matrix for .NET Core 3.0 or not.

[ericstj]

Introduced in dotnet/corefx#31522 /cc @Anipik @bartonjs @stephentoub

Did we intend to drop support for OSX 10.12? Our docs say its still supported.
https://docs.microsoft.com/en-US/dotnet/core/macos-prerequisites?tabs=netcore30

[bartonjs]

macOS 10.12 is not supported: https://github.com/dotnet/core/blob/master/release-notes/3.0/3.0-supported-os.md. We just have too many redundant documentation sources. (@leecow we need to get https://docs.microsoft.com/en-US/dotnet/core/macos-prerequisites?tabs=netcore30 updated to say 10.13)

[danmoseley]

Doc fixed. Thanks for the report.