Fix crash during type checking when adding members to an extension.

[rudkx]

What's in this pull request?

Cherry-picking a fix from master to the swift-3.0-branch.

Resolved bug number: (rdar://problem/27671033)

---

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• Test pull request on Swift continuous integration.

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If the extension ended up with ErrorType, we could crash while we
continue trying to process its body adding members.

Just bail out in this case.

rdar://problem/27671033

(code cherry picked from commit c9ec7e3)
(test cherry picked from commit 107d602)

[rudkx]

@swift-ci Test.

[rudkx]

@DougGregor Can you review for the swift-3.0-branch?

[DougGregor]

LGTM!

[DougGregor]

@shahmishal the Linux failure is a problem on the builder:

14:27:37 Building remotely on Ubuntu-14.04-2 (Ubuntu-14.04) in workspace /home/buildnode/jenkins/workspace/swift-PR-Linux@2
14:27:37 > git rev-parse --is-inside-work-tree # timeout=10
14:27:37 Fetching changes from the remote Git repository
14:27:37 > git config remote.origin.url [email protected]:apple/swift.git # timeout=10
14:27:37 ERROR: Error fetching remote repo 'origin'
14:27:37 hudson.plugins.git.GitException: Failed to fetch from [email protected]:apple/swift.git
14:27:37 at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:763)
14:27:37 at hudson.plugins.git.GitSCM.retrieveChanges(GitSCM.java:1012)
14:27:37 at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1043)
14:27:37 at org.jenkinsci.plugins.multiplescms.MultiSCM.checkout(MultiSCM.java:129)
14:27:37 at hudson.scm.SCM.checkout(SCM.java:485)
14:27:37 at hudson.model.AbstractProject.checkout(AbstractProject.java:1276)
14:27:37 at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:607)
14:27:37 at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:86)
14:27:37 at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:529)
14:27:37 at hudson.model.Run.execute(Run.java:1738)
14:27:37 at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
14:27:37 at hudson.model.ResourceController.execute(ResourceController.java:98)
14:27:37 at hudson.model.Executor.run(Executor.java:410)
14:27:37 Caused by: hudson.plugins.git.GitException: Command "git config remote.origin.url [email protected]:apple/swift.git" returned status code 4:
14:27:37 stdout:
14:27:37
stderr: error: failed to write new configuration file .git/config.lock
14:27:37

[DougGregor]

@swift-ci please test Linux