[swiftc (54 vs. 5456)] Add crasher in swift::TypeBase::getCanonicalType(...)

[practicalswift]

Add test case for crash triggered in swift::TypeBase::getCanonicalType(...).

Current number of unresolved compiler crashers: 54 (5456 resolved)

Assertion failure in include/swift/AST/Type.h (line 369):

Assertion `isActuallyCanonicalOrNull() && "Forming a CanType out of a non-canonical type!"' failed.

When executing: swift::CanType::CanType(swift::TypeBase *)

Assertion context:

  static ClassDecl *getClassBoundImpl(CanType type);

public:
  explicit CanType(TypeBase *P = 0) : Type(P) {
    assert(isActuallyCanonicalOrNull() &&
           "Forming a CanType out of a non-canonical type!");
  }
  explicit CanType(Type T) : Type(T) {
    assert(isActuallyCanonicalOrNull() &&
           "Forming a CanType out of a non-canonical type!");
  }

Stack trace:

0 0x00000000038f7328 llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/path/to/swift/bin/swift+0x38f7328)
1 0x00000000038f7a66 SignalHandler(int) (/path/to/swift/bin/swift+0x38f7a66)
2 0x00007fa7f792a3e0 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x113e0)
3 0x00007fa7f6290428 gsignal /build/glibc-Qz8a69/glibc-2.23/signal/../sysdeps/unix/sysv/linux/raise.c:54:0
4 0x00007fa7f629202a abort /build/glibc-Qz8a69/glibc-2.23/stdlib/abort.c:91:0
5 0x00007fa7f6288bd7 __assert_fail_base /build/glibc-Qz8a69/glibc-2.23/assert/assert.c:92:0
6 0x00007fa7f6288c82 (/lib/x86_64-linux-gnu/libc.so.6+0x2dc82)
7 0x000000000144b949 swift::TypeBase::getCanonicalType() (/path/to/swift/bin/swift+0x144b949)
8 0x0000000001298280 (anonymous namespace)::FindCapturedVars::checkType(swift::Type, swift::SourceLoc) (/path/to/swift/bin/swift+0x1298280)
9 0x00000000012986ea (anonymous namespace)::FindCapturedVars::walkToExprPre(swift::Expr*) (/path/to/swift/bin/swift+0x12986ea)
10 0x00000000013b9b5e swift::ASTVisitor<(anonymous namespace)::Traversal, swift::Expr*, swift::Stmt*, bool, swift::Pattern*, bool, void>::visit(swift::Expr*) (/path/to/swift/bin/swift+0x13b9b5e)
11 0x00000000013b892b swift::Expr::walk(swift::ASTWalker&) (/path/to/swift/bin/swift+0x13b892b)
12 0x0000000001299700 (anonymous namespace)::FindCapturedVars::walkToDeclPre(swift::Decl*) (/path/to/swift/bin/swift+0x1299700)
13 0x00000000013b8e24 (anonymous namespace)::Traversal::doIt(swift::Decl*) (/path/to/swift/bin/swift+0x13b8e24)
14 0x00000000013bc058 swift::ASTVisitor<(anonymous namespace)::Traversal, swift::Expr*, swift::Stmt*, bool, swift::Pattern*, bool, void>::visit(swift::Stmt*) (/path/to/swift/bin/swift+0x13bc058)
15 0x00000000013b89ae swift::Stmt::walk(swift::ASTWalker&) (/path/to/swift/bin/swift+0x13b89ae)
16 0x0000000001297481 swift::TypeChecker::computeCaptures(swift::AnyFunctionRef) (/path/to/swift/bin/swift+0x1297481)
17 0x00000000011cc64b typeCheckFunctionsAndExternalDecls(swift::TypeChecker&) (/path/to/swift/bin/swift+0x11cc64b)
18 0x00000000011cce98 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int) (/path/to/swift/bin/swift+0x11cce98)
19 0x0000000000f21846 swift::CompilerInstance::performSema() (/path/to/swift/bin/swift+0xf21846)
20 0x00000000004a51d6 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) (/path/to/swift/bin/swift+0x4a51d6)
21 0x0000000000464337 main (/path/to/swift/bin/swift+0x464337)
22 0x00007fa7f627b830 __libc_start_main /build/glibc-Qz8a69/glibc-2.23/csu/../csu/libc-start.c:325:0
23 0x00000000004619d9 _start (/path/to/swift/bin/swift+0x4619d9)

[practicalswift]

@swift-ci please test and merge