[SR-11085] Sema crash: These contextual type purposes cannot fail with a conversion type specified

[rxwei]

Previous ID	SR-11085
Radar	rdar://problem/56144412
Original Reporter	@rxwei
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, CompilerCrash, TypeChecker
Assignee	@hamishknight
Priority	Medium

md5: b71a9600d6cf35f0af6bc90c1b69bdd5

Issue Description:

Sema crashes on the following code. While #line definitely does not have type String, the compiler should not crash.

func foo(x: Int) {}
func foo(line: String = #line) {}
foo()

➜  Desktop swiftc defaultargs.swift
These contextual type purposes cannot fail with a conversion type specified!
UNREACHABLE executed at /Users/buildnode/jenkins/workspace/oss-swift-package-osx/swift/lib/Sema/CSDiag.cpp:2068!
Stack dump:
0.  Program arguments: /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2019-07-03-a.xctoolchain/usr/bin/swift -frontend -c -primary-file defaultargs.swift -target x86_64-apple-darwin18.6.0 -enable-objc-interop -sdk /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -color-diagnostics -module-name defaultargs -o /var/folders/b1/qdyl0rys4q7d4fcxbjn78rhc00h255/T/defaultargs-2bdfb6.o
1.  Apple Swift version 5.1-dev (LLVM 8d110eebee, Swift 8221c6735c)
2.  While type-checking statement at [defaultargs.swift:3:1 - line:3:5] RangeText="foo("
3.  While type-checking expression at [defaultargs.swift:3:1 - line:3:5] RangeText="foo("
4.  While type-checking expression at [defaultargs.swift:3:4 - line:3:4] RangeText=""
0  swift                    0x000000010d34bc95 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 37
1  swift                    0x000000010d34af85 llvm::sys::RunSignalHandlers() + 85
2  swift                    0x000000010d34c278 SignalHandler(int) + 264
3  libsystem_platform.dylib 0x00007fff63a92b5d _sigtramp + 29
4  libsystem_platform.dylib 0x0000000000000052 _sigtramp + 2622936338
5  libsystem_c.dylib        0x00007fff6394c6a6 abort + 127
6  swift                    0x000000010e45b21e llvm::llvm_unreachable_internal(char const*, char const*, unsigned int) + 462
7  swift                    0x000000010a383cd6 (anonymous namespace)::FailureDiagnosis::diagnoseContextualConversionError(swift::Expr*, swift::Type, swift::ContextualTypePurpose, swift::Type) + 8790
8  swift                    0x000000010a38004a swift::constraints::ConstraintSystem::diagnoseFailureForExpr(swift::Expr*) + 122
9  swift                    0x000000010a430a67 swift::constraints::ConstraintSystem::salvage(llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::Expr*) + 1303
10 swift                    0x000000010a3daf3c swift::constraints::ConstraintSystem::solve(swift::Expr*&, swift::Type, swift::ExprTypeCheckListener*, llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::FreeTypeVariableBinding) + 508
11 swift                    0x000000010a494ca4 swift::TypeChecker::typeCheckExpressionImpl(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener&, swift::constraints::ConstraintSystem*) + 964
12 swift                    0x000000010a495159 swift::TypeChecker::typeCheckParameterDefault(swift::Expr*&, swift::DeclContext*, swift::Type, bool, bool) + 281
13 swift                    0x000000010a374971 getCallerDefaultArg(swift::constraints::ConstraintSystem&, swift::DeclContext*, swift::SourceLoc, swift::ConcreteDeclRef&, unsigned int) + 849
14 swift                    0x000000010a3734b7 (anonymous namespace)::ExprRewriter::coerceCallArguments(swift::Expr*, swift::AnyFunctionType*, swift::ApplyExpr*, llvm::ArrayRef<swift::Identifier>, bool, swift::constraints::ConstraintLocatorBuilder) + 2279
15 swift                    0x000000010a363188 (anonymous namespace)::ExprRewriter::finishApply(swift::ApplyExpr*, swift::Type, swift::constraints::ConstraintLocatorBuilder) + 3832
16 swift                    0x000000010a375bdb (anonymous namespace)::ExprRewriter::visitApplyExpr(swift::ApplyExpr*) + 123
17 swift                    0x000000010a365876 (anonymous namespace)::ExprWalker::walkToExprPost(swift::Expr*) + 22
18 swift                    0x000000010a7788d3 swift::Expr::walk(swift::ASTWalker&) + 115
19 swift                    0x000000010a35c96c swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::Expr*, swift::Type, bool, bool) + 492
20 swift                    0x000000010a494d33 swift::TypeChecker::typeCheckExpressionImpl(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener&, swift::constraints::ConstraintSystem*) + 1107
21 swift                    0x000000010a4948cf swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem*) + 63
22 swift                    0x000000010a52d5aa swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 602
23 swift                    0x000000010a52c6d8 bool (anonymous namespace)::StmtChecker::typeCheckStmt<swift::BraceStmt>(swift::BraceStmt*&) + 136
24 swift                    0x000000010a52c7ce swift::TypeChecker::typeCheckTopLevelCodeDecl(swift::TopLevelCodeDecl*) + 174
25 swift                    0x000000010a54cbb2 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int, unsigned int, unsigned int, unsigned int) + 914
26 swift                    0x0000000109d078d6 swift::CompilerInstance::parseAndTypeCheckMainFileUpTo(swift::SourceFile::ASTStage_t, swift::PersistentParserState&, swift::DelayedParsingCallbacks*, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>) + 502
27 swift                    0x0000000109d066e6 swift::CompilerInstance::parseAndCheckTypesUpTo(swift::CompilerInstance::ImplicitImports const&, swift::SourceFile::ASTStage_t) + 342
28 swift                    0x0000000109d0608a swift::CompilerInstance::performSemaUpTo(swift::SourceFile::ASTStage_t) + 618
29 swift                    0x0000000109afaae2 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 1730
30 swift                    0x0000000109af94e2 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3026
31 swift                    0x0000000109aa1659 main + 729
32 libdyld.dylib            0x00007fff638a73d5 start + 1
<unknown>:0: error: unable to execute command: Abort trap: 6
<unknown>:0: error: compile command failed due to signal 6 (use -v to see invocation)

However, this works fine.

func foo() {}
func foo(line: String = #line) {}
foo()

[rxwei]

@xedin

[theblixguy]

PR: #26074

[theblixguy]

Fixed on master

[theblixguy]

Reopening this ticket because the fix was reverted due to causing a regression with generics type resolution (SR-11223).

[hamishknight]

@theblixguy Are you still working on this? If not, I'd like to try and have a crack at it using the request evaluator.

[theblixguy]

@hamishknight I am not, feel free to assign it to yourself!

[hamishknight]

Thanks!

[davezarzycki]

#28106

[hamishknight]

#28279

[hamishknight]

Fixed by #28279 @rxwei please verify using the next available master snapshot from https://swift.org/download/#snapshots.