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[SR-5422] Regression: Call to Optional flatMap/map segfault #47996

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stephencelis opened this issue Jul 10, 2017 · 7 comments
Closed

[SR-5422] Regression: Call to Optional flatMap/map segfault #47996

stephencelis opened this issue Jul 10, 2017 · 7 comments
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@stephencelis
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself type checker Area → compiler: Semantic analysis

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@stephencelis
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Previous ID SR-5422
Radar None
Original Reporter @stephencelis
Type Bug
Status Resolved
Resolution Done
Environment

Xcode 9 beta 3
(Some Xcode 8.3.3 issues noted, as well.)

Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, TypeChecker
Assignee @stephencelis
Priority Medium

md5: 69fb8bbd42d000a5ed52d2bd6b06b093

is blocked by:

  • SR-5251 Generic Sequence Function Compilation Fails

Issue Description:

The following causes a segfault in the type-checker:

extension Optional {
  public func apply<A>(_ f: ((Wrapped) -> A)?) -> A? {
    return self.flatMap { a in f.map { f in f(a) } }
  }
}

Trace:

0  swift                    0x00000001102317fa PrintStackTraceSignalHandler(void*) + 42
1  swift                    0x0000000110230c36 SignalHandler(int) + 662
2  libsystem_platform.dylib 0x00007fffb9a3eb3a _sigtramp + 26
3  libsystem_platform.dylib 0x00007fb8149f9ac0 _sigtramp + 1526443936
4  swift                    0x000000010db7b9e2 std::__1::__function::__func<(anonymous namespace)::FailureDiagnosis::diagnoseTrailingClosureErrors(swift::ApplyExpr*)::$_0, std::__1::allocator<(anonymous namespace)::FailureDiagnosis::diagnoseTrailingClosureErrors(swift::ApplyExpr*)::$_0>, bool (swift::Type, swift::Type)>::operator()(swift::Type&&, swift::Type&&) + 258
5  swift                    0x000000010db683dc (anonymous namespace)::FailureDiagnosis::diagnoseClosureExpr(swift::ClosureExpr*, swift::Type, std::__1::function<bool (swift::Type, swift::Type)>) + 1260
6  swift                    0x000000010db6d739 (anonymous namespace)::FailureDiagnosis::visitApplyExpr(swift::ApplyExpr*) + 14377
7  swift                    0x000000010db499b9 swift::constraints::ConstraintSystem::diagnoseFailureForExpr(swift::Expr*) + 73
8  swift                    0x000000010db7ecf7 swift::constraints::ConstraintSystem::salvage(llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::Expr*) + 6199
9  swift                    0x000000010dc471aa swift::TypeChecker::solveForExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::FreeTypeVariableBinding, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem&, llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 8858
10 swift                    0x000000010dc4aed4 swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem*) + 692
11 swift                    0x000000010db5965b (anonymous namespace)::FailureDiagnosis::typeCheckChildIndependently(swift::Expr*, swift::Type, swift::ContextualTypePurpose, swift::OptionSet<TCCFlags, unsigned int>, swift::ExprTypeCheckListener*, bool) + 1963
12 swift                    0x000000010db683a0 (anonymous namespace)::FailureDiagnosis::diagnoseClosureExpr(swift::ClosureExpr*, swift::Type, std::__1::function<bool (swift::Type, swift::Type)>) + 1200
13 swift                    0x000000010db6d739 (anonymous namespace)::FailureDiagnosis::visitApplyExpr(swift::ApplyExpr*) + 14377
14 swift                    0x000000010db499b9 swift::constraints::ConstraintSystem::diagnoseFailureForExpr(swift::Expr*) + 73
15 swift                    0x000000010db7ecf7 swift::constraints::ConstraintSystem::salvage(llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::Expr*) + 6199
16 swift                    0x000000010dc471aa swift::TypeChecker::solveForExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::FreeTypeVariableBinding, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem&, llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 8858
17 swift                    0x000000010dc4aed4 swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem*) + 692
18 swift                    0x000000010dcce744 swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 7764
19 swift                    0x000000010dccfe18 swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 13608
20 swift                    0x000000010dccbcd8 swift::TypeChecker::typeCheckAbstractFunctionBodyUntil(swift::AbstractFunctionDecl*, swift::SourceLoc) + 1128
21 swift                    0x000000010dcd169b swift::TypeChecker::typeCheckAbstractFunctionBody(swift::AbstractFunctionDecl*) + 475
22 swift                    0x000000010dcef59a swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int, unsigned int, unsigned int) + 2490
23 swift                    0x000000010d825fa7 swift::CompilerInstance::performSema() + 5031
24 swift                    0x000000010cbb93b8 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 1384
25 swift                    0x000000010cbb75e4 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 7332
26 swift                    0x000000010cb6cee8 main + 12248
27 libdyld.dylib            0x00007fffb982f235 start + 1
Stack dump:
0.  Program arguments: /Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c /Users/stephencelis/Desktop/SwiftBug/SwiftBug/ViewController.swift /Users/stephencelis/Desktop/SwiftBug/SwiftBug/AppDelegate.swift -primary-file /Users/stephencelis/Desktop/SwiftBug/SwiftBug/Apply.swift -target x86_64-apple-ios11.0 -enable-objc-interop -sdk /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator11.0.sdk -I /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Products/Debug-iphonesimulator -F /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Products/Debug-iphonesimulator -enable-testing -g -module-cache-path /Users/stephencelis/Library/Developer/Xcode/DerivedData/ModuleCache -swift-version 4 -enforce-exclusivity=checked -D DEBUG -serialize-debugging-options -Xcc -I/Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/swift-overrides.hmap -Xcc -iquote -Xcc /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/SwiftBug-generated-files.hmap -Xcc -I/Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/SwiftBug-own-target-headers.hmap -Xcc -I/Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/SwiftBug-all-target-headers.hmap -Xcc -iquote -Xcc /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/SwiftBug-project-headers.hmap -Xcc -I/Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Products/Debug-iphonesimulator/include -Xcc -I/Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/DerivedSources/x86_64 -Xcc -I/Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/DerivedSources -Xcc -DDEBUG=1 -Xcc -working-directory/Users/stephencelis/Desktop/SwiftBug -emit-module-doc-path /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/Objects-normal/x86_64/Apply~partial.swiftdoc -serialize-diagnostics-path /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/Objects-normal/x86_64/Apply.dia -Onone -module-name SwiftBug -emit-module-path /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/Objects-normal/x86_64/Apply~partial.swiftmodule -emit-dependencies-path /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/Objects-normal/x86_64/Apply.d -emit-reference-dependencies-path /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/Objects-normal/x86_64/Apply.swiftdeps -o /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Build/Intermediates.noindex/SwiftBug.build/Debug-iphonesimulator/SwiftBug.build/Objects-normal/x86_64/Apply.o -index-store-path /Users/stephencelis/Library/Developer/Xcode/DerivedData/SwiftBug-bftxexkemfqqtedqttuedtceftui/Index/DataStore -index-system-modules 
1.  While type-checking 'apply(_:)' at /Users/stephencelis/Desktop/SwiftBug/SwiftBug/Apply.swift:2:10
2.  While type-checking expression at [/Users/stephencelis/Desktop/SwiftBug/SwiftBug/Apply.swift:3:12 - line:3:54] RangeText="self.flatMap { a in f.map { f_ in f_(a) } }"
3.  While type-checking expression at [/Users/stephencelis/Desktop/SwiftBug/SwiftBug/Apply.swift:3:32 - line:3:52] RangeText="f.map { f_ in f_(a) }"

(This compiles fine in previous versions of Xcode.)

The flipped version doesn't segfault, but fails to compile:

extension Optional {
  public func apply<A>(_ f: ((Wrapped) -> A)?) -> A? {
    return f.flatMap { f in self.map { a in f(a) } }
  }
}

Invalid conversion from throwing function of type '((((Wrapped) -> A)) throws -> _?) throws -> _?' to non-throwing function type '((((Wrapped) -> A)) throws -> A?) -> A?'

Adopting a point-free style also fails to compile:

extension Optional {
  public func apply<A>(_ f: ((Wrapped) -> A)?) -> A? {
    return self.flatMap { f.map($0) }
  }
}

Invalid conversion from throwing function of type '((((Wrapped) -> A)) throws -> _?) throws -> _?' to non-throwing function type '((((Wrapped) -> A)) throws -> A?) -> A?'

(This also used to compile.)

Meanwhile:

extension Optional {
  public func apply<A>(_ f: ((Wrapped) -> A)?) -> A? {
    return self.flatMap { f.map($0) }
  }
}

Xcode 9:

Cannot convert value of type 'Wrapped' to expected argument type '(((_) -> _)) throws -> _'

Xcode 8.3.3:

generic parameter 'U' could not be inferred

And:

extension Optional {
  public func apply<A>(_ f: ((Wrapped) -> A)?) -> A? {
    return f.flatMap(self.map)
    // or return self.flatMap(f.map)
  }
}

Xcode 9:

'flatMap' produces 'U?', not the expected contextual result type '_?'

Xcode 8.3.3:

call can throw, but it is not marked with 'try' and the error is not handled
@stephencelis
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Related to https://bugs.swift.org/browse/SR-5251

@belkadan
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Does not crash but fails to compile on master. @xedin?

@xedin
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xedin commented Jul 11, 2017

I think this is related to #10881 which @rudkx just merged, and everything now compiles correctly on master.

@xedin
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xedin commented Jul 18, 2017

@stephencelis Please verify.

@stephencelis
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@xedin Big improvements! Most of these iterations compile, save for a couple that are giving throws diagnostics some issues:

return self.flatMap { f.map($0) }

Cannot convert value of type 'Wrapped' to expected argument type '(((_) -> _)) throws -> _'

return self.flatMap(f.map)

Call can throw, but it is not marked with 'try' and the error is not handled

@stephencelis
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(Should I reopen? Or post another issue highlighting these two issues?)

@xedin
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xedin commented Jul 25, 2017

@stephencelis Please open a separate issue for the examples you mentioned, that might be a different root cause...

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
This issue was closed.
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Labels
bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself type checker Area → compiler: Semantic analysis
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@stephencelis @xedin @belkadan