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[SR-11559] Iterating over ClosedRange<Character> crashes the compiler #53964

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ole opened this issue Oct 2, 2019 · 6 comments
Closed

[SR-11559] Iterating over ClosedRange<Character> crashes the compiler #53964

ole opened this issue Oct 2, 2019 · 6 comments
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@ole
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself crash Bug: A crash, i.e., an abnormal termination of software type checker Area → compiler: Semantic analysis

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@ole
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ole commented Oct 2, 2019

Previous ID SR-11559
Radar rdar://problem/55987389
Original Reporter @ole
Type Bug
Status Closed
Resolution Done
Environment

I'm using the Swift that's part of Xcode 11.1 GM seed (11A1027) on macOS 10.15 Developer Beta 10.

$ swift --version
Apple Swift version 5.1 (swiftlang-1100.0.270.13 clang-1100.0.33.7)
Target: x86_64-apple-darwin19.0.0

I haven't tested this on the current master branch.

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

md5: 9ed2a900fe6fda0b29edeb0e0e2f4d73

Issue Description:

This (invalid) code crashes the compiler:

// main.swift
let a: Character = "a"
let z: Character = "z"
let charRange = a...z
for c in charRange {
    print(c)
}
$ swift main.swift
Stack dump:
0.  Program arguments: /Applications/Xcode-11.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -interpret main.swift -enable-objc-interop -sdk /Applications/Xcode-11.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -color-diagnostics -module-name main
1.  While type-checking statement at [main.swift:4:1 - line:6:1] RangeText="for c in charRange {
    print(c)
"
2.  While type-checking statement at [main.swift:4:1 - line:6:1] RangeText="for c in charRange {
    print(c)
"
3.  While type-checking expression at [main.swift:4:10 - line:4:10] RangeText=""
0  swift                    0x0000000105503eb3 PrintStackTraceSignalHandler(void*) + 51
1  swift                    0x0000000105503686 SignalHandler(int) + 358
2  libsystem_platform.dylib 0x00007fff69f4fb1d _sigtramp + 29
3  libsystem_platform.dylib 0x00007ffeeeb3c560 _sigtramp + 2227096160
4  swift                    0x0000000101bad136 swift::constraints::MissingConformance::diagnose(swift::Expr*, bool) const + 406
5  swift                    0x0000000101ae3994 swift::constraints::ConstraintSystem::applySolutionFixes(swift::Expr*, swift::constraints::Solution const&)::DiagnosticWalker::diagnose(swift::Expr*) + 260
6  swift                    0x0000000101ae3747 swift::constraints::ConstraintSystem::applySolutionFixes(swift::Expr*, swift::constraints::Solution const&)::DiagnosticWalker::walkToExprPost(swift::Expr*) + 23
7  swift                    0x0000000101c9191f swift::TypeChecker::typeCheckExpressionImpl(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener&, swift::constraints::ConstraintSystem*) + 2383
8  swift                    0x0000000101d3fbf1 swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 8241
9  swift                    0x0000000101d43e21 bool (anonymous namespace)::StmtChecker::typeCheckStmt<swift::Stmt>(swift::Stmt*&) + 129
10 swift                    0x0000000101d438b3 swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 23795
11 swift                    0x0000000101d3db61 bool (anonymous namespace)::StmtChecker::typeCheckStmt<swift::BraceStmt>(swift::BraceStmt*&) + 129
12 swift                    0x0000000101d46d67 swift::TypeChecker::typeCheckTopLevelCodeDecl(swift::TopLevelCodeDecl*) + 263
13 swift                    0x0000000101d62118 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int, unsigned int, unsigned int, unsigned int) + 1656
14 swift                    0x000000010145ce57 swift::CompilerInstance::performSemaUpTo(swift::SourceFile::ASTStage_t) + 4679
15 swift                    0x000000010115298f performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 815
16 swift                    0x000000010114ee54 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 6820
17 swift                    0x00000001010dc3c3 main + 1219
18 libdyld.dylib            0x00007fff69d4e405 start + 1
fish: 'swift main.swift' terminated by signal SIGSEGV (Address boundary error)

I would have expected a compiler error because charRange is not a Sequence so the for loop should not compile. Interestingly, that's exactly what I get when I remove the charRange variable and create the range directly in the for loop. This behaves correctly:

let a: Character = "a"
let z: Character = "z"
for c in a...z {
    print(c)
}
main.swift:3:11: error: operator function '...' requires that 'Character.Stride' conform to 'SignedInteger'
for c in a...z {
          ^
Swift.ClosedRange<τ_0_0>:1:11: note: requirement from conditional conformance of 'ClosedRange<Character>' to 'Sequence'
extension ClosedRange : Sequence where Bound : Strideable, Bound.Stride : SignedInteger {
          ^
main.swift:3:11: error: operator function '...' requires that 'Character' conform to 'Strideable'
for c in a...z {
          ^
Swift.ClosedRange<τ_0_0>:1:11: note: requirement from conditional conformance of 'ClosedRange<Character>' to 'Sequence'
extension ClosedRange : Sequence where Bound : Strideable, Bound.Stride : SignedInteger {
@belkadan
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belkadan commented Oct 2, 2019

I get basically the same failure on master. Thanks for reporting!

@swift-ci create

@LucianoPAlmeida
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@belkadan Is someone working on this already? If not can I give it a try if it is still not fixed? 🙂

@belkadan
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I don't think anyone's made particular progress. I have no idea what the fix is going to be but @hborla and @xedin should be able to help some!*

* note that I didn't check with them to see if they're currently busy with other things, so if they don't respond right away it's my fault

@hborla
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hborla commented Oct 25, 2019

@xedin recently added a tailored diagnostic for for-in sequence failures, so this might be fixed, as it should no longer be diagnosed through the MissingConformance constraint fix, but rather the ContextualMismatch fix. I don't have those changes locally though, so I'll let Pavel answer that!

@xedin
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xedin commented Oct 25, 2019

This problem has indeed been addressed by the changes @hborla mentioned and would produce a diagnostic:

error: protocol 'Sequence' requires that 'Character' conform to 'Strideable'
for c in charRange {
         ^
swift/stdlib/public/core/ClosedRange.swift:123:1: note: requirement from conditional conformance of 'ClosedRange<Character>' to 'Sequence'
extension ClosedRange: Sequence
^

Please use @ole please use the next available nightly build to verify and close.

@ole
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ole commented Oct 26, 2019

@xedin I can confirm that this is fixed in DEVELOPMENT-SNAPSHOT-2019-10-24-a. Thanks a lot everyone!

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
@AnthonyLatsis AnthonyLatsis added the crash Bug: A crash, i.e., an abnormal termination of software label Dec 12, 2022
This issue was closed.
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself crash Bug: A crash, i.e., an abnormal termination of software type checker Area → compiler: Semantic analysis
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@ole @xedin @belkadan @LucianoPAlmeida @hborla @AnthonyLatsis