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[SR-11134] Missing comma not diagnosed resulting a runtime crash rather than compile time error #53530

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DevAndArtist mannequin opened this issue Jul 15, 2019 · 4 comments
Closed

[SR-11134] Missing comma not diagnosed resulting a runtime crash rather than compile time error #53530

DevAndArtist mannequin opened this issue Jul 15, 2019 · 4 comments
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@theblixguy
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself

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@DevAndArtist
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Mannequin

DevAndArtist mannequin commented Jul 15, 2019

Previous ID SR-11134
Radar None
Original Reporter @DevAndArtist
Type Bug
Status Resolved
Resolution Done
Environment

Apple Swift version 5.1 (swiftlang-1100.0.212.5 clang-1100.0.28.2)
Target: x86_64-apple-darwin19.0.0

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

md5: 800226d4c9df36713bd9fbf8b113f1ac

Issue Description:

let array = [[1, 1, 1], [], [4, 5, 6, 7], [0], [], [] [42]]

This line of code is missing a comma before `[42]` and was a hard to spot typo. This results in a runtime crash rather than a compile time error.

error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).
The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.

* thread #​1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
  * frame #&#8203;0: 0x0000000102a8e3ef libswiftCore.dylib`function signature specialization <Arg[0] = Exploded, Arg[1] = Exploded, Arg[2] = Dead, Arg[3] = Dead> of Swift._fatalErrorMessage(_: Swift.StaticString, _: Swift.StaticString, file: Swift.StaticString, line: Swift.UInt, flags: Swift.UInt32) -> Swift.Never + 463
    frame #&#8203;1: 0x000000010286238f libswiftCore.dylib`Swift._ArrayBuffer._checkInoutAndNativeTypeCheckedBounds(_: Swift.Int, wasNativeTypeChecked: Swift.Bool) -> () + 239
    frame #&#8203;2: 0x0000000102865221 libswiftCore.dylib`Swift.Array.subscript.getter : (Swift.Int) -> A + 81
    frame #&#8203;3: 0x0000000104eaa34e $__lldb_expr100`main at Untitled Page 2.xcplaygroundpage:7:55
    frame #&#8203;4: 0x000000010279b580 DeinitTest`linkResources + 304
    frame #&#8203;5: 0x00007fff23a5ce4c CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #&#8203;6: 0x00007fff23a5c5b8 CoreFoundation`__CFRunLoopDoBlocks + 312
    frame #&#8203;7: 0x00007fff23a57444 CoreFoundation`__CFRunLoopRun + 1284
    frame #&#8203;8: 0x00007fff23a56c16 CoreFoundation`CFRunLoopRunSpecific + 438
    frame #&#8203;9: 0x00007fff37a98bb0 GraphicsServices`GSEventRunModal + 65
    frame #&#8203;10: 0x00007fff46c97bef UIKitCore`UIApplicationMain + 1621
    frame #&#8203;11: 0x000000010279b64d DeinitTest`main + 205
    frame #&#8203;12: 0x00007fff50fb24ad libdyld.dylib`start + 1

Related discussion: https://forums.swift.org/t/is-this-a-bug-of-xcode-or-is-this-intended/26978
@theblixguy
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Reduced case:

let array = [[] [42]]

The problem is that we're parsing subscript expression inside a collection expression, so the parser doesn't throw an error for a missing comma. We can emit a warning diagnostic if we parse a subscript along with a fix-it to insert the comma.

cc @rintaro

@belkadan
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I mean, the code is valid as written. It's just doing something silly. (For a simpler example, consider [[1, 2] [3]].) But maybe the compiler should warn on it and suggest parens if you really want to subscript a literal?

@theblixguy
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Here's a fix: #26149

@theblixguy
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Fixed on master

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself
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