[LLVMbugs] [Bug 22256] New: Constructor with empty initializer list generates code that crashes at runtime

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Sat Jan 17 18:20:53 PST 2015


            Bug ID: 22256
           Summary: Constructor with empty initializer list generates code
                    that crashes at runtime
           Product: clang
           Version: 3.5
          Hardware: PC
                OS: MacOS X
            Status: NEW
          Severity: normal
          Priority: P
         Component: C++
          Assignee: unassignedclangbugs at nondot.org
          Reporter: evan.exe at gmail.com
                CC: dgregor at apple.com, llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Created attachment 13699
  --> http://llvm.org/bugs/attachment.cgi?id=13699&action=edit

The attached code contains a List<T> wrapper for std::vector<T> and two
constructors, one default constructor and one that takes a

Steps (using latest OS X Command Line Tools, version 6.1):
1. Compile attached file using "clang++ -std=c++11 main.cpp"
2. Run the attached file using "MallocScribble=1 ./a.out"

I expect that "auto keys = new List<std::string>({});" and "auto keys = new
List<std::string>();" both create an empty list and both do not crash. Each one
can be tested by commenting that one in and commenting the other one out.

The code for the default constructor runs fine but the code for the initializer
list constructor crashes at runtime. It appears the compiler is generating
incorrect code for the initializer list constructor. Poking around the Xcode
debugger reveals that the __begin_ std::vector member is 0 but the __end_
std::vector member is 24, which is sizeof(std::string). The size() method
returns 1 but get(0) crashes.

This code is a reduced test case from a real app. The real app crashes without
any debug options but the reduced code needs MallocScribble=1 to trigger the

Also logged as rdar://19510408

clang++ --version:
Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix

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