• d-bugmail puremagic.com (118/118) Apr 30 2018 https://issues.dlang.org/show_bug.cgi?id=18814

d-bugmail puremagic.com writes:

https://issues.dlang.org/show_bug.cgi?id=18814

          Issue ID: 18814
           Summary: Segmentation Fault in GC From writeln Call
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: druntime
          Assignee: nobody puremagic.com
          Reporter: jack jackstouffer.com

Code reduced via dustmite

main.d
=========
import std.traits;
import std.stdio;

/**
 * Custom `string` type optimized for both small sizes and for appending
 * large amounts of data.
 */
struct String
{
    /// ditto
    ref opOpAssign(string op, R)(R r)
    {
        convertToBig();
        large.ptr[large.len .. r.length] = r;
    }

    ubyte isBig()
    {
        return small.slen;
    }

    void convertToBig()
    {
        import core.memory;
        char* p = cast(char*) GC.malloc(GC.BlkAttr.NO_SCAN);

        large.ptr = p;
    }

    struct Small
    {
        ubyte slen;
    }

    struct Large
    {
        size_t len;
        char* ptr;
    }

    Small small;
    Large large;
}

unittest
{
    auto a = String();
    a ~= " test test test test test";
    writeln(a);
}
=========

$ dmd -unittest -main -run main.d
String(Small(0), Large(0, 10AB9E000))
0   dmd_runO05sQ2                       0x000000010aacf6c8
_D4core7runtime18runModuleUnitTestsUZ19unittestSegvHandlerUNbNiiPSQCm3sys5posix6signal9siginfo_tPvZv
+ 56
1   libsystem_platform.dylib            0x00007fff512c1f5a _sigtramp + 26
2   ???                                 0x000000011a8e9088 0x0 + 4740518024
3   dmd_runO05sQ2                       0x000000010aadc8a7
_D2gc4impl12conservativeQw14ConservativeGC__T9runLockedS_DQCeQCeQCcQCnQBs12mallocNoSyncMFNbmkKmxC8TypeInfoZPvS_DQEgQEgQEeQEp10mallocTimelS_DQFiQFiQFgQFr10numMallocslTmTkTmTxQCzZQFcMFNbKmKkKmKxQDsZQDl
+ 147
4   dmd_runO05sQ2                       0x000000010aad66c3
_D2gc4impl12conservativeQw14ConservativeGC6qallocMFNbmkxC8TypeInfoZS4core6memory8BlkInfo_
+ 115
5   dmd_runO05sQ2                       0x000000010aad58eb gc_qalloc + 51
6   dmd_runO05sQ2                       0x000000010aacefec
_D4core6memory2GC6qallocFNaNbmkxC8TypeInfoZSQBqQBo8BlkInfo_ + 32
7   dmd_runO05sQ2                       0x000000010aac07fa
_D3std5array__T8AppenderTAaZQn13ensureAddableMFNaNbNemZv + 286
8   dmd_runO05sQ2                       0x000000010aac0c7b
_D3std5array__T8AppenderTAaZQn__T3putTAxaZQjMFQiZ10bigDataFunMFNaNbNemZQBu + 31
9   dmd_runO05sQ2                       0x000000010aac0bcd
_D3std5array__T8AppenderTAaZQn__T3putTAxaZQjMFNaNbNfQoZv + 33
10  dmd_runO05sQ2                       0x000000010aac0ba8
_D3std5range10primitives__T5doPutTSQBh5array__T8AppenderTAaZQnTAxaZQBoFNaNbNfKQBsKQtZv
+ 28
11  dmd_runO05sQ2                       0x000000010aac0b88
_D3std5range10primitives__T3putTSQBf5array__T8AppenderTAaZQnTAxaZQBmFNaNbNfKQBsQsZv
+ 28
12  dmd_runO05sQ2                       0x000000010aac0a34
_D3std6format__T10FormatSpecTaZQp__T17writeUpToNextSpecTSQCd5array__T8AppenderTAaZQnZQBxMFNaNfKQBnZb
+ 184
13  dmd_runO05sQ2                       0x000000010aab7c5b
_D3std6format__T10FormatSpecTaZQp20__unittest_L1204_C11FNaNfZv + 95
14  dmd_runO05sQ2                       0x000000010aab7446 _D4main9__modtestFZv
+ 14
15  dmd_runO05sQ2                       0x000000010aacf720
_D4core7runtime18runModuleUnitTestsUZ14__foreachbody2MFPS6object10ModuleInfoZi
+ 56
16  dmd_runO05sQ2                       0x000000010aac4953
_D6object10ModuleInfo7opApplyFMDFPSQBhQBdZiZ9__lambda2MFyPSQCfQCbZi + 35
17  dmd_runO05sQ2                       0x000000010aae8ee6
_D2rt5minfo17moduleinfos_applyFMDFyPS6object10ModuleInfoZiZ14__foreachbody2MFKSQCz19sections_osx_x86_6412SectionGroupZi
+ 86
18  dmd_runO05sQ2                       0x000000010aae8e71
_D2rt5minfo17moduleinfos_applyFMDFyPS6object10ModuleInfoZiZi + 33
19  dmd_runO05sQ2                       0x000000010aac492a
_D6object10ModuleInfo7opApplyFMDFPSQBhQBdZiZi + 34
20  dmd_runO05sQ2                       0x000000010aacf4d7 runModuleUnitTests +
335
21  dmd_runO05sQ2                       0x000000010aae12c1
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZv + 37
22  dmd_runO05sQ2                       0x000000010aae124c
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ7tryExecMFMDFZvZv + 32
23  dmd_runO05sQ2                       0x000000010aae11ba _d_run_main + 486
24  dmd_runO05sQ2                       0x000000010aab7468 main + 16
25  libdyld.dylib                       0x00007fff50fb3015 start + 1
26  ???                                 0x0000000000000001 0x0 + 1
Error: program killed by signal 11

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