Bug 23106 – the simple main() leaks 72 bytes

``` module a; int main() { return 0; } ``` valgrind ./a ``` ==1210593== For lists of detected and suppressed errors, rerun with: -s ==1210593== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) [basile@pc temp]$ valgrind --leak-check=full --show-leak-kinds=all ./a ==1210595== Memcheck, a memory error detector ==1210595== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==1210595== Using Valgrind-3.16.1 and LibVEX; rerun with -h for copyright info ==1210595== Command: ./a ==1210595== ==1210595== ==1210595== HEAP SUMMARY: ==1210595== in use at exit: 96 bytes in 2 blocks ==1210595== total heap usage: 151 allocs, 149 frees, 15,080 bytes allocated ==1210595== ==1210595== 24 bytes in 1 blocks are still reachable in loss record 1 of 2 ==1210595== at 0x4839747: malloc (vg_replace_malloc.c:306) ==1210595== by 0x483BD32: realloc (vg_replace_malloc.c:834) ==1210595== by 0x437361: _D4core8internal9container6common8xreallocFNbNiPvmZQe (in /home/basile/Bureau/temp/a) ==1210595== by 0x445872: _D4core8internal2gc4impl5protoQo7ProtoGC8addRangeMFNbNiPvmxC8TypeInfoZv (in /home/basile/Bureau/temp/a) ==1210595== by 0x43763B: gc_addRange (in /home/basile/Bureau/temp/a) ==1210595== by 0x439441: _D2rt6memory16initStaticDataGCFZ14__foreachbody1MFNbNiKSQCc19sections_elf_shared3DSOZi (in /home/basile/Bureau/temp/a) ==1210595== by 0x43B93F: _D2rt19sections_elf_shared3DSO7opApplyFMDFKSQBqQBqQyZiZi (in /home/basile/Bureau/temp/a) ==1210595== by 0x4393E4: _D2rt6memory16initStaticDataGCFZv (in /home/basile/Bureau/temp/a) ==1210595== by 0x437EC4: rt_init (in /home/basile/Bureau/temp/a) ==1210595== by 0x434B67: _D2rt6dmain212_d_run_main2UAAamPUQgZiZ6runAllMFZv (in /home/basile/Bureau/temp/a) ==1210595== by 0x434B04: _D2rt6dmain212_d_run_main2UAAamPUQgZiZ7tryExecMFMDFZvZv (in /home/basile/Bureau/temp/a) ==1210595== by 0x434A65: _d_run_main2 (in /home/basile/Bureau/temp/a) ==1210595== ==1210595== 72 bytes in 1 blocks are still reachable in loss record 2 of 2 ==1210595== at 0x483BCE8: realloc (vg_replace_malloc.c:834) ==1210595== by 0x465FB5: _d_register_manual_gc (in /home/basile/Bureau/temp/a) ==1210595== by 0x46E69C: __libc_csu_init (in /home/basile/Bureau/temp/a) ==1210595== by 0x4A2D16D: (below main) (in /usr/lib64/libc-2.32.so) ==1210595== ==1210595== LEAK SUMMARY: ==1210595== definitely lost: 0 bytes in 0 blocks ==1210595== indirectly lost: 0 bytes in 0 blocks ==1210595== possibly lost: 0 bytes in 0 blocks ==1210595== still reachable: 96 bytes in 2 blocks ==1210595== suppressed: 0 bytes in 0 blocks ==1210595== ==1210595== For lists of detected and suppressed errors, rerun with: -s ==1210595== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) ``` seems to be caused by the gc initialization

==117347== Memcheck, a memory error detector ==117347== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al. ==117347== Using Valgrind-3.21.0 and LibVEX; rerun with -h for copyright info ==117347== Command: /tmp/temp_7F336C18C4D0 ==117347== ==117347== realloc() with size 0 ==117347== at 0x4848A40: realloc (vg_replace_malloc.c:1649) ==117347== by 0x4389F1: rt.minfo.ModuleGroup.sortCtors(immutable(char)[]) (in /tmp/temp_7F336C18C4D0) ==117347== by 0x439608: rt.minfo.ModuleGroup.sortCtors() (in /tmp/temp_7F336C18C4D0) ==117347== by 0x4398DC: rt.minfo.rt_moduleCtor().__foreachbody1(ref rt.sections_elf_shared.DSO) (in /tmp/temp_7F336C18C4D0) ==117347== by 0x439D31: rt.sections_elf_shared.DSO.opApply(scope int(ref rt.sections_elf_shared.DSO) delegate) (in /tmp/temp_7F336C18C4D0) ==117347== by 0x4398BC: rt_moduleCtor (in /tmp/temp_7F336C18C4D0) ==117347== by 0x436F39: rt_init (in /tmp/temp_7F336C18C4D0) ==117347== by 0x433BD7: rt.dmain2._d_run_main2(char[][], ulong, extern(C) int(char[][]) function).runAll() (in /tmp/temp_7F336C18C4D0) ==117347== by 0x433B75: rt.dmain2._d_run_main2(char[][], ulong, extern(C) int(char[][]) function).tryExec(scope void() delegate) (in /tmp/temp_7F336C18C4D0) ==117347== by 0x433ADE: _d_run_main2 (in /tmp/temp_7F336C18C4D0) ==117347== by 0x4338C7: _d_run_main (in /tmp/temp_7F336C18C4D0) ==117347== by 0x4337E1: main (entrypoint.d:29) ==117347== Address 0x4b50c00 is 0 bytes inside a block of size 104 alloc'd ==117347== at 0x484382F: malloc (vg_replace_malloc.c:431) ==117347== by 0x438947: rt.minfo.ModuleGroup.sortCtors(immutable(char)[]) (in /tmp/temp_7F336C18C4D0) ==117347== by 0x439608: rt.minfo.ModuleGroup.sortCtors() (in /tmp/temp_7F336C18C4D0) ==117347== by 0x4398DC: rt.minfo.rt_moduleCtor().__foreachbody1(ref rt.sections_elf_shared.DSO) (in /tmp/temp_7F336C18C4D0) ==117347== by 0x439D31: rt.sections_elf_shared.DSO.opApply(scope int(ref rt.sections_elf_shared.DSO) delegate) (in /tmp/temp_7F336C18C4D0) ==117347== by 0x4398BC: rt_moduleCtor (in /tmp/temp_7F336C18C4D0) ==117347== by 0x436F39: rt_init (in /tmp/temp_7F336C18C4D0) ==117347== by 0x433BD7: rt.dmain2._d_run_main2(char[][], ulong, extern(C) int(char[][]) function).runAll() (in /tmp/temp_7F336C18C4D0) ==117347== by 0x433B75: rt.dmain2._d_run_main2(char[][], ulong, extern(C) int(char[][]) function).tryExec(scope void() delegate) (in /tmp/temp_7F336C18C4D0) ==117347== by 0x433ADE: _d_run_main2 (in /tmp/temp_7F336C18C4D0) ==117347== by 0x4338C7: _d_run_main (in /tmp/temp_7F336C18C4D0) ==117347== by 0x4337E1: main (entrypoint.d:29) ==117347== ==117347== ==117347== HEAP SUMMARY: ==117347== in use at exit: 72 bytes in 2 blocks ==117347== total heap usage: 101 allocs, 99 frees, 9,040 bytes allocated ==117347== ==117347== LEAK SUMMARY: ==117347== definitely lost: 0 bytes in 0 blocks ==117347== indirectly lost: 0 bytes in 0 blocks ==117347== possibly lost: 0 bytes in 0 blocks ==117347== still reachable: 72 bytes in 2 blocks ==117347== suppressed: 0 bytes in 0 blocks ==117347== Rerun with --leak-check=full to see details of leaked memory ==117347== ==117347== For lists of detected and suppressed errors, rerun with: -s ==117347== ERROR SUMMARY: 16 errors from 1 contexts (suppressed: 0 from 0) [basile@pc styx]$

Since we now have proper valgrind support including a test in the test suite (https://github.com/dlang/dmd/pull/15304), can you still reproduce this?

I'm not the author of this issue, but I can still replicate it. Same thing 72 bytes. Compiling with both dmd and dub produces this leak and turning on -betterC switch fixes issue. Also, just a note, changing compiler to LDC makes it even worse (going to report on their repo).

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