c++ - 函数体调用C ++末尾的奇怪循环

Question

我正在用 C++ 编写一个游戏程序，遇到了一个奇怪的问题，这似乎是这个函数独有的。

当这个函数被调用时，它会按照预期一直执行到 return 语句。但是，在执行 return 语句时，代码“跳转”到构造函数的两行，并再次执行构造函数和 return 语句之间的代码。更重要的是，当我在第二次迭代中检查传递给 FileManager 构造函数的值时，它前面附加了“level_directory”的值（但仅在构造函数内部，当我检查函数调用时一切正常）。

相关资料：

Debugger: GDB 7.6-1
OS: Arch Linux x86_64
IDE: Code::Blocks 12.11

g++ -S -masm=intel main.cpp;cat main.s | c++filt > disasm.s

In file included from game.h:9:0,
                 from main.cpp:4:
playstate.h:32:45: warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11 [enabled by default]
         const std::string level_directory = "data/levels/";

    .file   "main.cpp"
    .intel_syntax noprefix
    .text
    .globl  main
    .type   main, @function
main:
.LFB1826:
    .cfi_startproc
    .cfi_personality 0x3,__gxx_personality_v0
    .cfi_lsda 0x3,.LLSDA1826
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    push    rbx
    sub rsp, 552
    .cfi_offset 3, -24
    lea rax, [rbp-560]
    mov rdi, rax
.LEHB0:
    call    _ZN4GameC1Ev
.LEHE0:
    jmp .L2
.L3:
    lea rax, [rbp-560]
    mov rdi, rax
.LEHB1:
    call    _ZN4Game12HandleEventsEv
    lea rax, [rbp-560]
    mov rdi, rax
    call    _ZN4Game6UpdateEv
    lea rax, [rbp-560]
    mov rdi, rax
    call    _ZN4Game6RenderEv
.L2:
    lea rax, [rbp-560]
    mov rdi, rax
    call    _ZN4Game9isRunningEv
.LEHE1:
    test    al, al
    jne .L3
    lea rax, [rbp-560]
    mov rdi, rax
.LEHB2:
    call    _ZN4GameD1Ev
.LEHE2:
    mov eax, 0
    jmp .L9
.L8:
    mov rbx, rax
    lea rax, [rbp-560]
    mov rdi, rax
    call    _ZN4GameD1Ev
    mov rax, rbx
    jmp .L6
.L7:
.L6:
    mov rdi, rax
.LEHB3:
    call    _Unwind_Resume
.LEHE3:
.L9:
    add rsp, 552
    pop rbx
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1826:
    .globl  __gxx_personality_v0
    .section    .gcc_except_table,"a",@progbits
.LLSDA1826:
    .byte   0xff
    .byte   0xff
    .byte   0x1
    .uleb128 .LLSDACSE1826-.LLSDACSB1826
.LLSDACSB1826:
    .uleb128 .LEHB0-.LFB1826
    .uleb128 .LEHE0-.LEHB0
    .uleb128 .L7-.LFB1826
    .uleb128 0
    .uleb128 .LEHB1-.LFB1826
    .uleb128 .LEHE1-.LEHB1
    .uleb128 .L8-.LFB1826
    .uleb128 0
    .uleb128 .LEHB2-.LFB1826
    .uleb128 .LEHE2-.LEHB2
    .uleb128 .L7-.LFB1826
    .uleb128 0
    .uleb128 .LEHB3-.LFB1826
    .uleb128 .LEHE3-.LEHB3
    .uleb128 0
    .uleb128 0
.LLSDACSE1826:
    .text
    .size   main, .-main
    .ident  "GCC: (GNU) 4.8.0 20130502 (prerelease)"
    .section    .note.GNU-stack,"",@progbits
                                         ^

对于 playstate.cpp

    .file   "playstate.cpp"
    .intel_syntax noprefix
    .section    .text._ZN5StateC2Ev,"axG",@progbits,_ZN5StateC5Ev,comdat
    .align 2
    .weak   _ZN5StateC2Ev
    .type   _ZN5StateC2Ev, @function
_ZN5StateC2Ev:
.LFB1:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov QWORD PTR [rbp-8], rdi
    mov rax, QWORD PTR [rbp-8]
    mov QWORD PTR [rax], OFFSET FLAT:_ZTV5State+16
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1:
    .size   _ZN5StateC2Ev, .-_ZN5StateC2Ev
    .weak   _ZN5StateC1Ev
    .set    _ZN5StateC1Ev,_ZN5StateC2Ev
    .section    .text._ZN5StateD2Ev,"axG",@progbits,_ZN5StateD5Ev,comdat
    .align 2
    .weak   _ZN5StateD2Ev
    .type   _ZN5StateD2Ev, @function
_ZN5StateD2Ev:
.LFB4:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    sub rsp, 16
    mov QWORD PTR [rbp-8], rdi
    mov rax, QWORD PTR [rbp-8]
    mov QWORD PTR [rax], OFFSET FLAT:_ZTV5State+16
    mov eax, 0
    test    eax, eax
    je  .L2
    mov rax, QWORD PTR [rbp-8]
    mov rdi, rax
    call    _ZdlPv
.L2:
    leave
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE4:
    .size   _ZN5StateD2Ev, .-_ZN5StateD2Ev
    .weak   _ZN5StateD1Ev
    .set    _ZN5StateD1Ev,_ZN5StateD2Ev
    .section    .text._ZN5StateD0Ev,"axG",@progbits,_ZN5StateD0Ev,comdat
    .align 2
    .weak   _ZN5StateD0Ev
    .type   _ZN5StateD0Ev, @function
_ZN5StateD0Ev:
.LFB6:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    sub rsp, 16
    mov QWORD PTR [rbp-8], rdi
    mov rax, QWORD PTR [rbp-8]
    mov rdi, rax
    call    _ZN5StateD1Ev
    mov rax, QWORD PTR [rbp-8]
    mov rdi, rax
    call    _ZdlPv
    leave
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE6:
    .size   _ZN5StateD0Ev, .-_ZN5StateD0Ev
    .section    .rodata
.LC0:
    .string "data/levels/"
    .text
    .align 2
    .globl  _ZN9PlayStateC2Ev
    .type   _ZN9PlayStateC2Ev, @function
_ZN9PlayStateC2Ev:
.LFB1043:
    .cfi_startproc
    .cfi_personality 0x3,__gxx_personality_v0
    .cfi_lsda 0x3,.LLSDA1043
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    push    rbx
    sub rsp, 40
    .cfi_offset 3, -24
    mov QWORD PTR [rbp-40], rdi
    mov rax, QWORD PTR [rbp-40]
    mov rdi, rax
    call    _ZN5StateC2Ev
    mov rax, QWORD PTR [rbp-40]
    mov QWORD PTR [rax], OFFSET FLAT:_ZTV9PlayState+16
    lea rax, [rbp-17]
    mov rdi, rax
    call    _ZNSaIcEC1Ev
    mov rax, QWORD PTR [rbp-40]
    lea rcx, [rax+8]
    lea rax, [rbp-17]
    mov rdx, rax
    mov esi, OFFSET FLAT:.LC0
    mov rdi, rcx
.LEHB0:
    call    _ZNSsC1EPKcRKSaIcE
.LEHE0:
    lea rax, [rbp-17]
    mov rdi, rax
    call    _ZNSaIcED1Ev
    jmp .L10
.L9:
    mov rbx, rax
    lea rax, [rbp-17]
    mov rdi, rax
    call    _ZNSaIcED1Ev
    mov rax, QWORD PTR [rbp-40]
    mov rdi, rax
    call    _ZN5StateD2Ev
    mov rax, rbx
    mov rdi, rax
.LEHB1:
    call    _Unwind_Resume
.LEHE1:
.L10:
    add rsp, 40
    pop rbx
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1043:
    .globl  __gxx_personality_v0
    .section    .gcc_except_table,"a",@progbits
.LLSDA1043:
    .byte   0xff
    .byte   0xff
    .byte   0x1
    .uleb128 .LLSDACSE1043-.LLSDACSB1043
.LLSDACSB1043:
    .uleb128 .LEHB0-.LFB1043
    .uleb128 .LEHE0-.LEHB0
    .uleb128 .L9-.LFB1043
    .uleb128 0
    .uleb128 .LEHB1-.LFB1043
    .uleb128 .LEHE1-.LEHB1
    .uleb128 0
    .uleb128 0
.LLSDACSE1043:
    .text
    .size   _ZN9PlayStateC2Ev, .-_ZN9PlayStateC2Ev
    .globl  _ZN9PlayStateC1Ev
    .set    _ZN9PlayStateC1Ev,_ZN9PlayStateC2Ev
    .align 2
    .globl  _ZN9PlayStateD2Ev
    .type   _ZN9PlayStateD2Ev, @function
_ZN9PlayStateD2Ev:
.LFB1046:
    .cfi_startproc
    .cfi_personality 0x3,__gxx_personality_v0
    .cfi_lsda 0x3,.LLSDA1046
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    push    rbx
    sub rsp, 24
    .cfi_offset 3, -24
    mov QWORD PTR [rbp-24], rdi
    mov rax, QWORD PTR [rbp-24]
    mov QWORD PTR [rax], OFFSET FLAT:_ZTV9PlayState+16
    mov rax, QWORD PTR [rbp-24]
    add rax, 8
    mov rdi, rax
.LEHB2:
    call    _ZNSsD1Ev
.LEHE2:
    mov rax, QWORD PTR [rbp-24]
    mov rdi, rax
    call    _ZN5StateD2Ev
    mov eax, 0
    test    eax, eax
    je  .L16
    mov rax, QWORD PTR [rbp-24]
    mov rdi, rax
    call    _ZdlPv
    jmp .L16
.L15:
    mov rbx, rax
    mov rax, QWORD PTR [rbp-24]
    mov rdi, rax
    call    _ZN5StateD2Ev
    mov rax, rbx
    mov rdi, rax
.LEHB3:
    call    _Unwind_Resume
.LEHE3:
.L16:
    add rsp, 24
    pop rbx
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1046:
    .section    .gcc_except_table
.LLSDA1046:
    .byte   0xff
    .byte   0xff
    .byte   0x1
    .uleb128 .LLSDACSE1046-.LLSDACSB1046
.LLSDACSB1046:
    .uleb128 .LEHB2-.LFB1046
    .uleb128 .LEHE2-.LEHB2
    .uleb128 .L15-.LFB1046
    .uleb128 0
    .uleb128 .LEHB3-.LFB1046
    .uleb128 .LEHE3-.LEHB3
    .uleb128 0
    .uleb128 0
.LLSDACSE1046:
    .text
    .size   _ZN9PlayStateD2Ev, .-_ZN9PlayStateD2Ev
    .globl  _ZN9PlayStateD1Ev
    .set    _ZN9PlayStateD1Ev,_ZN9PlayStateD2Ev
    .align 2
    .globl  _ZN9PlayStateD0Ev
    .type   _ZN9PlayStateD0Ev, @function
_ZN9PlayStateD0Ev:
.LFB1048:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    sub rsp, 16
    mov QWORD PTR [rbp-8], rdi
    mov rax, QWORD PTR [rbp-8]
    mov rdi, rax
    call    _ZN9PlayStateD1Ev
    mov rax, QWORD PTR [rbp-8]
    mov rdi, rax
    call    _ZdlPv
    leave
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1048:
    .size   _ZN9PlayStateD0Ev, .-_ZN9PlayStateD0Ev
    .align 2
    .globl  _ZN9PlayState5EnterEv
    .type   _ZN9PlayState5EnterEv, @function
_ZN9PlayState5EnterEv:
.LFB1049:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov QWORD PTR [rbp-8], rdi
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1049:
    .size   _ZN9PlayState5EnterEv, .-_ZN9PlayState5EnterEv
    .align 2
    .globl  _ZN9PlayState5LeaveEv
    .type   _ZN9PlayState5LeaveEv, @function
_ZN9PlayState5LeaveEv:
.LFB1050:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov QWORD PTR [rbp-8], rdi
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1050:
    .size   _ZN9PlayState5LeaveEv, .-_ZN9PlayState5LeaveEv
    .align 2
    .globl  _ZN9PlayState6ResumeEv
    .type   _ZN9PlayState6ResumeEv, @function
_ZN9PlayState6ResumeEv:
.LFB1051:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov QWORD PTR [rbp-8], rdi
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1051:
    .size   _ZN9PlayState6ResumeEv, .-_ZN9PlayState6ResumeEv
    .align 2
    .globl  _ZN9PlayState5PauseEv
    .type   _ZN9PlayState5PauseEv, @function
_ZN9PlayState5PauseEv:
.LFB1052:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov QWORD PTR [rbp-8], rdi
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1052:
    .size   _ZN9PlayState5PauseEv, .-_ZN9PlayState5PauseEv
    .align 2
    .globl  _ZN9PlayState12HandleEventsEv
    .type   _ZN9PlayState12HandleEventsEv, @function
_ZN9PlayState12HandleEventsEv:
.LFB1053:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov QWORD PTR [rbp-8], rdi
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1053:
    .size   _ZN9PlayState12HandleEventsEv, .-_ZN9PlayState12HandleEventsEv
    .align 2
    .globl  _ZN9PlayState6UpdateEv
    .type   _ZN9PlayState6UpdateEv, @function
_ZN9PlayState6UpdateEv:
.LFB1054:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov QWORD PTR [rbp-8], rdi
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1054:
    .size   _ZN9PlayState6UpdateEv, .-_ZN9PlayState6UpdateEv
    .align 2
    .globl  _ZN9PlayState6RenderEv
    .type   _ZN9PlayState6RenderEv, @function
_ZN9PlayState6RenderEv:
.LFB1055:
    .cfi_startproc
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    mov QWORD PTR [rbp-8], rdi
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1055:
    .size   _ZN9PlayState6RenderEv, .-_ZN9PlayState6RenderEv
    .align 2
    .globl  _ZN9PlayState9LoadLevelESs
    .type   _ZN9PlayState9LoadLevelESs, @function
_ZN9PlayState9LoadLevelESs:
.LFB1056:
    .cfi_startproc
    .cfi_personality 0x3,__gxx_personality_v0
    .cfi_lsda 0x3,.LLSDA1056
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    push    rbx
    sub rsp, 600
    .cfi_offset 3, -24
    mov QWORD PTR [rbp-600], rdi
    mov QWORD PTR [rbp-608], rsi
    mov rax, QWORD PTR [rbp-600]
    lea rcx, [rax+8]
    lea rax, [rbp-48]
    mov rdx, QWORD PTR [rbp-608]
    mov rsi, rcx
    mov rdi, rax
.LEHB4:
    call    _ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_
.LEHE4:
    lea rcx, [rbp-48]
    lea rax, [rbp-592]
    mov edx, 114
    mov rsi, rcx
    mov rdi, rax
.LEHB5:
    call    _ZN11FileManagerC1ERKSsc
.LEHE5:
    lea rax, [rbp-32]
    lea rcx, [rbp-592]
    mov edx, 32
    mov rsi, rcx
    mov rdi, rax
.LEHB6:
    call    _ZN11FileManager14ReadLineStringEc
    lea rax, [rbp-32]
    mov rdi, rax
    call    _ZNSsD1Ev
.LEHE6:
    nop
    lea rax, [rbp-592]
    mov rdi, rax
.LEHB7:
    call    _ZN11FileManagerD1Ev
.LEHE7:
    lea rax, [rbp-48]
    mov rdi, rax
.LEHB8:
    call    _ZNSsD1Ev
.LEHE8:
    jmp .L34
.L33:
    mov rbx, rax
    lea rax, [rbp-592]
    mov rdi, rax
    call    _ZN11FileManagerD1Ev
    jmp .L29
.L32:
    mov rbx, rax
.L29:
    lea rax, [rbp-48]
    mov rdi, rax
    call    _ZNSsD1Ev
    mov rax, rbx
    jmp .L30
.L31:
.L30:
    mov rdi, rax
.LEHB9:
    call    _Unwind_Resume
.LEHE9:
.L34:
    add rsp, 600
    pop rbx
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1056:
    .section    .gcc_except_table
.LLSDA1056:
    .byte   0xff
    .byte   0xff
    .byte   0x1
    .uleb128 .LLSDACSE1056-.LLSDACSB1056
.LLSDACSB1056:
    .uleb128 .LEHB4-.LFB1056
    .uleb128 .LEHE4-.LEHB4
    .uleb128 .L31-.LFB1056
    .uleb128 0
    .uleb128 .LEHB5-.LFB1056
    .uleb128 .LEHE5-.LEHB5
    .uleb128 .L32-.LFB1056
    .uleb128 0
    .uleb128 .LEHB6-.LFB1056
    .uleb128 .LEHE6-.LEHB6
    .uleb128 .L33-.LFB1056
    .uleb128 0
    .uleb128 .LEHB7-.LFB1056
    .uleb128 .LEHE7-.LEHB7
    .uleb128 .L32-.LFB1056
    .uleb128 0
    .uleb128 .LEHB8-.LFB1056
    .uleb128 .LEHE8-.LEHB8
    .uleb128 .L31-.LFB1056
    .uleb128 0
    .uleb128 .LEHB9-.LFB1056
    .uleb128 .LEHE9-.LEHB9
    .uleb128 0
    .uleb128 0
.LLSDACSE1056:
    .text
    .size   _ZN9PlayState9LoadLevelESs, .-_ZN9PlayState9LoadLevelESs
    .section    .text._ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_,"axG",@progbits,_ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_,comdat
    .weak   _ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_
    .type   _ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_, @function
_ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_:
.LFB1069:
    .cfi_startproc
    .cfi_personality 0x3,__gxx_personality_v0
    .cfi_lsda 0x3,.LLSDA1069
    push    rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    mov rbp, rsp
    .cfi_def_cfa_register 6
    push    rbx
    sub rsp, 40
    .cfi_offset 3, -24
    mov QWORD PTR [rbp-24], rdi
    mov QWORD PTR [rbp-32], rsi
    mov QWORD PTR [rbp-40], rdx
    mov rdx, QWORD PTR [rbp-32]
    mov rax, QWORD PTR [rbp-24]
    mov rsi, rdx
    mov rdi, rax
.LEHB10:
    call    _ZNSsC1ERKSs
.LEHE10:
    mov rdx, QWORD PTR [rbp-40]
    mov rax, QWORD PTR [rbp-24]
    mov rsi, rdx
    mov rdi, rax
.LEHB11:
    call    _ZNSs6appendERKSs
.LEHE11:
    jmp .L39
.L38:
    mov rbx, rax
    mov rax, QWORD PTR [rbp-24]
    mov rdi, rax
    call    _ZNSsD1Ev
    mov rax, rbx
    mov rdi, rax
.LEHB12:
    call    _Unwind_Resume
.LEHE12:
.L39:
    mov rax, QWORD PTR [rbp-24]
    add rsp, 40
    pop rbx
    pop rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1069:
    .section    .gcc_except_table
.LLSDA1069:
    .byte   0xff
    .byte   0xff
    .byte   0x1
    .uleb128 .LLSDACSE1069-.LLSDACSB1069
.LLSDACSB1069:
    .uleb128 .LEHB10-.LFB1069
    .uleb128 .LEHE10-.LEHB10
    .uleb128 0
    .uleb128 0
    .uleb128 .LEHB11-.LFB1069
    .uleb128 .LEHE11-.LEHB11
    .uleb128 .L38-.LFB1069
    .uleb128 0
    .uleb128 .LEHB12-.LFB1069
    .uleb128 .LEHE12-.LEHB12
    .uleb128 0
    .uleb128 0
.LLSDACSE1069:
    .section    .text._ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_,"axG",@progbits,_ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_,comdat
    .size   _ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_, .-_ZStplIcSt11char_traitsIcESaIcEESbIT_T0_T1_ERKS6_S8_
    .weak   _ZTV9PlayState
    .section    .rodata._ZTV9PlayState,"aG",@progbits,_ZTV9PlayState,comdat
    .align 32
    .type   _ZTV9PlayState, @object
    .size   _ZTV9PlayState, 88
_ZTV9PlayState:
    .quad   0
    .quad   _ZTI9PlayState
    .quad   _ZN9PlayStateD1Ev
    .quad   _ZN9PlayStateD0Ev
    .quad   _ZN9PlayState5EnterEv
    .quad   _ZN9PlayState5LeaveEv
    .quad   _ZN9PlayState5PauseEv
    .quad   _ZN9PlayState6ResumeEv
    .quad   _ZN9PlayState12HandleEventsEv
    .quad   _ZN9PlayState6UpdateEv
    .quad   _ZN9PlayState6RenderEv
    .weak   _ZTV5State
    .section    .rodata._ZTV5State,"aG",@progbits,_ZTV5State,comdat
    .align 32
    .type   _ZTV5State, @object
    .size   _ZTV5State, 88
_ZTV5State:
    .quad   0
    .quad   _ZTI5State
    .quad   _ZN5StateD1Ev
    .quad   _ZN5StateD0Ev
    .quad   __cxa_pure_virtual
    .quad   __cxa_pure_virtual
    .quad   __cxa_pure_virtual
    .quad   __cxa_pure_virtual
    .quad   __cxa_pure_virtual
    .quad   __cxa_pure_virtual
    .quad   __cxa_pure_virtual
    .weak   _ZTI9PlayState
    .section    .rodata._ZTI9PlayState,"aG",@progbits,_ZTI9PlayState,comdat
    .align 16
    .type   _ZTI9PlayState, @object
    .size   _ZTI9PlayState, 24
_ZTI9PlayState:
    .quad   _ZTVN10__cxxabiv120__si_class_type_infoE+16
    .quad   _ZTS9PlayState
    .quad   _ZTI5State
    .weak   _ZTS9PlayState
    .section    .rodata._ZTS9PlayState,"aG",@progbits,_ZTS9PlayState,comdat
    .type   _ZTS9PlayState, @object
    .size   _ZTS9PlayState, 11
_ZTS9PlayState:
    .string "9PlayState"
    .weak   _ZTS5State
    .section    .rodata._ZTS5State,"aG",@progbits,_ZTS5State,comdat
    .type   _ZTS5State, @object
    .size   _ZTS5State, 7
_ZTS5State:
    .string "5State"
    .weak   _ZTI5State
    .section    .rodata._ZTI5State,"aG",@progbits,_ZTI5State,comdat
    .align 16
    .type   _ZTI5State, @object
    .size   _ZTI5State, 16
_ZTI5State:
    .quad   _ZTVN10__cxxabiv117__class_type_infoE+16
    .quad   _ZTS5State
    .section    .rodata
    .align 8
    .type   _ZZL18__gthread_active_pvE20__gthread_active_ptr, @object
    .size   _ZZL18__gthread_active_pvE20__gthread_active_ptr, 8
_ZZL18__gthread_active_pvE20__gthread_active_ptr:
    .quad   _ZL28__gthrw___pthread_key_createPjPFvPvE
    .weakref    _ZL28__gthrw___pthread_key_createPjPFvPvE,__pthread_key_create
    .ident  "GCC: (GNU) 4.8.0 20130502 (prerelease)"
    .section    .note.GNU-stack,"",@progbits

有问题的功能：

void
PlayState::LoadLevel(const std::string level_name)
{
    std::string full_path = level_directory + level_name;
    FileManager file(full_path, 'r');
    file.ReadLineString(' ');
    return;
}

FileManager 的构造函数：

FileManager::FileManager(const std::string &path, char access_type)
{
    buffer = "";
    file.exceptions(std::fstream::failbit | std::fstream::badbit);
    try
    {
        switch (access_type)
        {
        case 'r':
            file.open(path, std::ios_base::openmode::_S_in);
            break;
        case 'w':
            file.open(path, std::ios_base::openmode::_S_out);
            break;
        default:
            std::cout << "Access type: " << access_type << " not recognised" << std::endl;
            break;
        }
    }
    catch(std::fstream::failure)
    {
        std::cout << "I/O exception in FileManager constructor.\nPlease check that the file exists.\nPath: " << path << "\nAccess type: " << access_type << std::endl;
    }
    return;
}

FileManager::ReadLineString:

/*
Reads the next line and returns it as a string
*/
std::string
FileManager::ReadLineString()
{
    getline(file, buffer);
    return buffer;

}

/*
As above, but allows to use of a delimiter.
*/
std::string
FileManager::ReadLineString(char delimiter)
{
    getline(file, buffer, delimiter);
    return buffer;
}

Answer 1

我会通过带有一粒盐的调试器来采取任何此类行为。尝试在构造函数中添加打印语句。最有可能的是，您会发现它根本没有被调用两次。调试器很容易对它们所在的源代码行感到困惑。

如有疑问，请在调试器中使用汇编级步进（即gdb 中的si/ ni）。这将消除任何疑问，真正执行的是什么。