书上和网上在很多地方都对const 的重载做了一些解释，但感觉都不是很详细。还有很多同学在不同的地方发问关于const 重载的问题，这里我又重新看了一下，做了一个简单的分析也可能有不对的地方，欢迎讨论。
所谓重载，是指允许存在多个同名函数，而这些函数的参数表不同，即函数名相同但函数的签名不同。重载并不是面向对象编程的特有属性，这是因为重载是在编译阶段实现的，编译器根据函数不同的参数表，对同名函数的名称做修饰，然后这些同名函数就成了不同的函数（这一点稍后有例子）。了
Const 参数重载解析：
关于const 重载几乎在所有c++的书中者提到过但大部分只是一句话，例如在《C++ primer》一书中这样描述：“可基于函数的引用形参是指向 const 对象还是指向非 const 对象，实现函数重载。将引用形参定义为 const 来重载函数是合法的，因为编译器可以根据实参是否为 const 确定调用哪一个函数。”
但是这一段描述并没有给出引用、指针和值传递前加const的实质区别是什么。在用非const的指针，引用和值均可转化为const的。这一点没有太多可说明的东东。
对于函数值传递的情况，因为参数传递是通过复制实参创建一个临时变量传递进函数的，函数内只能改变临时变量，但无法改变实参。则这个时候无论加不加const对实参不会产生任何影响。但是在引用或指针传递函数调用中，因为传进去的是一个引用或指针，这样函数内部可以改变引用或指针所指向的变量，这时const 才是实实在在地保护了实参所指向的变量。因为在编译阶段编译器对调用函数的选择是根据实参进行的，所以，只有引用传递和指针传递可以用是否加const来重载。
下面给出一个例子可能就更明白了：
C++ 代码
1 #include<iostream> 2 3 class A{ 4 public: 5 A(); 6 int foo(int *test); 7 int foo(const int *test); 8 }; 9 A::A(){10 }11 int A::foo(int *test){12 std::cout << *test << " A::foo(int *test)" <<std::endl;13 return 1;14 }15 int A::foo(const int *test){16 std::cout << *test << " A::foo(const int *test)" <<std::endl;17 return 1;18 }19 int main()20 {21 const int b =5;22 int c = 3;23 A a;24 a.foo(&b);25 a.foo(&c);26 return 1;27 }28
输出：
5 A::foo(const int *test)3 A::foo(int *test)
那么编译器又是怎样工作的，通过g++ -S选项将汇编代码生成出来，通过AT&T汇编代码可以看出一些端倪来（之所以用AT&T汇编是因为VS生成的中间代码实在是让人头晕）：
代码
1 .file "overload.cpp" 2 .section .ctors,"aw",@progbits 3 .align 4 4 .long _GLOBAL__I__ZN1AC2Ev 5 .text 6 .align 2 7 .globl _ZN1AC2Ev 8 .type _ZN1AC2Ev, @function 9 _ZN1AC2Ev: 10 .LFB1399: 11 pushl %ebp 12 .LCFI0: 13 movl %esp, %ebp 14 .LCFI1: 15 popl %ebp 16 ret 17 .LFE1399: 18 .size _ZN1AC2Ev, .-_ZN1AC2Ev 19 .globl __gxx_personality_v0 20 .align 2 21 .globl _ZN1AC1Ev 22 .type _ZN1AC1Ev, @function 23 _ZN1AC1Ev: 24 .LFB1400: 25 pushl %ebp 26 .LCFI2: 27 movl %esp, %ebp 28 .LCFI3: 29 popl %ebp 30 ret 31 .LFE1400: 32 .size _ZN1AC1Ev, .-_ZN1AC1Ev 33 .align 2 34 .type _Z41__static_initialization_and_destruction_0ii, @function 35 _Z41__static_initialization_and_destruction_0ii: 36 .LFB1411: 37 pushl %ebp 38 .LCFI4: 39 movl %esp, %ebp 40 .LCFI5: 41 subl $24, %esp 42 .LCFI6: 43 movl %eax, -4(%ebp) 44 movl %edx, -8(%ebp) 45 cmpl $1, -4(%ebp) 46 jne .L9 47 cmpl $65535, -8(%ebp) 48 jne .L9 49 movl $_ZSt8__ioinit, (%esp) 50 call _ZNSt8ios_base4InitC1Ev 51 movl $__dso_handle, 8(%esp) 52 movl $0, 4(%esp) 53 movl $__tcf_0, (%esp) 54 call __cxa_atexit 55 .L9: 56 leave 57 ret 58 .LFE1411: 59 .size _Z41__static_initialization_and_destruction_0ii, .-_Z41__static_initialization_and_destruction_0ii 60 .align 2 61 .type _GLOBAL__I__ZN1AC2Ev, @function 62 _GLOBAL__I__ZN1AC2Ev: 63 .LFB1413: 64 pushl %ebp 65 .LCFI7: 66 movl %esp, %ebp 67 .LCFI8: 68 subl $8, %esp 69 .LCFI9: 70 movl $65535, %edx 71 movl $1, %eax 72 call _Z41__static_initialization_and_destruction_0ii 73 leave 74 ret 75 .LFE1413: 76 .size _GLOBAL__I__ZN1AC2Ev, .-_GLOBAL__I__ZN1AC2Ev 77 .align 2 78 .type __tcf_0, @function 79 __tcf_0: 80 .LFB1412: 81 pushl %ebp 82 .LCFI10: 83 movl %esp, %ebp 84 .LCFI11: 85 subl $8, %esp 86 .LCFI12: 87 movl $_ZSt8__ioinit, (%esp) 88 call _ZNSt8ios_base4InitD1Ev 89 leave 90 ret 91 .LFE1412: 92 .size __tcf_0, .-__tcf_0 93 .section .rodata 94 .LC0: 95 .string " A::foo(const int *test)" 96 .text 97 .align 2 98 .globl _ZN1A3fooEPKi 99 .type _ZN1A3fooEPKi, @function100 _ZN1A3fooEPKi:101 .LFB1402:102 pushl %ebp103 .LCFI13:104 movl %esp, %ebp105 .LCFI14:106 subl $8, %esp107 .LCFI15:108 movl 12(%ebp), %eax109 movl (%eax), %eax110 movl %eax, 4(%esp)111 movl $_ZSt4cout, (%esp)112 call _ZNSolsEi113 movl $.LC0, 4(%esp)114 movl %eax, (%esp)115 call _ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc116 movl $_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_, 4(%esp)117 movl %eax, (%esp)118 call _ZNSolsEPFRSoS_E119 movl $1, %eax120 leave121 ret122 .LFE1402:123 .size _ZN1A3fooEPKi, .-_ZN1A3fooEPKi124 .section .rodata125 .LC1:126 .string " A::foo(int *test)"127 .text128 .align 2129 .globl _ZN1A3fooEPi130 .type _ZN1A3fooEPi, @function131 _ZN1A3fooEPi:132 .LFB1401:133 pushl %ebp134 .LCFI16:135 movl %esp, %ebp136 .LCFI17:137 subl $8, %esp138 .LCFI18:139 movl 12(%ebp), %eax140 movl (%eax), %eax141 movl %eax, 4(%esp)142 movl $_ZSt4cout, (%esp)143 call _ZNSolsEi144 movl $.LC1, 4(%esp)145 movl %eax, (%esp)146 call _ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc147 movl $_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_, 4(%esp)148 movl %eax, (%esp)149 call _ZNSolsEPFRSoS_E150 movl $1, %eax151 leave152 ret153 .LFE1401:154 .size _ZN1A3fooEPi, .-_ZN1A3fooEPi155 .align 2156 .globl main157 .type main, @function158 main:159 .LFB1403:160 leal 4(%esp), %ecx161 .LCFI19:162 andl $-16, %esp163 pushl -4(%ecx)164 .LCFI20:165 pushl %ebp166 .LCFI21:167 movl %esp, %ebp168 .LCFI22:169 pushl %ecx170 .LCFI23:171 subl $36, %esp172 .LCFI24:173 movl $5, -8(%ebp)174 movl $3, -12(%ebp)175 leal -13(%ebp), %eax176 movl %eax, (%esp)177 call _ZN1AC1Ev178 leal -8(%ebp), %eax179 movl %eax, 4(%esp)180 leal -13(%ebp), %eax181 movl %eax, (%esp)182 call _ZN1A3fooEPKi183 leal -12(%ebp), %eax184 movl %eax, 4(%esp)185 leal -13(%ebp), %eax186 movl %eax, (%esp)187 call _ZN1A3fooEPi188 movl $1, %eax189 addl $36, %esp190 popl %ecx191 popl %ebp192 leal -4(%ecx), %esp193 ret194 .LFE1403:195 .size main, .-main196 .local _ZSt8__ioinit197 .comm _ZSt8__ioinit,1,1198 .weakref _Z20__gthrw_pthread_oncePiPFvvE,pthread_once199 .weakref _Z27__gthrw_pthread_getspecificj,pthread_getspecific200 .weakref _Z27__gthrw_pthread_setspecificjPKv,pthread_setspecific201 .weakref _Z22__gthrw_pthread_createPmPK14pthread_attr_tPFPvS3_ES3_,pthread_create202 .weakref _Z22__gthrw_pthread_cancelm,pthread_cancel203 .weakref _Z26__gthrw_pthread_mutex_lockP15pthread_mutex_t,pthread_mutex_lock204 .weakref _Z29__gthrw_pthread_mutex_trylockP15pthread_mutex_t,pthread_mutex_trylock205 .weakref _Z28__gthrw_pthread_mutex_unlockP15pthread_mutex_t,pthread_mutex_unlock206 .weakref _Z26__gthrw_pthread_mutex_initP15pthread_mutex_tPK19pthread_mutexattr_t,pthread_mutex_init207 .weakref _Z26__gthrw_pthread_key_createPjPFvPvE,pthread_key_create208 .weakref _Z26__gthrw_pthread_key_deletej,pthread_key_delete209 .weakref _Z30__gthrw_pthread_mutexattr_initP19pthread_mutexattr_t,pthread_mutexattr_init210 .weakref _Z33__gthrw_pthread_mutexattr_settypeP19pthread_mutexattr_ti,pthread_mutexattr_settype211 .weakref _Z33__gthrw_pthread_mutexattr_destroyP19pthread_mutexattr_t,pthread_mutexattr_destroy212 .section .eh_frame,"a",@progbits213 .Lframe1:214 .long .LECIE1-.LSCIE1215 .LSCIE1:216 .long 0x0217 .byte 0x1218 .string "zP"219 .uleb128 0x1220 .sleb128 -4221 .byte 0x8222 .uleb128 0x5223 .byte 0x0224 .long __gxx_personality_v0225 .byte 0xc226 .uleb128 0x4227 .uleb128 0x4228 .byte 0x88229 .uleb128 0x1230 .align 4231 .LECIE1:232 .LSFDE5:233 .long .LEFDE5-.LASFDE5234 .LASFDE5:235 .long .LASFDE5-.Lframe1236 .long .LFB1411237 .long .LFE1411-.LFB1411238 .uleb128 0x0239 .byte 0x4240 .long .LCFI4-.LFB1411241 .byte 0xe242 .uleb128 0x8243 .byte 0x85244 .uleb128 0x2245 .byte 0x4246 .long .LCFI5-.LCFI4247 .byte 0xd248 .uleb128 0x5249 .align 4250 .LEFDE5:251 .LSFDE7:252 .long .LEFDE7-.LASFDE7253 .LASFDE7:254 .long .LASFDE7-.Lframe1255 .long .LFB1413256 .long .LFE1413-.LFB1413257 .uleb128 0x0258 .byte 0x4259 .long .LCFI7-.LFB1413260 .byte 0xe261 .uleb128 0x8262 .byte 0x85263 .uleb128 0x2264 .byte 0x4265 .long .LCFI8-.LCFI7266 .byte 0xd267 .uleb128 0x5268 .align 4269 .LEFDE7:270 .LSFDE9:271 .long .LEFDE9-.LASFDE9272 .LASFDE9:273 .long .LASFDE9-.Lframe1274 .long .LFB1412275 .long .LFE1412-.LFB1412276 .uleb128 0x0277 .byte 0x4278 .long .LCFI10-.LFB1412279 .byte 0xe280 .uleb128 0x8281 .byte 0x85282 .uleb128 0x2283 .byte 0x4284 .long .LCFI11-.LCFI10285 .byte 0xd286 .uleb128 0x5287 .align 4288 .LEFDE9:289 .LSFDE11:290 .long .LEFDE11-.LASFDE11291 .LASFDE11:292 .long .LASFDE11-.Lframe1293 .long .LFB1402294 .long .LFE1402-.LFB1402295 .uleb128 0x0296 .byte 0x4297 .long .LCFI13-.LFB1402298 .byte 0xe299 .uleb128 0x8300 .byte 0x85301 .uleb128 0x2302 .byte 0x4303 .long .LCFI14-.LCFI13304 .byte 0xd305 .uleb128 0x5306 .align 4307 .LEFDE11:308 .LSFDE13:309 .long .LEFDE13-.LASFDE13310 .LASFDE13:311 .long .LASFDE13-.Lframe1312 .long .LFB1401313 .long .LFE1401-.LFB1401314 .uleb128 0x0315 .byte 0x4316 .long .LCFI16-.LFB1401317 .byte 0xe318 .uleb128 0x8319 .byte 0x85320 .uleb128 0x2321 .byte 0x4322 .long .LCFI17-.LCFI16323 .byte 0xd324 .uleb128 0x5325 .align 4326 .LEFDE13:327 .LSFDE15:328 .long .LEFDE15-.LASFDE15329 .LASFDE15:330 .long .LASFDE15-.Lframe1331 .long .LFB1403332 .long .LFE1403-.LFB1403333 .uleb128 0x0334 .byte 0x4335 .long .LCFI19-.LFB1403336 .byte 0xc337 .uleb128 0x1338 .uleb128 0x0339 .byte 0x9340 .uleb128 0x4341 .uleb128 0x1342 .byte 0x4343 .long .LCFI20-.LCFI19344 .byte 0xc345 .uleb128 0x4346 .uleb128 0x4347 .byte 0x4348 .long .LCFI21-.LCFI20349 .byte 0xe350 .uleb128 0x8351 .byte 0x85352 .uleb128 0x2353 .byte 0x4354 .long .LCFI22-.LCFI21355 .byte 0xd356 .uleb128 0x5357 .byte 0x4358 .long .LCFI23-.LCFI22359 .byte 0x84360 .uleb128 0x3361 .align 4362 .LEFDE15:363 .ident "GCC: (GNU) 4.1.2 20070925 (Red Hat 4.1.2-33)"364 .section .note.GNU-stack,"",@progbits
如上面的代码函数：
int foo(int test);和int foo(const int test);分别被编译器生成名为：_ZN1A3fooEPKi和_ZN1A3fooEPi（这两个名字会因为编译器的不同而不同，名字只是一个区分的符号而已不用深究，只用知道重载的函数经过编译器的处理函数名字已经发生了变化。所以对于后面的汇编和链接工作就不存在重载的问题了。）这里也同时说明对重载来说在编译阶段已经完成。
对于a.foo(&b);因为变量b有const修饰所以就调用了int foo(const int test);对于a.foo(&c);调用int foo(int test);因为这个是精确匹配的。但是如果没有定义int foo(const int test);则在代码24行会出现编译错误。反过来如果没有定义函数：int foo(int test)；如下：
代码
1 #include<iostream> 2 3 class A{ 4 public: 5 A(); 6 // int foo(int *test); 7 int foo(const int *test); 8 }; 9 A::A(){10 }11 /*int A::foo(int *test){12 std::cout << *test << " A::foo(int *test)" <<std::endl;13 return 1;14 }15 */16 int A::foo(const int *test){17 std::cout << *test << " A::foo(const int *test)" <<std::endl;18 return 1;19 }20 int main()21 {22 const int b =5;23 int c = 3;24 A a;25 a.foo(&b);26 a.foo(&c);27 return 1;28 }
则输出结果为：
1 5 A::foo(const int *test)2 3 A::foo(const int *test)
原因c++ primer上讲的很清楚：“We can use a nonconstobject to initializer either aconstor nonconstreference. However, initializing aconstreference to a nonconstobject requires a conversion, whereas initializing a nonconstparameter is an exact match.”
const 成员函数重载的解析：
const 成员函数重载的解析和const参数重载解析的原理可以说是一样的。之所以这样说是因为const成员函数的解析可被看做是对函数this参数用const来修饰的过程。例如下面代码：
代码
1 #include<iostream> 2 3 class A{ 4 public: 5 A(); 6 int foo(int *test); //可看做：int foo(A *this,int *test); 7 int foo(int *test) const;//可看做：int foo(const A *this,int *test); 8 }; 9 A::A(){10 }11 int A::foo(int *test){12 std::cout << *test << "foo" <<std::endl;13 return 1;14 }15 int A::foo(int *test) const {16 std::cout << *test << "foo const" <<std::endl;17 return 1;18 }19 int main()20 {21 int b = 5;22 const A a;23 a.foo(&b);24 return 1;25 }26
生成汇编为：
代码
1 .file "overload1.cpp" 2 .section .ctors,"aw",@progbits 3 .align 4 4 .long _GLOBAL__I__ZN1AC2Ev 5 .text 6 .align 2 7 .globl _ZN1AC2Ev 8 .type _ZN1AC2Ev, @function 9 _ZN1AC2Ev: 10 .LFB1399: 11 pushl %ebp 12 .LCFI0: 13 movl %esp, %ebp 14 .LCFI1: 15 popl %ebp 16 ret 17 .LFE1399: 18 .size _ZN1AC2Ev, .-_ZN1AC2Ev 19 .globl __gxx_personality_v0 20 .align 2 21 .globl _ZN1AC1Ev 22 .type _ZN1AC1Ev, @function 23 _ZN1AC1Ev: 24 .LFB1400: 25 pushl %ebp 26 .LCFI2: 27 movl %esp, %ebp 28 .LCFI3: 29 popl %ebp 30 ret 31 .LFE1400: 32 .size _ZN1AC1Ev, .-_ZN1AC1Ev 33 .align 2 34 .type _Z41__static_initialization_and_destruction_0ii, @function 35 _Z41__static_initialization_and_destruction_0ii: 36 .LFB1411: 37 pushl %ebp 38 .LCFI4: 39 movl %esp, %ebp 40 .LCFI5: 41 subl $24, %esp 42 .LCFI6: 43 movl %eax, -4(%ebp) 44 movl %edx, -8(%ebp) 45 cmpl $1, -4(%ebp) 46 jne .L9 47 cmpl $65535, -8(%ebp) 48 jne .L9 49 movl $_ZSt8__ioinit, (%esp) 50 call _ZNSt8ios_base4InitC1Ev 51 movl $__dso_handle, 8(%esp) 52 movl $0, 4(%esp) 53 movl $__tcf_0, (%esp) 54 call __cxa_atexit 55 .L9: 56 leave 57 ret 58 .LFE1411: 59 .size _Z41__static_initialization_and_destruction_0ii, .-_Z41__static_initialization_and_destruction_0ii 60 .align 2 61 .type _GLOBAL__I__ZN1AC2Ev, @function 62 _GLOBAL__I__ZN1AC2Ev: 63 .LFB1413: 64 pushl %ebp 65 .LCFI7: 66 movl %esp, %ebp 67 .LCFI8: 68 subl $8, %esp 69 .LCFI9: 70 movl $65535, %edx 71 movl $1, %eax 72 call _Z41__static_initialization_and_destruction_0ii 73 leave 74 ret 75 .LFE1413: 76 .size _GLOBAL__I__ZN1AC2Ev, .-_GLOBAL__I__ZN1AC2Ev 77 .align 2 78 .type __tcf_0, @function 79 __tcf_0: 80 .LFB1412: 81 pushl %ebp 82 .LCFI10: 83 movl %esp, %ebp 84 .LCFI11: 85 subl $8, %esp 86 .LCFI12: 87 movl $_ZSt8__ioinit, (%esp) 88 call _ZNSt8ios_base4InitD1Ev 89 leave 90 ret 91 .LFE1412: 92 .size __tcf_0, .-__tcf_0 93 .section .rodata 94 .LC0: 95 .string "foo const" 96 .text 97 .align 2 98 .globl _ZNK1A3fooEPi 99 .type _ZNK1A3fooEPi, @function100 _ZNK1A3fooEPi:101 .LFB1402:102 pushl %ebp103 .LCFI13:104 movl %esp, %ebp105 .LCFI14:106 subl $8, %esp107 .LCFI15:108 movl 12(%ebp), %eax109 movl (%eax), %eax110 movl %eax, 4(%esp)111 movl $_ZSt4cout, (%esp)112 call _ZNSolsEi113 movl $.LC0, 4(%esp)114 movl %eax, (%esp)115 call _ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc116 movl $_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_, 4(%esp)117 movl %eax, (%esp)118 call _ZNSolsEPFRSoS_E119 movl $1, %eax120 leave121 ret122 .LFE1402:123 .size _ZNK1A3fooEPi, .-_ZNK1A3fooEPi124 .align 2125 .globl main126 .type main, @function127 main:128 .LFB1403:129 leal 4(%esp), %ecx130 .LCFI16:131 andl $-16, %esp132 pushl -4(%ecx)133 .LCFI17:134 pushl %ebp135 .LCFI18:136 movl %esp, %ebp137 .LCFI19:138 pushl %ecx139 .LCFI20:140 subl $36, %esp141 .LCFI21:142 movl $5, -8(%ebp)143 leal -9(%ebp), %eax144 movl %eax, (%esp)145 call _ZN1AC1Ev146 leal -8(%ebp), %eax147 movl %eax, 4(%esp)148 leal -9(%ebp), %eax149 movl %eax, (%esp)150 call _ZNK1A3fooEPi151 movl $1, %eax152 addl $36, %esp153 popl %ecx154 popl %ebp155 leal -4(%ecx), %esp156 ret157 .LFE1403:158 .size main, .-main159 .section .rodata160 .LC1:161 .string "foo"162 .text163 .align 2164 .globl _ZN1A3fooEPi165 .type _ZN1A3fooEPi, @function166 _ZN1A3fooEPi:167 .LFB1401:168 pushl %ebp169 .LCFI22:170 movl %esp, %ebp171 .LCFI23:172 subl $8, %esp173 .LCFI24:174 movl 12(%ebp), %eax175 movl (%eax), %eax176 movl %eax, 4(%esp)177 movl $_ZSt4cout, (%esp)178 call _ZNSolsEi179 movl $.LC1, 4(%esp)180 movl %eax, (%esp)181 call _ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc182 movl $_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_, 4(%esp)183 movl %eax, (%esp)184 call _ZNSolsEPFRSoS_E185 movl $1, %eax186 leave187 ret188 .LFE1401:189 .size _ZN1A3fooEPi, .-_ZN1A3fooEPi190 .local _ZSt8__ioinit191 .comm _ZSt8__ioinit,1,1192 .weakref _Z20__gthrw_pthread_oncePiPFvvE,pthread_once193 .weakref _Z27__gthrw_pthread_getspecificj,pthread_getspecific194 .weakref _Z27__gthrw_pthread_setspecificjPKv,pthread_setspecific195 .weakref _Z22__gthrw_pthread_createPmPK14pthread_attr_tPFPvS3_ES3_,pthread_create196 .weakref _Z22__gthrw_pthread_cancelm,pthread_cancel197 .weakref _Z26__gthrw_pthread_mutex_lockP15pthread_mutex_t,pthread_mutex_lock198 .weakref _Z29__gthrw_pthread_mutex_trylockP15pthread_mutex_t,pthread_mutex_trylock199 .weakref _Z28__gthrw_pthread_mutex_unlockP15pthread_mutex_t,pthread_mutex_unlock200 .weakref _Z26__gthrw_pthread_mutex_initP15pthread_mutex_tPK19pthread_mutexattr_t,pthread_mutex_init201 .weakref _Z26__gthrw_pthread_key_createPjPFvPvE,pthread_key_create202 .weakref _Z26__gthrw_pthread_key_deletej,pthread_key_delete203 .weakref _Z30__gthrw_pthread_mutexattr_initP19pthread_mutexattr_t,pthread_mutexattr_init204 .weakref _Z33__gthrw_pthread_mutexattr_settypeP19pthread_mutexattr_ti,pthread_mutexattr_settype205 .weakref _Z33__gthrw_pthread_mutexattr_destroyP19pthread_mutexattr_t,pthread_mutexattr_destroy206 .section .eh_frame,"a",@progbits207 .Lframe1:208 .long .LECIE1-.LSCIE1209 .LSCIE1:210 .long 0x0211 .byte 0x1212 .string "zP"213 .uleb128 0x1214 .sleb128 -4215 .byte 0x8216 .uleb128 0x5217 .byte 0x0218 .long __gxx_personality_v0219 .byte 0xc220 .uleb128 0x4221 .uleb128 0x4222 .byte 0x88223 .uleb128 0x1224 .align 4225 .LECIE1:226 .LSFDE5:227 .long .LEFDE5-.LASFDE5228 .LASFDE5:229 .long .LASFDE5-.Lframe1230 .long .LFB1411231 .long .LFE1411-.LFB1411232 .uleb128 0x0233 .byte 0x4234 .long .LCFI4-.LFB1411235 .byte 0xe236 .uleb128 0x8237 .byte 0x85238 .uleb128 0x2239 .byte 0x4240 .long .LCFI5-.LCFI4241 .byte 0xd242 .uleb128 0x5243 .align 4244 .LEFDE5:245 .LSFDE7:246 .long .LEFDE7-.LASFDE7247 .LASFDE7:248 .long .LASFDE7-.Lframe1249 .long .LFB1413250 .long .LFE1413-.LFB1413251 .uleb128 0x0252 .byte 0x4253 .long .LCFI7-.LFB1413254 .byte 0xe255 .uleb128 0x8256 .byte 0x85257 .uleb128 0x2258 .byte 0x4259 .long .LCFI8-.LCFI7260 .byte 0xd261 .uleb128 0x5262 .align 4263 .LEFDE7:264 .LSFDE9:265 .long .LEFDE9-.LASFDE9266 .LASFDE9:267 .long .LASFDE9-.Lframe1268 .long .LFB1412269 .long .LFE1412-.LFB1412270 .uleb128 0x0271 .byte 0x4272 .long .LCFI10-.LFB1412273 .byte 0xe274 .uleb128 0x8275 .byte 0x85276 .uleb128 0x2277 .byte 0x4278 .long .LCFI11-.LCFI10279 .byte 0xd280 .uleb128 0x5281 .align 4282 .LEFDE9:283 .LSFDE11:284 .long .LEFDE11-.LASFDE11285 .LASFDE11:286 .long .LASFDE11-.Lframe1287 .long .LFB1402288 .long .LFE1402-.LFB1402289 .uleb128 0x0290 .byte 0x4291 .long .LCFI13-.LFB1402292 .byte 0xe293 .uleb128 0x8294 .byte 0x85295 .uleb128 0x2296 .byte 0x4297 .long .LCFI14-.LCFI13298 .byte 0xd299 .uleb128 0x5300 .align 4301 .LEFDE11:302 .LSFDE13:303 .long .LEFDE13-.LASFDE13304 .LASFDE13:305 .long .LASFDE13-.Lframe1306 .long .LFB1403307 .long .LFE1403-.LFB1403308 .uleb128 0x0309 .byte 0x4310 .long .LCFI16-.LFB1403311 .byte 0xc312 .uleb128 0x1313 .uleb128 0x0314 .byte 0x9315 .uleb128 0x4316 .uleb128 0x1317 .byte 0x4318 .long .LCFI17-.LCFI16319 .byte 0xc320 .uleb128 0x4321 .uleb128 0x4322 .byte 0x4323 .long .LCFI18-.LCFI17324 .byte 0xe325 .uleb128 0x8326 .byte 0x85327 .uleb128 0x2328 .byte 0x4329 .long .LCFI19-.LCFI18330 .byte 0xd331 .uleb128 0x5332 .byte 0x4333 .long .LCFI20-.LCFI19334 .byte 0x84335 .uleb128 0x3336 .align 4337 .LEFDE13:338 .LSFDE15:339 .long .LEFDE15-.LASFDE15340 .LASFDE15:341 .long .LASFDE15-.Lframe1342 .long .LFB1401343 .long .LFE1401-.LFB1401344 .uleb128 0x0345 .byte 0x4346 .long .LCFI22-.LFB1401347 .byte 0xe348 .uleb128 0x8349 .byte 0x85350 .uleb128 0x2351 .byte 0x4352 .long .LCFI23-.LCFI22353 .byte 0xd354 .uleb128 0x5355 .align 4356 .LEFDE15:357 .ident "GCC: (GNU) 4.1.2 20070925 (Red Hat 4.1.2-33)"358 .section .note.GNU-stack,"",@progbits359
上面可以看到编译阶段的调用也是通过对重载函数的别名来实现的。
总结：
1.const重载主要是通过能否对传入的参数进行修改为判断的。
2.const参数重载和const函数重载机制都是一样的，因为对于const 函数重载可看做是对隐含的指针this的参数重载。
3.重载是在编译阶段已经完成，对于汇编和链接来说透明的。
原文链接: https://www.cnblogs.com/qingquan/archive/2010/10/21/1857444.html
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