编译带有脚本的SDL / SDL2会导致重新定义错误

问题描述 投票：1回答：1

tl; dr使用-s USE_SDL=2 -s USE_SDL_IMAGE=2 -s SDL2_IMAGE_FORMATS='["png"]' -s USE_SDL_TTF=2与SDL2一起编译C代码会在arch linux上产生很多“ redefinition error”。

我正在尝试使用emscripten在浏览器中使用SDL2，但它完全失败。我正在遵循this关于一个简单的SDL2脚本的指南，该脚本会在周围移动一个黄色正方形。该示例可在他的Web浏览器上使用。用gcc在本地编译代码可以很好地工作，并且可以按预期工作。

我当前正在运行Arch Linux，并且已经安装了所有依赖项（SDL2，emscripten，emsdk，lib32-sdl2，sdl2_image，sdl2_ttf）。我最初只是按照说明通过git安装和安装了SDL2并通过git安装了emscripten和emsdk，但是当该方法不起作用时，我尝试通过回购协议安装其余的东西。和AUR。仍然无济于事。我现在已经卸载了列出的每个软件包并重新安装了SDL2，现在我仅使用git安装，如下所示

运行make em以使用脚本编译脚本失败，并导致以下错误：

/home/user/gitclones/emsdk/upstream/emscripten/cache/wasm/include/SDL2/SDL_error.h:41:29: note: previous declaration is here
extern DECLSPEC int SDLCALL SDL_SetError(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) SDL_PRINTF_VARARG_FUNC(1);
                            ^
In file included from main.c:7:
In file included from /home/user/gitclones/emsdk/upstream/emscripten/system/include/SDL/SDL_ttf.h:30:
In file included from /home/user/gitclones/emsdk/upstream/emscripten/system/include/SDL/SDL.h:76:
In file included from /home/user/gitclones/emsdk/upstream/emscripten/system/include/SDL/SDL_audio.h:32:
/home/user/gitclones/emsdk/upstream/emscripten/system/include/SDL/SDL_error.h:57:5: error: redefinition of enumerator 'SDL_ENOMEM'
    SDL_ENOMEM,
    ^
/home/user/gitclones/emsdk/upstream/emscripten/cache/wasm/include/SDL2/SDL_error.h:57:5: note: previous definition is here
    SDL_ENOMEM,
    ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
emcc: error: '/home/user/gitclones/emsdk/upstream/bin/clang -target wasm32-unknown-emscripten -D__EMSCRIPTEN_major__=1 -D__EMSCRIPTEN_minor__=39 -D__EMSCRIPTEN_tiny__=16 -D_LIBCPP_ABI_VERSION=2 -Dunix -D__unix -D__unix__ -Werror=implicit-function-declaration -Xclang -nostdsysteminc -Xclang -isystem/home/user/gitclones/emsdk/upstream/emscripten/system/include/compat -Xclang -isystem/home/user/gitclones/emsdk/upstream/emscripten/system/include -Xclang -isystem/home/user/gitclones/emsdk/upstream/emscripten/system/include/libc -Xclang -isystem/home/user/gitclones/emsdk/upstream/emscripten/system/lib/libc/musl/arch/emscripten -Xclang -isystem/home/user/gitclones/emsdk/upstream/emscripten/system/local/include -Xclang -isystem/home/user/gitclones/emsdk/upstream/emscripten/cache/wasm/include -DEMSCRIPTEN -fignore-exceptions -O3 main.c -Xclang -isystem/home/user/gitclones/emsdk/upstream/emscripten/cache/wasm/include/SDL2 -I/home/user/gitclones/emsdk/upstream/emscripten/cache/wasm/include/freetype2/freetype -c -o /tmp/emscripten_temp_yax02_qn/main_0.o -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr' failed (1)

main.c

#include <stdio.h>
#include <stdlib.h>

#if __EMSCRIPTEN__
#include <emscripten/emscripten.h>
#include <SDL2/SDL.h>
#include <SDL/SDL_ttf.h>
#else
#include <SDL2/SDL.h>
#include <SDL2/SDL_ttf.h>
#endif

#define SCREEN_WIDTH  200
#define SCREEN_HEIGHT 200

SDL_Window *window = NULL;
SDL_Renderer *renderer = NULL;

#define MAX(a,b) ((a) > (b) ? a : b)
#define MIN(a,b) ((a) < (b) ? a : b)

int posX=0;
int posY=0;
int sizeW=20;
int sizeH=20;

static int quit = 0;

void render()
{

    SDL_Rect r_scr;
    r_scr.x = posX;
    r_scr.y = posY;
    r_scr.w = sizeW;
    r_scr.h = sizeH;
    SDL_SetRenderDrawColor( renderer, 0x00, 0x00, 0x00, 0xFF );
    SDL_RenderClear(renderer);

    SDL_SetRenderDrawColor(renderer, 0xff, 0xff, 0x00, 0x00);
    SDL_RenderDrawRect(renderer, &r_scr);
    SDL_RenderPresent(renderer);
}

#if __EMSCRIPTEN__
void main_tick() {
#else
int main_tick() {
#endif

    SDL_Event event;

        while (SDL_PollEvent(&event))
        {
            switch (event.type)
            {
            case SDL_QUIT:
            {
                quit = 1;
                break;
            }
            case SDL_KEYDOWN:
            {
                switch (event.key.keysym.sym)
                {
                case SDLK_UP:
                {
                    if (posY>=20)
                    {
                        posY-=20;
                    }
                    break;
                }
                case SDLK_DOWN:
                {
                    if (posY+sizeH<SCREEN_HEIGHT)
                    {
                        posY += 20;
                    }
                    break;
                }
                case SDLK_LEFT:
                {
                    if (posX>=20)
                    {
                        posX-=20;
                    }
                    break;
                }
                case SDLK_RIGHT:
                {
                    if (posX+sizeW<SCREEN_WIDTH)
                    {
                        posX+=20;
                    }
                    break;
                }
                }
                break;
            }
            }

        }


    render();
    SDL_UpdateWindowSurface(window);

#if !__EMSCRIPTEN__
    return 0;
#endif
}

void main_loop()
{

#if __EMSCRIPTEN__
    emscripten_set_main_loop(main_tick, -1, 1);
#else
    while (0 == quit)
    {
        main_tick();
    }
#endif
}

int main()
{
    SDL_Init(SDL_INIT_VIDEO);

    window = SDL_CreateWindow(
        "WEBASM",
        SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
        SCREEN_WIDTH, SCREEN_HEIGHT,
        SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL);

    renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    SDL_SetRenderDrawColor(renderer, 0xff, 0xff, 0xff, 0xff);

    main_loop();

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}

index.html

<html>
    <head>
        <meta charset="utf-8">
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    </head>
    <body>
        <script type='text/javascript'>
          var Module = {};
          fetch('index.wasm')
            .then(response =>
              response.arrayBuffer()
            ).then(buffer => {
              Module.canvas = document.getElementById("canvas");
              Module.wasmBinary = buffer;
              var script = document.createElement('script');
              script.src = "index.js";
              script.onload = function() {
                console.log("Emscripten boilerplate loaded.")
              }
              document.body.appendChild(script);
            });
        </script>
        <canvas id="canvas" style="width:100%; height:100%"></canvas>

    </body>
</html>

Makefile

CC=gcc
CFALGS=
LDFLAGS=-lSDL2 -lSDL2_ttf

EM_ENV=LLVM=/usr/bin NODE_JS=node EMSCRIPTEN_ROOT=/usr/lib/emscripten
EM_CC=emcc
EM_CFLAGS=-s WASM=1 -O3
EM_LDFALGS=-s USE_SDL=2 -s USE_SDL_IMAGE=2 -s SDL2_IMAGE_FORMATS='["png"]' -s USE_SDL_TTF=2

pc:
    $(CC) $(CFLAGS) $(LDFLAGS) main.c -o main

em:
    $(EM_CC) main.c $(EM_CFLAGS) $(EM_LDFALGS) -o index.js -s EXTRA_EXPORTED_RUNTIME_METHODS='["ccall", "cwrap"]'

与其他标志（例如-O1或-USE_SDL = 1）一起编译会导致相同的错误。

值得一提：编译并运行timhutton的示例非常好]

编辑：

emcc -v

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 1.39.16
clang version 11.0.0 (/b/s/w/ir/cache/git/chromium.googlesource.com-external-gec77df5e957828ca0475aa3d566977b)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/user/gitclones/emsdk/upstream/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-pc-linux-gnu/10.1.0
Found candidate GCC installation: /usr/lib64/gcc/x86_64-pc-linux-gnu/10.1.0
Selected GCC installation: /usr/lib64/gcc/x86_64-pc-linux-gnu/10.1.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
shared:INFO: (Emscripten: Running sanity checks)
c linux sdl sdl-2 emscripten
1个回答
0
投票

哈哈通过更改解决了它>

#if __EMSCRIPTEN__
#include <emscripten/emscripten.h>
#include <SDL2/SDL.h>
#include <SDL/SDL_ttf.h>
#else
#include <SDL2/SDL.h>
#include <SDL2/SDL_ttf.h>
#endif

to
#if __EMSCRIPTEN__
#include <emscripten/emscripten.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_ttf.h>
#else
#include <SDL2/SDL.h>
#include <SDL2/SDL_ttf.h>
#endif

不同之处在于，许多示例在线使用#include <SDL/SDL_ttf.h>，由于某种原因，这种情况在我这种情况下不起作用。该演示甚至在其代码中都有两个版本。在包含标题的情况下，在任何斜杠（/）之前将SDL更改为SDL2：）
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