c - 为什么 emacs 会显示这些警告和错误？

Question

我正在尝试从 VIM 切换到 Emacs，但我无法让语法检查器为小型 C 项目工作。我已经尝试将 Flymake 和 Flycheck 作为语法检查器，但都显示不存在的编译器错误。我目前有 3 个文件，poker.c cards.c 和 cards.h。

这里是 poker.c

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

int main()
{

  struct Deck *deck = malloc(sizeof(struct Deck)); 
  struct Hand *hand = malloc(sizeof(struct Hand));
   clear_deck(deck);
  deck = init_deck(deck);
  deck = shuffle(deck);
  int c = deal(deck, hand);
  if(c != 5) {
    printf("error: not enough cards delt");
  } else {
    print_hand(hand);
  }
  return 0;
}

这是 cards.h

typedef enum {
  TWO,
  THREE,
  FOUR,
  FIVE,
  SIX,
  SEVEN,
  EIGHT,
  NINE,
  TEN,
  JACK,
  QUEEN,
  KING,
  ACE,
} Rank;


typedef enum {
  SPADES,
  CLUBS,
  HEARTS,
  DIAMONDS,
} Suit;

struct Card {
  Rank rank;
  Suit suit;
  int shuffled;
};

struct Deck {
  struct Card cards[52];
  int shuffled;
};

struct Hand{
  struct Card cards[5];
};

void * shuffle(struct Deck *deck);
void * init_deck(struct Deck *d);
void clear_deck(struct Deck *d);
void print_deck(struct Deck *d);
void print_hand(struct Hand *h);
int deal(struct Deck *deck, struct Hand *hand);

两个语法检查器都显示该行有错误

  struct Hand *hand = malloc(sizeof(struct Hand));

以及所有其他功能的警告。这是 *Flycheck errors* 缓冲区

    9  37 error           invalid application of ‘sizeof’ to incomplete type ‘struct Hand’... (c/c++-gcc)
   10   4 warning         implicit declaration of function ‘clear_deck’... (c/c++-gcc)
   11   3 warning         implicit declaration of function ‘init_deck’... (c/c++-gcc)
   11   8 warning         assignment makes pointer from integer without a cast... (c/c++-gcc)
   12   3 warning         implicit declaration of function ‘shuffle’... (c/c++-gcc)
   12   8 warning         assignment makes pointer from integer without a cast... (c/c++-gcc)
   13   3 warning         implicit declaration of function ‘deal’... (c/c++-gcc)
   17   5 warning         implicit declaration of function ‘print_hand’... (c/c++-gcc)

我觉得 emacs 在进行语法检查之前没有运行 C 预处理器。我可以做些什么来使语法检查器正常工作吗？

Answer 1

除其他事项外，头文件:cards.h 需要有一个“include guard”建议

#ifndef CARDS_H
#define CARDS_H

typedef enum {
  TWO,
  THREE,
  FOUR,
  FIVE,
  SIX,
  SEVEN,
  EIGHT,
  NINE,
  TEN,
  JACK,
  QUEEN,
  KING,
  ACE,
} Rank;


typedef enum {
  SPADES,
  CLUBS,
  HEARTS,
  DIAMONDS,
} Suit;

struct Card {
  Rank rank;
  Suit suit;
  int shuffled;
};

struct Deck {
  struct Card cards[52];
  int shuffled;
};

struct Hand{
  struct Card cards[5];
};

void * shuffle(struct Deck *deck);
void * init_deck(struct Deck *d);
void clear_deck(struct Deck *d);
void print_deck(struct Deck *d);
void print_hand(struct Hand *h);
int deal(struct Deck *deck, struct Hand *hand);

#endif // CARDS_H

我编译的文件:poker.c 添加错误检查。

启用所有警告(linux ubuntu 14.04 和 gcc -Wall -Wextra -pedantic ...)

它编译得很干净。

这是我编译的代码。

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

int main()
{
    struct Deck *deck = malloc(sizeof(struct Deck)); 
    if( NULL == deck )
    { // then malloc failed
        perror( "malloc for deck failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, malloc successful

    struct Hand *hand = malloc(sizeof(struct Hand));
    if( NULL == hand )
    { // then, malloc failed
        perror("malloc for hand failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, malloc successful

    clear_deck(deck);
    deck = init_deck(deck);
    deck = shuffle(deck);
    int c = deal(deck, hand);

    if(c != 5) 
    {
        printf("error: not enough cards delt\n"); // \n so will immediate be output

    } 

    else 
    {
        print_hand(hand);
    }

    return 0;
} // end function: main