warnings.txt

来自「开放源码的编译器open watcom 1.6.0版的源代码」· 文本 代码 · 共 158 行

- make string literals const char [] but allow (with warning) a conversion
  to char *
- local vars: warn if var was only "set" but never "used"
    - set: assigned to, &taken
    - used: r-value, &taken
- trigraph warning if trigraph is seen and we used the non-trigraph char
- float f;
  f != 0.1 (always true since ((double)(float)0.1) != 0.1)
  this was delayed because the user can't correct the problem
  via f != 0.1f since our float constants are not precisely
  correct (i.e., 0.1f==0.1d)
- signed/unsigned mismatches on relational+equality operators (promotions
  cause problems also)
  (need to consider constants for this one to eliminate spurious warnings)
  (combine with previous warning?)
    // microsoft does this (AFS)
    void foo(unsigned ui,int si,unsigned short sui,short ssi)
    {
	if( ui == si ) {	// signed/unsigned mismatch warning (3)
	    if( sui < ssi ) {	// signed/unsigned mismatch warning (3)
		++ui;
	    }
	}
    }
    enum U { X1 = 0, X2 = 0xa000 };
    enum S { X3 = -23, X4 = 34 };
    
    void foo( U x, S y )
    {
	if( x == y ) {
	}
    }
- an overriding virtual function doesn't match original w.r.t. default args
- an overriding virtual function doesn't match original w.r.t. throw specs
- complain about taking the address of a static function so that people
  that use overlays can be warned of potential problems (an overlay checking
  mode?)
- issue warning about "up and down" conversions
    char far *p;
    char far *q;

    void foo( void )
    {
        q = (char *) p;
    }
- the concatenated string literal warning (during init) should try to be
  smarter and only warn if the next field is a char *

- warn when inline'd in declaration and not in definition; e.g.,
    struct S {
        int a;
        inline S();
    };

    S::S()
    {
        a = 0;
    }

- provide extra info in case programmer wants to override functions but just
  got them wrong
  struct S {
  };
  
  void foo( S x )
  {
    x++;	// info if ++@ is available
    x[t];	// info if any [] are available
  }
- warn about fields that are used before they are initialized in a ctor
- warn if a object is initialized but not subsequently referenced (level 9?)
- warn if all enumerators are not checked in a switch statment with a enum
  control expression
- warn if a structure is passed to the *printf class of ANSI C CLIB fns
- better error message for this case
	struct foo {
	    foo( int a );	// foo has a ctor
	};
				
	struct bar : public foo {
	    bar( int b );
	    
	    foo mem;
	    int _b;
	};

	bar::bar( int b ) : foo( b ), _b( b ) // no mem(b) in mem-init!
	{
	}

// (14,1): Error! E390: cannot generate default constructor to initialize 'foo' since constructors were declared

When I first got this error, it was from adding a constructor to a
member of another class.  I looked at the error and the class, and I
thought there was a problem constructing the bar class, when actually
the error points to no constructor for the "mem" member of bar.

I think it might be better if somehow the member name were mentioned,
especially since the line number of the error does not point to mem
(which is not in the constructor list).

- warn about "sign-loss" in addition to "bit-loss"
// we were getting a truncation warning but it seems to have gone away
#include <stddef.h>
#ifdef __cplusplus
#include <iostream.h>
#endif
#include <string.h>
#include <stdio.h>

#if 1
typedef char CHAR;
#else
typedef unsigned char CHAR;
#endif

CHAR name[] = "Mark\n";

void func(unsigned int x);

main()
{
        char Name[16];
        char c = -1;
        int x = 0;
#ifdef __386__
        signed int y = 4294967295;
        unsigned int z = 4294967295;
#else
        signed int y = 65535;
        unsigned int z = 65535;
#endif

#if 1
        func(z);
        func(y);

        x = y;
        z = y;
        y = z;
#endif

        printf("x %d   y %d    z %d\n", x, y, z);
        printf("sizeof %d\n", sizeof(int));

        strcpy(Name, name);

#if 0
        cout << Name;
#endif
}

void
func(int x)
{
        printf("==%d==\n", x);
}