ときどきの雑記帖 RE* (新南口)

迫る初夏

アカツメクサというのもあるのを初めて知った。 シロツメクサの漢字表記はちょっと前に。

レガシークエル

という言葉があるらしい (意味は各自で調べて😄)

メモ

gnulib

コンパイラーによってあれやらこれの(謎) 置ける場所に違いがあったりするらしい。 めんどくせー

gnulib-common.m4 « m4 - gnulib.git - gnulib - GNU portability library

#ifdef __cplusplus
# define CC "C"
#else
# define CC
#endif

#define ND   [[__nodiscard__]]
#define WUR  __attribute__((__warn_unused_result__))
gcc clang g++ clang++
ND int foo (int);
int ND foo (int); warn error warn error
int foo ND (int);
int foo (int) ND; warn error warn error
gcc clang g++ clang++
WUR int foo (int);
int WUR foo (int);
int fo1 WUR (int); error error error error
int foo (int) WUR;
gcc clang g++ clang++
ND extern CC int foo (int); error error
extern CC ND int foo (int); error error
extern CC int ND foo (int); warn error warn error
extern CC int foo ND (int);
extern CC int foo (int) ND; warn error warn error
gcc clang g++ clang++
WUR extern CC int foo (int); warn
extern CC WUR int foo (int);
extern CC int WUR foo (int);
extern CC int foo WUR (int); error error error error
extern CC int foo (int) WUR;
gcc clang g++ clang++
ND EXTERN_C_FUNC int foo (int); error error
EXTERN_C_FUNC ND int foo (int);
EXTERN_C_FUNC int ND foo (int); warn error warn error
EXTERN_C_FUNC int foo ND (int);
EXTERN_C_FUNC int foo (int) ND; warn error warn error
gcc clang g++ clang++
WUR EXTERN_C_FUNC int foo (int); warn
EXTERN_C_FUNC WUR int foo (int);
EXTERN_C_FUNC int WUR foo (int);
EXTERN_C_FUNC int fo2 WUR (int); error error error error
EXTERN_C_FUNC int foo (int) WUR; 
#ifdef __cplusplus
# define CC "C"
#else
# define CC
#endif

#define BD   [[__deprecated__]]
#define AD   __attribute__ ((__deprecated__))
gcc clang g++ clang++
BD extern CC int var; error errorn
extern CC BD int var; error error
extern CC int BD var; warn error warn error
extern CC int var BD;
gcc clang g++ clang++
AD extern CC int var; warn
extern CC AD int var;
extern CC int AD var;
extern CC int var AD;
gcc clang g++ clang++
BD extern CC int z[]; error error
extern CC BD int z[]; error error
extern CC int BD z[]; warn error warn error
extern CC int z1 BD [];
extern CC int z[] BD; warn error error
gcc clang g++ clang++
AD extern CC int z[]; warn
extern CC AD int z[];
extern CC int AD z[];
extern CC int z2 AD []; error error error error
extern CC int z[] AD;

WG 14

WG 14 Document log
N3889 2026/05/10 Meneide, _Any_func* - - A Universal Function Pointer Storage Type, r5
N3888 2026/05/10 Meneide, Expression Evaluation and Access in _Generic, r1
N3880 2026/05/10 Munger, Memory allocation with size feedback v3

why c function pointer is not compatible with void pointer

void *を関数ポインターにキャストするのは その結果が保証されているわけではない。 というのはそこそこ知られていることではあるけれども、 なんでだろうと思ってえーあいに聞いたところ 「void *はオブジェクト(データ)を指し示すものだけど 関数ポインターはオブジェクトではないから」 みたいな回答が返ってきた。

それっぽい回答だなと思いつつもう少し突っ込んでみると、 POSIX のdlym(3)の項に そういう変換ができるようにすべし みたいなことが書いてあると。

dlsym

EXAMPLES

The following example shows how dlopen() and dlsym() can be used to access either function or data objects. For simplicity, error checking has been omitted.


   void    *handle;
   int     *iptr, (*fptr)(int);


   /* open the needed object */
   handle = dlopen("/usr/home/me/libfoo.so", RTLD_LOCAL | RTLD_LAZY);


   /* find the address of function and data objects */
   *(void **)(&fptr) = dlsym(handle, "my_function");
   iptr = (int *)dlsym(handle, "my_object");

   /* invoke function, passing value of integer as a parameter */
   (*fptr)(*iptr);

RATIONALE

The ISO C standard does not require that pointers to functions can be cast back and forth to pointers to data. Indeed, the ISO C standard does not require that an object of type void * can hold a pointer to a function. Implementations supporting the XSI extension, however, do require that an object of type void * can hold a pointer to a function. The result of converting a pointer to a function into a pointer to another data type (except void *) is still undefined, however. Note that compilers conforming to the ISO C standard are required to generate a warning if a conversion from a void * pointer to a function pointer is attempted as in:

   fptr = (int (*)(int))dlsym(handle, "my_function");

Due to the problem noted here, a future version may either add a new function to return function pointers, or the current interface may be deprecated in favor of two new functions: one that returns data pointers and the other that returns function pointers.

新刊近刊

awk

CONVFMT

CONVFMTに数値と関係ない書式指定を設定するとどうなるか。 POSIX的にはどうなんだろうと調べてみると、 言及してはいても

The Open Group Base Specifications Issue 8

A numeric value that is exactly equal to the value of an integer (see 1.1.2 Concepts Derived from the ISO C Standard) shall be converted to a string by the equivalent of a call to the sprintf function (see String Functions) with the string “%d” as the fmt argument and the numeric value being converted as the first and only expr argument. Any other numeric value shall be converted to a string by the equivalent of a call to the sprintf function with the value of the variable CONVFMT as the fmt argument and the numeric value being converted as the first and only expr argument. The result of the conversion is unspecified if the value of CONVFMT is not a floating-point format specification. This volume of POSIX.1-2024 specifies no explicit conversions between numbers and strings. An application can force an expression to be treated as a number by adding zero to it, or can force it to be treated as a string by concatenating the null string ("") to it.

The result of the conversion is unspecified if the value of CONVFMT is not a floating-point format specification.

MinRX

パッチが出ていたけど

Subject: [PATCH] Fix bug in charset that caused incorrect firstbytes computation

diff --git a/charset.c b/charset.c
index 952828e..d2df563 100644
--- a/charset.c
+++ b/charset.c
@@ -8990,32 +8990,18 @@ charset_finalize(charset_t *set)
                qsort(set->items, set->nelems,
                        sizeof(set_item), item_compare_for_sorting);

-       // condense it
+       // coalesce adjacent items that have no gaps between them (or that actually overlap)
+       #ifndef MAX
+       #define MAX(A, B) ((A) >= (B) ? (A) : (B))
+       #endif
        set_item *items = set->items;
-       for (i = 0, j = 1; j < set->nelems; i++, j++) {
-               bool need_shift = false;
-               if (items[i].start == items[j].start && items[i].end == items[j].end) {
-                       need_shift = true;
-               } else if (items[i].end + 1 == items[j].start) {
-                       items[i].end = items[j].end;
-                       need_shift = true;
-               } else if (items[i].start < items[j].start && items[i].end > items[j].end) {
-                       need_shift = true;
-               } else if (   items[i].start <= items[j].start
-                          && items[i].end > items[j].start
-                          && items[j].end >= items[i].end) {
-                       items[i].end = items[j].end;
-                       need_shift = true;
-               }
-               if (need_shift) {
-                       for (size_t k = j + 1; k < set->nelems; j++, k++)
-                               items[j] = items[k];
-                       
-                       set->nelems--;
-                       i--;    // compensate for loop, continue checking at current position
-                       j = i + 1;
-               }
-               // otherwise, just continue around the loop
+       if (set->nelems != 0) {
+               for (i = 1, j = 1; j < set->nelems; j++)
+                       if (items[i - 1].end + 1 >= items[j].start)
+                               items[i - 1].end = MAX(items[i - 1].end, items[j].end);
+                       else
+                               items[i++] = items[j];
+               set->nelems = i;
        }
        set->nelems8bit = set->nelems;
        for (size_t i = 0; i < set->nelems; i++) {

なんでこれで治るの?🤔

misc

マ

ざわざわ…というか

「…マ?」

みたいな反応だったかなあ 自分の周りでは

あとイラストではジョリバを探した(笑)

全部やった😄 インベーダー以外の3代は家の近くにあった 駄菓子屋の店頭に置かれてたな

Q

mermaid

フローチャートの分岐もどうにかならんかなあ(他人頼み)

シロツメクサの花が咲いたら ≪ prev