ときどきの雑記帖 RE* (新南口)

More Than Human

PascalABC.net

.NETを使ったPascal?

Tcl

500行でどこまでの機能を実装しているんだろう

LLM policy

I would like to propose a policy regarding LLM regenerated code in Gnulib.

メモ。

Lisp

WG 14

WG 14 Document log

配列関連のものが結構あった

n3800

n3800, alx-0078r3 - [static n] shouldn’t access more than n elements

Abstract

The following function prototype requires an input with at least 2 elements:

  void f(int a[static 2]);

It should not use more than 2 elements, as those are not guaranteed to be available. That is, the following function definition should be unacceptable:

  void f(int a[static 2])
  {
  	a[7] = 0;
  }

n3801

[n3801, alx-0079r3 - [static n] == non-null\ n]

Abstract

Everyone who has ever written [2] in an array parameter meant what a 10-year-old kid would guess. Let’s acknowledge it.

	void f(int a[2]);

Prior art

GCC acknowledges this common understanding, and diagnoses such code:

  alx@devuan:~/tmp$ cat ap.c 
  void f(int a[2]);
  int
  main(void)
  {
  	int a[1];
  	f(a);
  }
  alx@devuan:~/tmp$ gcc -S ap.c
  ap.c: In function ‘main’:
  ap.c:6:9: warning: ‘f’ accessing 8 bytes in a region of size 4 [-Wstringop-overflow=]
      6 |         f(a);
        |         ^~~~
  ap.c:6:9: note: referencing argument 1 of type ‘int[2]’
  ap.c:1:6: note: in a call to function ‘f’
      1 | void f(int a[2]);
        |      ^

n3802

n3802, alx-0081r3 - array parameters of 0 elements

However, that would result in UB for the call above, as the number of elements isn’t allowed to be zero.

‘static’ in [static n] has a different meaning (see also alx-0079): it says that the argument shall be non-null.

Discussion

The following code is valid:

  static inline wchar_t
  my_wmemset(size_t n, wchar_t *wcs, wchar_t wc)
  {
  	return wmemset(wcs, wc, n);
  }

  wchar_t  a[42];

  my_wmemset(0, a + 42, L'x');

It would be natural to be able to declare my_wmemset() as

  wchar_t my_wmemset(size_t n, wchar_t wcs[static n], wchar_t);

However, that would result in UB for the call above, as the number of elements isn’t allowed to be zero. That restriction is superfluous, and harmful; let’s remove it.

これって未定義動作だったのね

n3803

n3803, alx-0080r2 - [static] without array length expression

Abstract

‘static’ in [static n] means that the argument shall be non-null. That is entirely independent of the length of the array parameter, so it doesn’t make sense requiring the length to be specified. Lift that restriction.

それはそう。＞That is entirely independent of the length of the array parameter

新刊近刊

ギャラリーフェイク

17日発売のビッグコミック増刊に掲載されたギャラリーフェイクの最新回、 好きな画家が二人同時に取り上げられてびっくり。

作中の高田美術館での企画展、どこかでやってくんないかな😄

本を読めなくなった人たち

ほかにもいくつか言及している投稿を見かけたので ちょっと見てみよう

awk

gawk

Prepare next test tarball. - gawk.git - gawk

リリースももうじきですかね

Update README.matchers with known issues. - gawk.git - gawk

追記された部分を見ると

+When ignoring case, in locales where more than one lower-case
+character maps to the same upper-case character, MinRX does
+not currently do the right thing.  This is being worked on
+and should be fixed in the first patch.
+
+Similarly, there are some unusual locales where [:digit:] may
+not correctly match digits. This is also being worked on
+and should be fixed in the first patch.

それはまあ。という感じではある。

そういや読もう読もうと思いながら 全然手を付けてない＞MiｎRX

計算(機)の歴史を限界まで語るBAR

上野かあ

FM-7

入力

パンチカードとオープンリールのテープは使ったことあるな😄

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