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Fix replace-buffer-contents undefined behavior

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* src/editfns.c (Freplace_buffer_contents): Avoid undefined
behavior with competing side effects in parallel subexpressions.
Problem reported by Apple clang version 12.0.0 (clang-1200.0.32.29).
This commit is contained in:
Paul Eggert 2021-03-21 18:08:13 -07:00
parent 720a8b17f8
commit 6a4ed891d8
1 changed files with 4 additions and 2 deletions
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6
src/editfns.c
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@ -2053,6 +2053,8 @@ nil. */)
code. */
ptrdiff_t del_bytes = (size_t) size_a / CHAR_BIT + 1;
ptrdiff_t ins_bytes = (size_t) size_b / CHAR_BIT + 1;
unsigned char *deletions = SAFE_ALLOCA (del_bytes);
unsigned char *insertions = SAFE_ALLOCA (ins_bytes);
struct context ctx = {
.buffer_a = a,
.buffer_b = b,
@ -2060,8 +2062,8 @@ nil. */)
.beg_b = min_b,
.a_unibyte = BUF_ZV (a) == BUF_ZV_BYTE (a),
.b_unibyte = BUF_ZV (b) == BUF_ZV_BYTE (b),
.deletions = SAFE_ALLOCA (del_bytes),
.insertions = SAFE_ALLOCA (ins_bytes),
.deletions = deletions,
.insertions = insertions,
.fdiag = buffer + size_b + 1,
.bdiag = buffer + diags + size_b + 1,
.heuristic = true,