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Groups > gnu.bash.bug > #15041

[PATCH 3/3] Fix incompatible pointer type warning in unicode.c

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The warning is raised by Clang (7.0.1-4) when sizeof(wchar_t) is 4

| dualbus@system76-pc:~/src/gnu/bash/lib/sh$ make unicode.o
| clang -c   -I. -I../.. -I../.. -I../../lib -I../../include -I.  -DHAVE_CONFIG_H -DSHELL  -ggdb -O0 -Wno-parentheses -Wno-format-security   unicode.c
| unicode.c:262:69: warning: incompatible pointer types passing 'wchar_t [3]' to parameter of type 'unsigned short *' [-Wincompatible-pointer-types]
|   else if (sizeof (wchar_t) == 2 && c <= 0x10ffff && u32toutf16 (c, ws))
|                                                                     ^~
| 1 warning generated.

dualbus@system76-pc:~/src/gnu/bash$ clang -v 2>&1 | head -n2
clang version 7.0.1-4 (tags/RELEASE_701/final)
Target: x86_64-pc-linux-gnu

In practice, this isn't really a problem because the compiler should optimize
away the `sizeof(wchar_t) == 2' branch. Still, it's easy to fix.

I think that maybe there should be some sort of compile-time assertion inside
`u32toutf16`, to ensure it's only used when `sizeof(wchar_t) == 2', but I don't
know how to do that.
---
 lib/sh/unicode.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/sh/unicode.c b/lib/sh/unicode.c
index fe13c4a0..99c422ab 100644
--- a/lib/sh/unicode.c
+++ b/lib/sh/unicode.c
@@ -216,21 +216,21 @@ u32toutf8 (wc, s)
 int
 u32toutf16 (c, s)
      u_bits32_t c;
-     unsigned short *s;
+     wchar_t *s;
 {
   int l;
 
   l = 0;
   if (c < 0x0d800 || (c >= 0x0e000 && c <= 0x0ffff))
     {
-      s[0] = (unsigned short) (c & 0xFFFF);
+      s[0] = (wchar_t) (c & 0xFFFF);
       l = 1;
     }
   else if (c >= 0x10000 && c <= 0x010ffff)
     {
       c -= 0x010000;
-      s[0] = (unsigned short)((c >> 10) + 0xd800);
-      s[1] = (unsigned short)((c & 0x3ff) + 0xdc00);
+      s[0] = (wchar_t)((c >> 10) + 0xd800);
+      s[1] = (wchar_t)((c & 0x3ff) + 0xdc00);
       l = 2;
     }
   s[l] = 0;
-- 
2.20.1

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[PATCH 3/3] Fix incompatible pointer type warning in unicode.c Eduardo A. Bustamante López <dualbus@gmail.com> - 2019-01-04 12:25 -0800

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