From: Matthew Fernandez <matthew.fernandez@gmail.com>
Date: Thu, 3 Nov 2022 04:25:47 +0000 (-0700)
Subject: cdt: make intent to coerce to unsigned clearer in 'dtstrhash'
X-Git-Tag: 7.0.1~4^2~3
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8f938136270a4bf89d4871bcff675e319e48a9b5;p=graphviz

cdt: make intent to coerce to unsigned clearer in 'dtstrhash'

This squashes some compiler warnings on CentOS 7:

  dtstrhash.c: In function 'dtstrhash':
  dtstrhash.c:22:18: warning: conversion to 'unsigned int' from 'int' may change
    the sign of the result [-Wsign-conversion]
      h = (h + (s[0]<<8) + s[1])*DT_PRIME;
                    ^
  dtstrhash.c:28:18: warning: conversion to 'unsigned int' from 'int' may change
    the sign of the result [-Wsign-conversion]
      h = (h + (s[0]<<8) + s[1])*DT_PRIME;
                    ^
  dtstrhash.c:30:18: warning: conversion to 'unsigned int' from 'int' may change
    the sign of the result [-Wsign-conversion]
      h = (h + (s[0]<<8))*DT_PRIME;
---

diff --git a/lib/cdt/dtstrhash.c b/lib/cdt/dtstrhash.c
index f00394038..41c99d3db 100644
--- a/lib/cdt/dtstrhash.c
+++ b/lib/cdt/dtstrhash.c
@@ -19,15 +19,15 @@ uint dtstrhash(uint h, void* args, int n)
 
 	if(n <= 0)
 	{	for(; *s != 0; s += s[1] ? 2 : 1)
-			h = (h + (s[0]<<8) + s[1])*DT_PRIME;
+			h = (h + ((unsigned)s[0] << 8u) + (unsigned)s[1]) * DT_PRIME;
 		n = s - (unsigned char*)args;
 	}
 	else
 	{	unsigned char*	ends;
 		for(ends = s+n-1; s < ends; s += 2)
-			h = (h + (s[0]<<8) + s[1])*DT_PRIME;
+			h = (h + ((unsigned)s[0] << 8u) + (unsigned)s[1]) * DT_PRIME;
 		if(s <= ends)
-			h = (h + (s[0]<<8))*DT_PRIME;
+			h = (h + ((unsigned)s[0] << 8u)) * DT_PRIME;
 	}
 	return (h+n)*DT_PRIME;
 }