[PATCH] Silence -Wshift-count-overflow warnings

[Jan Dubiec]

This patch fixes a few "left shift count >= width of type
[-Wshift-count-overflow]" warnings. Before shifting a char 16 (or more)
bits left first it explicitly casts the char to uint32_t. The existing
code relies on implicit casts to int and assumes that ints are 32-bit.
This is not always true because the C standard does not require int to
be 32-bit and there are targets (e.g. H8/300) where by default int is
indeed 16-bit.

2025-03-02  Jan Dubiec  <jdx@o2.pl>

newlib/ChangeLog:

	* libc/stdlib/gdtoa-gdtoa.c (gdtoa): Cast to __ULong before left shift.
	* libc/string/memmem.c (memmem): Cast to uint32_t before left shift.
	* libc/string/strstr.c (strstr2): Ditto.
	(strstr3): Ditto.
	(strstr4): Ditto.
-------------- next part --------------
 newlib/libc/stdlib/gdtoa-gdtoa.c | 2 +-
 newlib/libc/string/memmem.c      | 3 ++-
 newlib/libc/string/strstr.c      | 6 +++---
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/newlib/libc/stdlib/gdtoa-gdtoa.c b/newlib/libc/stdlib/gdtoa-gdtoa.c
index da2338c48..d29a81eab 100644
--- a/newlib/libc/stdlib/gdtoa-gdtoa.c
+++ b/newlib/libc/stdlib/gdtoa-gdtoa.c
@@ -261,7 +261,7 @@ gdtoa
 		dval(d) *= 1 << j1;
 	word0(d) += j << Exp_shift - 2 & Exp_mask;
 #else
-	word0(d) += (be + bbits - 1) << Exp_shift;
+	word0(d) += (__ULong)(be + bbits - 1) << Exp_shift;
 #endif
 	if (k >= 0 && k <= Ten_pmax) {
 		if (dval(d) < tens[k])
diff --git a/newlib/libc/string/memmem.c b/newlib/libc/string/memmem.c
index 65267b9c5..13d8c0a9f 100644
--- a/newlib/libc/string/memmem.c
+++ b/newlib/libc/string/memmem.c
@@ -129,7 +129,8 @@ memmem (const void *haystack, size_t hs_len, const void *needle, size_t ne_len)
 
   if (ne_len == 2)
     {
-      uint32_t nw = ne[0] << 16 | ne[1], hw = hs[0] << 16 | hs[1];
+      uint32_t nw = ((uint32_t)ne[0] << 16) | ne[1],
+			   hw = ((uint32_t)hs[0] << 16) | hs[1];
       for (hs++; hs <= end && hw != nw; )
 	hw = hw << 16 | *++hs;
       return hw == nw ? (void *)(hs - 1) : NULL;
diff --git a/newlib/libc/string/strstr.c b/newlib/libc/string/strstr.c
index 84e4632f1..50dbbec05 100644
--- a/newlib/libc/string/strstr.c
+++ b/newlib/libc/string/strstr.c
@@ -100,7 +100,7 @@ strstr (const char *hs, const char *ne)
 static inline char *
 strstr2 (const unsigned char *hs, const unsigned char *ne)
 {
-  uint32_t h1 = (ne[0] << 16) | ne[1];
+  uint32_t h1 = ((uint32_t)ne[0] << 16) | ne[1];
   uint32_t h2 = 0;
   int c;
   for (c = hs[0]; h1 != h2 && c != 0; c = *++hs)
@@ -111,7 +111,7 @@ strstr2 (const unsigned char *hs, const unsigned char *ne)
 static inline char *
 strstr3 (const unsigned char *hs, const unsigned char *ne)
 {
-  uint32_t h1 = (ne[0] << 24) | (ne[1] << 16) | (ne[2] << 8);
+  uint32_t h1 = ((uint32_t)ne[0] << 24) | ((uint32_t)ne[1] << 16) | (ne[2] << 8);
   uint32_t h2 = 0;
   int c;
   for (c = hs[0]; h1 != h2 && c != 0; c = *++hs)
@@ -122,7 +122,7 @@ strstr3 (const unsigned char *hs, const unsigned char *ne)
 static inline char *
 strstr4 (const unsigned char *hs, const unsigned char *ne)
 {
-  uint32_t h1 = (ne[0] << 24) | (ne[1] << 16) | (ne[2] << 8) | ne[3];
+  uint32_t h1 = ((uint32_t)ne[0] << 24) | ((uint32_t)ne[1] << 16) | (ne[2] << 8) | ne[3];
   uint32_t h2 = 0;
   int c;
   for (c = hs[0]; c != 0 && h1 != h2; c = *++hs)