closes bpo-39605: Fix some casts to not cast away const. (GH-18453)

gcc -Wcast-qual turns up a number of instances of casting away constness of pointers. Some of these can be safely modified, by either:

Adding the const to the type cast, as in:

-    return _PyUnicode_FromUCS1((unsigned char*)s, size);
+    return _PyUnicode_FromUCS1((const unsigned char*)s, size);

or, Removing the cast entirely, because it's not necessary (but probably was at one time), as in:

-    PyDTrace_FUNCTION_ENTRY((char *)filename, (char *)funcname, lineno);
+    PyDTrace_FUNCTION_ENTRY(filename, funcname, lineno);

These changes will not change code, but they will make it much easier to check for errors in consts
(cherry picked from commit e6be9b59a911626d6597fe148c32f0342bd2bd24)

Co-authored-by: Andy Lester <andy@petdance.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/Python/marshal.c b/Python/marshal.c
index c6a06e8c239..d3fee32380b 100644
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -734,7 +734,7 @@ r_byte(RFILE *p)
     else {
         const char *ptr = r_string(1, p);
         if (ptr != NULL)
-            c = *(unsigned char *) ptr;
+            c = *(const unsigned char *) ptr;
     }
     return c;
 }