Get rid of signed/unsigned comparaison in _sre.c

Fix compilation warnings on Windows (Visual C++) like: "_sre.c(3121): warning
C4018: '>' : signed/unsigned mismatch".

_validate_outer() ensures that groups >= 0, so _validate_inner() can cast
groups to size_t.

Modules/_sre.c

@@ -795,7 +795,7 @@ entrance:
     if (ctx->pattern[0] == SRE_OP_INFO) {
         /* optimization info block */
         /* <INFO> <1=skip> <2=flags> <3=min> ... */
-        if (ctx->pattern[3] && (end - ctx->ptr)/state->charsize < ctx->pattern[3]) {
+        if (ctx->pattern[3] && (Py_uintptr_t)(end - ctx->ptr)/state->charsize < ctx->pattern[3]) {
             TRACE(("reject (got %d chars, need %d)\n",
                    (end - ctx->ptr)/state->charsize, ctx->pattern[3]));
             RETURN_FAILURE;
@@ -2762,7 +2762,7 @@ _compile(PyObject* self_, PyObject* args)
         skip = *code;                                   \
         VTRACE(("%lu (skip to %p)\n",                   \
                (unsigned long)skip, code+skip));        \
-        if (skip-adj > end-code)                        \
+        if (skip-adj > (Py_uintptr_t)(end - code))      \
             FAIL;                                       \
         code++;                                         \
     } while (0)
@@ -2795,7 +2795,7 @@ _validate_charset(SRE_CODE *code, SRE_CODE *end)
 
         case SRE_OP_CHARSET:
             offset = 32/sizeof(SRE_CODE); /* 32-byte bitmap */
-            if (offset > end-code)
+            if (offset > (Py_uintptr_t)(end - code))
                 FAIL;
             code += offset;
             break;
@@ -2803,7 +2803,7 @@ _validate_charset(SRE_CODE *code, SRE_CODE *end)
         case SRE_OP_BIGCHARSET:
             GET_ARG; /* Number of blocks */
             offset = 256/sizeof(SRE_CODE); /* 256-byte table */
-            if (offset > end-code)
+            if (offset > (Py_uintptr_t)(end - code))
                 FAIL;
             /* Make sure that each byte points to a valid block */
             for (i = 0; i < 256; i++) {
@@ -2812,7 +2812,7 @@ _validate_charset(SRE_CODE *code, SRE_CODE *end)
             }
             code += offset;
             offset = arg * 32/sizeof(SRE_CODE); /* 32-byte bitmap times arg */
-            if (offset > end-code)
+            if (offset > (Py_uintptr_t)(end - code))
                 FAIL;
             code += offset;
             break;
@@ -2875,7 +2875,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups)
                sre_match() code is robust even if they don't, and the worst
                you can get is nonsensical match results. */
             GET_ARG;
-            if (arg > 2*groups+1) {
+            if (arg > 2 * (size_t)groups + 1) {
                 VTRACE(("arg=%d, groups=%d\n", (int)arg, (int)groups));
                 FAIL;
             }
@@ -2963,11 +2963,11 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups)
                     GET_ARG; prefix_len = arg;
                     GET_ARG;
                     /* Here comes the prefix string */
-                    if (prefix_len > newcode-code)
+                    if (prefix_len > (Py_uintptr_t)(newcode - code))
                         FAIL;
                     code += prefix_len;
                     /* And here comes the overlap table */
-                    if (prefix_len > newcode-code)
+                    if (prefix_len > (Py_uintptr_t)(newcode - code))
                         FAIL;
                     /* Each overlap value should be < prefix_len */
                     for (i = 0; i < prefix_len; i++) {
@@ -3058,7 +3058,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups)
         case SRE_OP_GROUPREF:
         case SRE_OP_GROUPREF_IGNORE:
             GET_ARG;
-            if (arg >= groups)
+            if (arg >= (size_t)groups)
                 FAIL;
             break;
 
@@ -3067,7 +3067,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups)
                'group' is either an integer group number or a group name,
                'then' and 'else' are sub-regexes, and 'else' is optional. */
             GET_ARG;
-            if (arg >= groups)
+            if (arg >= (size_t)groups)
                 FAIL;
             GET_SKIP_ADJ(1);
             code--; /* The skip is relative to the first arg! */
@@ -3096,7 +3096,7 @@ _validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups)
                to allow arbitrary jumps anywhere in the code; so we just look
                for a JUMP opcode preceding our skip target.
             */
-            if (skip >= 3 && skip-3 < end-code &&
+            if (skip >= 3 && skip-3 < (Py_uintptr_t)(end - code) &&
                 code[skip-3] == SRE_OP_JUMP)
             {
                 VTRACE(("both then and else parts present\n"));