clang-tidy: avoid assigments in if expressions

Also enable check in clang-tidy.

Cherry-picked from #20794

Closes #21256

.clang-tidy.yml

@@ -13,6 +13,7 @@ Checks:
   - -clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling
   - -clang-diagnostic-nullability-extension
   - bugprone-assert-side-effect
+  - bugprone-assignment-in-if-condition
   - bugprone-chained-comparison
   - bugprone-dynamic-static-initializers
   - bugprone-macro-parentheses

lib/vtls/gtls.c

@@ -203,10 +203,15 @@ static gnutls_datum_t load_file(const char *file)
   f = curlx_fopen(file, "rb");
   if(!f)
     return loaded_file;
-  if(fseek(f, 0, SEEK_END) != 0 ||
+  if(fseek(f, 0, SEEK_END) != 0)
-     (filelen = ftell(f)) < 0 ||
+    goto out;
-     fseek(f, 0, SEEK_SET) != 0 ||
+  filelen = ftell(f);
-     !(ptr = curlx_malloc((size_t)filelen)))
+  if(filelen < 0)
+    goto out;
+  if(fseek(f, 0, SEEK_SET) != 0)
+    goto out;
+  ptr = curlx_malloc((size_t)filelen);
+  if(!ptr)
     goto out;
   if(fread(ptr, 1, (size_t)filelen, f) < (size_t)filelen) {
     curlx_free(ptr);

lib/vtls/x509asn1.c

@@ -160,7 +160,9 @@ static const char *getASN1Element_(struct Curl_asn1Element *elem,
   b = (unsigned char)*beg++;
   if(!(b & 0x80))
     len = b;
-  else if(!(b &= 0x7F)) {
+  else {
+    b &= 0x7F;
+    if(!b) {
       /* Unspecified length. Since we have all the data, we can determine the
          effective length by skipping element until an end element is found. */
       if(!elem->constructed)
@@ -187,6 +189,7 @@ static const char *getASN1Element_(struct Curl_asn1Element *elem,
         len = (len << 8) | (unsigned char) *beg++;
       } while(--b);
     }
+  }
   if(len > (size_t)(end - beg))
     return NULL;  /* Element data does not fit in source. */
   elem->beg = beg;