file(DOWNLOAD EXPECTED_HASH): better error message when download failed

Source/cmFileCommand.cxx

@@ -2107,6 +2107,14 @@ bool HandleDownloadCommand(std::vector<std::string> const& args,
   // Verify MD5 sum if requested:
   //
   if (hash) {
+    if (res != CURLE_OK) {
+      status.SetError(cmStrCat(
+        "DOWNLOAD cannot compute hash on failed download\n"
+        "  status: [",
+        static_cast<int>(res), ";\"", ::curl_easy_strerror(res), "\"]"));
+      return false;
+    }
+
     std::string actualHash = hash->HashFile(file);
     if (actualHash.empty()) {
       status.SetError("DOWNLOAD cannot compute hash on downloaded file");
@@ -2130,11 +2138,7 @@ bool HandleDownloadCommand(std::vector<std::string> const& args,
                                expectedHash,
                                "]\n"
                                "      actual hash: [",
-                               actualHash,
-                               "]\n"
-                               "           status: [",
-                               static_cast<int>(res), ";\"",
-                               ::curl_easy_strerror(res), "\"]\n"));
+                               actualHash, "]\n"));
       return false;
     }
   }

Tests/RunCMake/file/DOWNLOAD-hash-mismatch-stderr.txt

@@ -4,7 +4,6 @@
     for file: \[.*/Tests/RunCMake/file/DOWNLOAD-hash-mismatch-build/hash-mismatch.txt\]
       expected hash: \[0123456789abcdef0123456789abcdef01234567\]
         actual hash: \[da39a3ee5e6b4b0d3255bfef95601890afd80709\]
-             status: \[0;"No error"\]
 
 Call Stack \(most recent call first\):
   CMakeLists.txt:[0-9]+ \(include\)