parser: recognize additions with named file headers

src/parser.cpp

@@ -658,6 +658,8 @@ bool Parser::parse_patch_header(Patch& patch, PatchHeaderInfo& header_info, int
                 patch.operation = Operation::Delete;
             else if (hunk.old_file_range.start_line == 0)
                 patch.operation = Operation::Add;
+        } else if (hunk.old_file_range.start_line == 0) {
+            patch.operation = Operation::Add;
         }
     }
 

src/patch.cpp

@@ -513,13 +513,15 @@ int process_patch(const Options& options)
         if (options.verbose || file_to_patch.empty())
             parser.print_header_info(info, out);
 
-        if (file_to_patch.empty())
+        if (file_to_patch.empty() && !options.force && !options.batch)
             file_to_patch = prompt_for_filepath(out);
 
         if (file_to_patch.empty()) {
             if (should_parse_body)
                 parser.parse_patch_body(patch);
 
+            if (options.force || options.batch)
+                out << "No file to patch.  ";
             out << "Skipping patch.\n";
             inform_hunks_failed(out, "ignored", patch.hunks, patch.hunks.size());
             out << '\n';

tests/test_basic.cpp

@@ -492,6 +492,74 @@ PATCH_TEST(add_file)
 )");
 }
 
+PATCH_TEST(add_file_without_dev_null_header)
+{
+    {
+        Patch::File file("diff.patch", std::ios_base::out);
+
+        file << R"(--- add
++++ add
+@@ -0,0 +1,3 @@
++int main()
++{
++}
+)";
+    }
+
+    EXPECT_FALSE(Patch::filesystem::exists("add"));
+
+    Process process(patch_path, { patch_path, "-i", "diff.patch", nullptr });
+
+    EXPECT_EQ(process.stdout_data(), "patching file add\n");
+    EXPECT_EQ(process.stderr_data(), "");
+    EXPECT_EQ(process.return_code(), 0);
+    EXPECT_FILE_EQ("add", R"(int main()
+{
+}
+)");
+}
+
+static void file_not_found_does_not_prompt(const char* patch_path, const char* option)
+{
+    {
+        Patch::File file("diff.patch", std::ios_base::out);
+
+        file << R"(--- a	2023-01-03 11:23:35.634966282 +1300
++++ b	2023-01-03 11:23:41.598960625 +1300
+@@ -1,3 +1,3 @@
+ 1
+-2
++b
+ 3
+)";
+    }
+
+    Process process(patch_path, { patch_path, "-i", "diff.patch", option, nullptr });
+
+    EXPECT_EQ(process.stdout_data(), R"(can't find file to patch at input line 3
+Perhaps you should have used the -p or --strip option?
+The text leading up to this was:
+--------------------------
+|--- a	2023-01-03 11:23:35.634966282 +1300
+|+++ b	2023-01-03 11:23:41.598960625 +1300
+--------------------------
+No file to patch.  Skipping patch.
+1 out of 1 hunk ignored
+)");
+    EXPECT_EQ(process.stderr_data(), "");
+    EXPECT_EQ(process.return_code(), 1);
+}
+
+PATCH_TEST(file_not_found_force_does_not_prompt)
+{
+    file_not_found_does_not_prompt(patch_path, "--force");
+}
+
+PATCH_TEST(file_not_found_batch_does_not_prompt)
+{
+    file_not_found_does_not_prompt(patch_path, "--batch");
+}
+
 PATCH_TEST(add_file_using_basename)
 {
     {