compiledb returns nothing when compiling headers with `-x` switch

[sleeptightAnsiC]

Let's say, I want to compile a header-only library. In this case the file extension would be something like *.h *.hpp *.hh , and in order to compile those I need to pass -x <lang> argument to the compiler (e.g. gcc -x c or g++ -x c++). Not doing so could trigger the compilation of pre-compiled-header, adding -x treats them as regular translation units.

So this seems like a valid use case. However, compiledb does not seem to recognize this pattern:

$ git clone https://github.com/nothings/stb.git
$ cd stb
$ echo "cc -x c -c ./stb_image.h -DSTB_IMAGE_IMPLEMENTATION" | compiledb --output -
[]

Notice that after changing the file name extension, the issue will disappear:

$ cp stb_image.h stb_image.c
$ echo "cc -x c -c ./stb_image.c -DSTB_IMAGE_IMPLEMENTATION" | compiledb --output -
[                                                                                                                                                                                                                                                              
 {                                                                                                                                                                                                                                                             
  "directory": "/tmp/stb",                                                                                                                                                                                                                                     
  "arguments": [                                                                                                                                                                                                                                               
   "cc",                                                                                                                                                                                                                                                       
   "-x",                                                                                                                                                                                                                                                       
   "c",                                                                                                                                                                                                                                                        
   "-c",                                                                                                                                                                                                                                                       
   "./stb_image.c",                                                                                                                                                                                                                                            
   "-DSTB_IMAGE_IMPLEMENTATION"                                                                                                                                                                                                                                
  ],                                                                                                                                                                                                                                                           
  "file": "./stb_image.c"                                                                                                                                                                                                                                      
 }                                                                                                                                                                                                                                                             
] 

Tested on version 0.10.7-3 installed from AUR (should be up-to-date with git master branch)

$ python --version
Python 3.13.7
$ uname -a
Linux MAL200424 6.16.3-arch1-1 #1 SMP PREEMPT_DYNAMIC Sat, 23 Aug 2025 15:32:49 +0000 x86_64 GNU/Linux
$ cc --version
cc (GCC) 15.2.1 20250813

[sleeptightAnsiC]

After taking a look at the source tree, it seem there is a code path that checks for -x argument, here:

compiledb/compiledb/compiler.py

Lines 51 to 52 in 2550745

	if arg == "-x" and arg_idx < len(arguments) - 1:
	return arguments[arg_idx + 1]

Not sure why it doesn't work in this case.

EDIT: ahhh... it only looks for files with very few extensions:

compiledb/compiledb/parser.py

Line 31 in 2550745

file_regex = re.compile(r"^.+\.c$|^.+\.cc$|^.+\.cpp$|^.+\.cxx$|^.+\.s$", re.IGNORECASE)