LANGUAGE property is not set for source files added with target_sources

When adding a source file via the target_sources function, the LANGUAGE property is not set on the source file.

Incidentally, obtaining the LOCATION property from the source file first seems to result in the LANGUAGE property being correctly set.

Simple reproduction case:

project(test_project)

add_executable(test_exe)
target_sources(test_exe PRIVATE main.c)

# Uncomment this line to make the "LANGUAGE" work
# get_source_file_property(_loc main.c LOCATION)

get_source_file_property(_lang main.c LANGUAGE)
message("Language: ${_lang}") # Set to "NOTFOUND"

It also works if the source file is added using add_executable(test_exe main.c)