How can I find function Fcopy_sequence in the Emacs C source code?
copy-sequence is written in
C and is contained within the source code file
fns.c. If the source code files are available, they should be in a directory that matches the variable
find-function-C-source-directory (which can be adjusted as needed).
The decision whether to include source code files is generally made at the time Emacs is built from source, but they can be added in the desired location after Emacs is built and the above-mentioned variable can be adjusted accordingly.
See also the variable
source-directory. Keep in mind, however, that the function
find-function-C-source looks for source code files in the path set by the variable
find-function-C-source-directory (rather than the variable