use @response_files.txt for linking in ninja

Response files are a means to work around the limited command line length
particularly on Windows. Instead of listing all to-be-linked object files
on the command line, ninja will write them into a "response file" and
address that in the command using the @something.txt syntax.

configure.py

@@ -209,6 +209,7 @@ def __init__(self, source_paths, options, modules):
         self.handbook_output_dir = os.path.join(self.doc_output_dir, 'handbook')
         self.doc_output_dir_doxygen = os.path.join(self.doc_output_dir, 'doxygen') if options.with_doxygen else None
         self.doc_module_info = os.path.join(self.build_dir, 'module_info') if options.with_doxygen else None
+        self.response_file_dir = os.path.join(self.build_dir, 'response_files')
 
         # We split the header include paths into 'public', 'internal' and 'external'
         # to allow for better control over what is exposed to each compilation unit.
@@ -272,6 +273,7 @@ def build_dirs(self):
             self.internal_include_dir,
             self.external_include_dir,
             self.handbook_output_dir,
+            self.response_file_dir
         ]
         if self.doc_output_dir_doxygen:
             out += [self.doc_output_dir_doxygen, self.doc_module_info]
@@ -1938,6 +1940,7 @@ def _build_info(sources, objects, target_type):
 
             if target_type in ['fuzzer', 'examples']:
                 exe_basename = os.path.basename(obj_file).replace('.' + osinfo.obj_suffix, osinfo.program_suffix)
+                info['exe_basename'] = exe_basename
 
                 if target_type == 'fuzzer':
                     info['exe'] = os.path.join(build_paths.fuzzer_output_dir, exe_basename)
@@ -2210,6 +2213,7 @@ def test_exe_extra_ldflags():
         'doc_output_dir': build_paths.doc_output_dir,
         'handbook_output_dir': build_paths.handbook_output_dir,
         'doc_output_dir_doxygen': build_paths.doc_output_dir_doxygen,
+        'response_file_dir': build_paths.response_file_dir,
 
         'os': options.os,
         'arch': options.arch,

src/build-data/ninja.in

@@ -57,15 +57,19 @@ default all
 %{if build_static_lib}
 
 rule link_static
-  command = %{ar_command} %{ar_options} %{ar_output_to}$out $in
+  rspfile = %{response_file_dir}/static.txt
+  rspfile_content = $in
+  command = %{ar_command} %{ar_options} %{ar_output_to}$out @%{response_file_dir}/static.txt
 
 build %{out_dir}/%{static_lib_name}: link_static %{join lib_objs}
 
 %{endif}
 %{if build_shared_lib}
 
 rule link_shared
-  command = %{lib_link_cmd} ${ABI_FLAGS} ${LDFLAGS} $in ${LIB_LINKS_TO} %{output_to_exe}$out
+  rspfile = %{response_file_dir}/shared.txt
+  rspfile_content = $in
+  command = %{lib_link_cmd} ${ABI_FLAGS} ${LDFLAGS} @%{response_file_dir}/shared.txt ${LIB_LINKS_TO} %{output_to_exe}$out
 
 build %{out_dir}/%{shared_lib_name}: link_shared %{join lib_objs}
 %{endif}
@@ -80,15 +84,19 @@ build %{out_dir}/%{soname_patch}: symlink %{out_dir}/%{shared_lib_name}
 %{endif}
 
 rule link_cli
-  command = ${EXE_LINK_CMD} ${ABI_FLAGS} $in ${BUILD_DIR_LINK_PATH} ${LANG_EXE_FLAGS} ${LDFLAGS} ${EXE_LINKS_TO} %{output_to_exe}$out
+  rspfile = %{response_file_dir}/cli_${cli_name}.txt
+  rspfile_content = $in
+  command = ${EXE_LINK_CMD} ${ABI_FLAGS} @%{response_file_dir}/cli_${cli_name}.txt ${BUILD_DIR_LINK_PATH} ${LANG_EXE_FLAGS} ${LDFLAGS} ${EXE_LINKS_TO} %{output_to_exe}$out
 
 rule link_tests
-  command = ${EXE_LINK_CMD} ${ABI_FLAGS} $in ${BUILD_DIR_LINK_PATH} ${LANG_EXE_FLAGS} ${LDFLAGS} %{test_exe_extra_ldflags} ${EXE_LINKS_TO} %{output_to_exe}$out
-
+  rspfile = %{response_file_dir}/tests.txt
+  rspfile_content = $in
+  command = ${EXE_LINK_CMD} ${ABI_FLAGS} @%{response_file_dir}/tests.txt ${BUILD_DIR_LINK_PATH} ${LANG_EXE_FLAGS} ${LDFLAGS} %{test_exe_extra_ldflags} ${EXE_LINKS_TO} %{output_to_exe}$out
 
 # Executable targets
 
 build %{cli_exe}: link_cli %{join cli_objs} | libs
+  cli_name = cli
 
 build %{test_exe}: link_tests %{join test_objs} | libs
 
@@ -121,6 +129,7 @@ build examples: phony | %{example_bin}
 %{if build_bogo_shim}
 
 build botan_bogo_shim: link_cli bogo_shim_object | libs
+  cli_name = bogo
 
 # BoGo shim
 build %{out_dir}/bogo_shim_object: compile_exe %{bogo_shim_src}
@@ -130,6 +139,7 @@ build %{out_dir}/bogo_shim_object: compile_exe %{bogo_shim_src}
 %{if build_ct_selftest}
 
 build botan_ct_selftest: link_cli ct_selftest_object | libs
+  cli_name = ct_selftest
 
 build %{out_dir}/ct_selftest_object: compile_exe %{ct_selftest_src}
 
@@ -214,4 +224,5 @@ build %{exe}: link_fuzzer %{obj} | libs
 %{for examples_build_info}
 build %{obj}: compile_example_exe %{src}
 build %{exe}: link_cli %{obj} | libs
+  cli_name = example_%{exe_basename}
 %{endfor}