v.pref, v.builder: support `-no-rsp` (pass C options directly to the C compiler backend, without writing response files)

cmd/v/help/build-c.txt

@@ -228,6 +228,15 @@ see also `v help build`.
       Write all C flags into `file.txt`, one flag per line.
       If `file.txt` is `-`, then write the flags to stdout, one flag per line.
 
+   -no-rsp
+      By default, V passes all C compiler options to the backend C compiler
+      in so called "response files" (https://gcc.gnu.org/wiki/Response_Files).
+      This works in most cases, since it works around command line length
+      limitations on older systems (and windows), but some C compilers
+      (older versions of tcc for example) do not support them at all. When
+      you use -no-rsp, V will pass the C compiler options directly to the C
+      compiler, on the command line, without writing an .rsp file first.
+
    -assert aborts
       Call abort() after an assertion failure. Debuggers usually
       install signal handlers for SIGABRT, so your program will stop and you

vlib/v/builder/cc.v

@@ -148,14 +148,11 @@ fn (mut v Builder) rebuild_cached_module(vexe string, imp_path string) string {
 
 fn (mut v Builder) show_cc(cmd string, response_file string, response_file_content string) {
 	if v.pref.is_verbose || v.pref.show_cc {
-		println('')
-		println('=====================')
 		println('> C compiler cmd: $cmd')
-		if v.pref.show_cc {
-			println('> C compiler response file $response_file:')
+		if v.pref.show_cc && !v.pref.no_rsp {
+			println('> C compiler response file "$response_file":')
 			println(response_file_content)
 		}
-		println('=====================')
 	}
 }
 
@@ -610,16 +607,23 @@ fn (mut v Builder) cc() {
 		all_args := v.all_args(v.ccoptions)
 		v.dump_c_options(all_args)
 		str_args := all_args.join(' ')
-		// write args to response file
-		response_file := '${v.out_name_c}.rsp'
-		response_file_content := str_args.replace('\\', '\\\\')
+		mut cmd := '$ccompiler $str_args'
+		mut response_file := ''
+		mut response_file_content := str_args
+		if !v.pref.no_rsp {
+			response_file = '${v.out_name_c}.rsp'
+			response_file_content = str_args.replace('\\', '\\\\')
+			cmd = '$ccompiler "@$response_file"'
 			os.write_file(response_file, response_file_content) or {
-			verror('Unable to write response file "$response_file"')
+				verror('Unable to write to C response file "$response_file"')
+			}
 		}
 		if !v.ccoptions.debug_mode {
 			v.pref.cleanup_files << v.out_name_c
+			if !v.pref.no_rsp {
 				v.pref.cleanup_files << response_file
 			}
+		}
 		$if windows {
 			if v.ccoptions.is_cc_tcc {
 				def_name := v.pref.out_name[0..v.pref.out_name.len - 4]
@@ -628,7 +632,6 @@ fn (mut v Builder) cc() {
 		}
 		//
 		os.chdir(vdir)
-		cmd := '$ccompiler "@$response_file"'
 		tried_compilation_commands << cmd
 		v.show_cc(cmd, response_file, response_file_content)
 		// Run

vlib/v/pref/pref.v

@@ -172,6 +172,7 @@ pub mut:
 	warns_are_errors    bool        // -W, like C's "-Werror", treat *every* warning is an error
 	fatal_errors        bool        // unconditionally exit after the first error with exit(1)
 	reuse_tmpc          bool        // do not use random names for .tmp.c and .tmp.c.rsp files, and do not remove them
+	no_rsp              bool        // when true, pass C backend options directly on the CLI (do not use `.rsp` files for them, some older C compilers do not support them)
 	use_color           ColorOutput // whether the warnings/errors should use ANSI color escapes.
 	is_parallel         bool
 	error_limit         int
@@ -474,6 +475,9 @@ pub fn parse_args(known_external_commands []string, args []string) (&Preferences
 			'-W' {
 				res.warns_are_errors = true
 			}
+			'-no-rsp' {
+				res.no_rsp = true
+			}
 			'-keepc' {
 				res.reuse_tmpc = true
 			}