pref,builder: add support for -macosx-version-min 10.2 and -macosx-version-min 0 (with default of 10.7) (#19626)

Author: spytheman

vlib/v/builder/cc.v

@@ -19,6 +19,8 @@ const (
 
 const c_verror_message_marker = 'VERROR_MESSAGE '
 
+const current_os = os.user_os()
+
 fn (mut v Builder) show_c_compiler_output(res os.Result) {
 	println('======== C Compiler output ========')
 	println(res.output)
@@ -298,7 +300,7 @@ fn (mut v Builder) setup_ccompiler_options(ccompiler string) {
 		ccoptions.args << '-Wl,--export-all'
 		ccoptions.args << '-Wl,--no-entry'
 	}
-	if ccoptions.debug_mode && os.user_os() != 'windows' && v.pref.build_mode != .build_module {
+	if ccoptions.debug_mode && builder.current_os != 'windows' && v.pref.build_mode != .build_module {
 		ccoptions.linker_flags << '-rdynamic' // needed for nicer symbolic backtraces
 	}
 	if v.pref.os == .freebsd {
@@ -320,10 +322,10 @@ fn (mut v Builder) setup_ccompiler_options(ccompiler string) {
 		ccoptions.wargs << '-Wno-write-strings'
 	}
 	if v.pref.is_liveshared || v.pref.is_livemain {
-		if (v.pref.os == .linux || os.user_os() == 'linux') && v.pref.build_mode != .build_module {
+		if v.pref.os == .linux && v.pref.build_mode != .build_module {
 			ccoptions.linker_flags << '-rdynamic'
 		}
-		if v.pref.os == .macos || os.user_os() == 'macos' {
+		if v.pref.os == .macos {
 			ccoptions.args << '-flat_namespace'
 		}
 	}
@@ -349,14 +351,18 @@ fn (mut v Builder) setup_ccompiler_options(ccompiler string) {
 	}
 	// Min macos version is mandatory I think?
 	if v.pref.os == .macos {
-		ccoptions.post_args << '-mmacosx-version-min=10.7'
-	} else if v.pref.os == .ios {
+		if v.pref.macosx_version_min != '0' {
+			ccoptions.post_args << '-mmacosx-version-min=${v.pref.macosx_version_min}'
+		}
+	}
+	if v.pref.os == .ios {
 		if v.pref.is_ios_simulator {
 			ccoptions.post_args << '-miphonesimulator-version-min=10.0'
 		} else {
 			ccoptions.post_args << '-miphoneos-version-min=10.0'
 		}
-	} else if v.pref.os == .windows {
+	}
+	if v.pref.os == .windows {
 		ccoptions.post_args << '-municode'
 	}
 	cflags := v.get_os_cflags()
@@ -382,7 +388,6 @@ fn (mut v Builder) setup_ccompiler_options(ccompiler string) {
 		ccoptions.post_args << '-bt25'
 	}
 	// Without these libs compilation will fail on Linux
-	// || os.user_os() == 'linux'
 	if !v.pref.is_bare && v.pref.build_mode != .build_module
 		&& v.pref.os in [.linux, .freebsd, .openbsd, .netbsd, .dragonfly, .solaris, .haiku] {
 		if v.pref.os in [.freebsd, .netbsd] {
@@ -472,7 +477,7 @@ fn (v &Builder) thirdparty_object_args(ccoptions CcompilerOptions, middle []stri
 }
 
 fn (mut v Builder) setup_output_name() {
-	if !v.pref.is_shared && v.pref.build_mode != .build_module && os.user_os() == 'windows'
+	if !v.pref.is_shared && v.pref.build_mode != .build_module && v.pref.os == .windows
 		&& !v.pref.out_name.ends_with('.exe') {
 		v.pref.out_name += '.exe'
 	}
@@ -860,8 +865,8 @@ fn (mut c Builder) cc_windows_cross() {
 	} else {
 		args << cflags.c_options_after_target()
 	}
-	if os.user_os() !in ['macos', 'linux', 'termux'] {
-		println(os.user_os())
+	if builder.current_os !in ['macos', 'linux', 'termux'] {
+		println(builder.current_os)
 		panic('your platform is not supported yet')
 	}
 	//

vlib/v/help/build/build-c.txt

@@ -155,6 +155,11 @@ see also `v help build`.
       that V will use (`x86_64-w64-mingw32-gcc` for targeting Windows, and
       `clang` for targeting Linux from other operating systems).
 
+   -macosx-version-min 10.7
+      Only relevant on macos. It will be passed as -mmacosx-version-min=10.7 to
+      the C backend compiler clang . It is 10.7 on macos by default. If you
+      pass `-macosx-version-min 0`, then that flag will not be passed at all.
+
    -sanitize
       Pass flags related to sanitization to the C compiler.
 

vlib/v/pref/pref.v

@@ -157,6 +157,7 @@ pub mut:
 	use_cache              bool   // when set, use cached modules to speed up subsequent compilations, at the cost of slower initial ones (while the modules are cached)
 	retry_compilation      bool = true // retry the compilation with another C compiler, if tcc fails.
 	use_os_system_to_run   bool   // when set, use os.system() to run the produced executable, instead of os.new_process; works around segfaults on macos, that may happen when xcode is updated
+	macosx_version_min     string = '10.7' // relevant only for macos and ios targets
 	// TODO Convert this into a []string
 	cflags  string // Additional options which will be passed to the C compiler *before* other options.
 	ldflags string // Additional options which will be passed to the C compiler *after* everything else.
@@ -685,6 +686,11 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 			'-use-os-system-to-run' {
 				res.use_os_system_to_run = true
 			}
+			'-macosx-version-min' {
+				res.macosx_version_min = cmdline.option(current_args, arg, res.macosx_version_min)
+				i++
+				res.build_options << '${arg} ${res.macosx_version_min}'
+			}
 			'-nocache' {
 				res.use_cache = false
 			}
@@ -694,10 +700,12 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 			}
 			'-no-parallel' {
 				res.no_parallel = true
+				res.build_options << arg
 			}
 			'-parallel-cc' {
 				res.parallel_cc = true
 				res.no_parallel = true // TODO: see how to make both work
+				res.build_options << arg
 			}
 			'-native' {
 				res.backend = .native