all: add support for `-os wasm32` (needs clang-12 installed for now) (#13094)

vlib/v/builder/cc.v

@@ -290,11 +290,19 @@ fn (mut v Builder) setup_ccompiler_options(ccompiler string) {
 			ccoptions.args << '-fPIC' // -Wl,-z,defs'
 		}
 	}
-	if v.pref.is_bare {
+	if v.pref.is_bare && v.pref.os != .wasm32 {
 		ccoptions.args << '-fno-stack-protector'
 		ccoptions.args << '-ffreestanding'
 		ccoptions.linker_flags << '-static'
 		ccoptions.linker_flags << '-nostdlib'
+	} else if v.pref.os == .wasm32 {
+		ccoptions.args << '--no-standard-libraries'
+		ccoptions.args << '-target wasm32-unknown-unknown'
+		ccoptions.args << '-static'
+		ccoptions.args << '-nostdlib'
+		ccoptions.args << '-ffreestanding'
+		ccoptions.args << '-Wl,--export-all'
+		ccoptions.args << '-Wl,--no-entry'
 	}
 	if ccoptions.debug_mode && os.user_os() != 'windows' && v.pref.build_mode != .build_module {
 		ccoptions.linker_flags << '-rdynamic' // needed for nicer symbolic backtraces
@@ -525,6 +533,8 @@ pub fn (mut v Builder) cc() {
 				'-arch armv7 -arch armv7s -arch arm64'
 			}
 			ccompiler = 'xcrun --sdk iphoneos clang -isysroot $isysroot $arch'
+		} else if v.pref.os == .wasm32 {
+			ccompiler = 'clang-12'
 		}
 		v.setup_ccompiler_options(ccompiler)
 		v.build_thirdparty_obj_files()

vlib/v/gen/c/cgen.v

@@ -624,6 +624,12 @@ pub fn (mut g Gen) init() {
 		g.cheaders.writeln(g.pref.custom_prelude)
 	} else if !g.pref.no_preludes {
 		g.cheaders.writeln('// Generated by the V compiler')
+		if g.pref.os == .wasm32 {
+			g.cheaders.writeln('#define VWASM 1')
+			// Include <stdint.h> instead of <inttypes.h> for WASM target
+			g.cheaders.writeln('#include <stdint.h>')
+			g.cheaders.writeln('#include <stddef.h>')
+		} else {
 			tcc_undef_has_include := '
 	#if defined(__TINYC__) && defined(__has_include)
 	// tcc does not support has_include properly yet, turn it off completely
@@ -638,6 +644,7 @@ pub fn (mut g Gen) init() {
 				g.cheaders.writeln(get_guarded_include_text('<inttypes.h>', 'The C compiler can not find <inttypes.h>. Please install build-essentials')) // int64_t etc
 				g.cheaders.writeln(get_guarded_include_text('<stddef.h>', 'The C compiler can not find <stddef.h>. Please install build-essentials')) // size_t, ptrdiff_t
 			}
+		}
 		g.cheaders.writeln(c_builtin_types)
 		if g.pref.is_bare {
 			g.cheaders.writeln(c_bare_headers)
@@ -5588,7 +5595,7 @@ fn (mut g Gen) write_init_function() {
 	// ___argv is declared as voidptr here, because that unifies the windows/unix logic
 	g.writeln('void _vinit(int ___argc, voidptr ___argv) {')
 
-	if 'no_segfault_handler' !in g.pref.compile_defines {
+	if 'no_segfault_handler' !in g.pref.compile_defines || g.pref.os == .wasm32 {
 		// 11 is SIGSEGV. It is hardcoded here, to avoid FreeBSD compilation errors for trivial examples.
 		g.writeln('#if __STDC_HOSTED__ == 1\n\tsignal(11, v_segmentation_fault_handler);\n#endif')
 	}

vlib/v/gen/c/cheaders.v

@@ -753,7 +753,7 @@ static inline void _wymum(uint64_t *A, uint64_t *B){
 	#else
 	*A=_wyrot(hl)^hh; *B=_wyrot(lh)^ll;
 	#endif
-#elif defined(__SIZEOF_INT128__)
+#elif defined(__SIZEOF_INT128__) && !defined(VWASM)
 	__uint128_t r=*A; r*=*B;
 	#if(WYHASH_CONDOM>1)
 	*A^=(uint64_t)r; *B^=(uint64_t)(r>>64);

vlib/v/pref/default.v

@@ -134,9 +134,12 @@ pub fn (mut p Preferences) fill_with_defaults() {
 		// eprintln('-usecache and -shared flags are not compatible')
 		p.use_cache = false
 	}
-	if p.bare_builtin_dir == '' {
+	if p.bare_builtin_dir == '' && p.os == .wasm32 {
+		p.bare_builtin_dir = os.join_path(p.vroot, 'vlib', 'builtin', 'wasm_bare')
+	} else if p.bare_builtin_dir == '' {
 		p.bare_builtin_dir = os.join_path(p.vroot, 'vlib', 'builtin', 'linux_bare')
 	}
+
 	$if prealloc {
 		if !p.no_parallel {
 			eprintln('disabling parallel cgen, since V was built with -prealloc')

vlib/v/pref/os.v

@@ -21,6 +21,9 @@ pub enum OS {
 	serenity
 	vinix
 	haiku
+	wasm32
+	wasm32_emscripten
+	wasm32_wasi
 	raw
 	all
 }
@@ -46,6 +49,9 @@ pub fn os_from_string(os_str string) ?OS {
 		'haiku' { return .haiku }
 		'raw' { return .raw }
 		'nix' { return .linux }
+		'wasm32' { return .wasm32 }
+		'wasm32-wasi' { return .wasm32_wasi }
+		'wasm32-emscripten' { return .wasm32_emscripten }
 		'' { return ._auto }
 		else { return error('bad OS $os_str') }
 	}
@@ -70,6 +76,9 @@ pub fn (o OS) str() string {
 		.serenity { return 'SerenityOS' }
 		.vinix { return 'Vinix' }
 		.haiku { return 'Haiku' }
+		.wasm32 { return 'WebAssembly' }
+		.wasm32_emscripten { return 'WebAssembly(Emscripten)' }
+		.wasm32_wasi { return 'WebAssembly(WASI)' }
 		.raw { return 'Raw' }
 		.all { return 'all' }
 	}

vlib/v/pref/pref.v

@@ -537,6 +537,9 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 					eprintln('unknown operating system target `$target_os`')
 					exit(1)
 				}
+				if target_os_kind == .wasm32 {
+					res.is_bare = true
+				}
 				res.os = target_os_kind
 				res.build_options << '$arg $target_os'
 			}