parser: skip comp_if when building for a different compiler

vlib/v/fmt/fmt_keep_test.v

@@ -45,7 +45,8 @@ fn test_fmt() {
 		}
 		table := table.new_table()
 		file_ast := parser.parse_file(ipath, table, .parse_comments, &pref.Preferences{
-				is_fmt: true
+				is_fmt: true,
+				ccompiler: 'gcc'
 			}, &ast.Scope{
 				parent: 0
 		})

vlib/v/parser/comptime.v

@@ -13,6 +13,7 @@ import vweb.tmpl
 const (
 	supported_platforms = ['windows', 'mac', 'macos', 'darwin', 'linux', 'freebsd', 'openbsd',
 		'netbsd', 'dragonfly', 'android', 'js', 'solaris', 'haiku', 'linux_or_macos']
+	supported_ccompilers = ['tinyc', 'clang', 'mingw', 'msvc', 'gcc']
 )
 
 fn (mut p Parser) resolve_vroot(flag string) string {
@@ -154,15 +155,25 @@ fn (mut p Parser) comp_if() ast.Stmt {
 	}
 	val := p.check_name()
 	mut stmts := []ast.Stmt{}
-	mut skip_os := false
+	mut skip := false
+
 	if val in supported_platforms {
 		os := os_from_string(val)
-		// `$if os {` for a different target, skip everything inside
+		if (!is_not && os != p.pref.os) || (is_not && os == p.pref.os) {
+			skip = true
+		}
+	} else if val in supported_ccompilers {
+		cc := cc_from_string(val)
+		user_cc := cc_from_string(p.pref.ccompiler)
+		if (!is_not && cc != user_cc) || (is_not && cc == user_cc) {
+			skip = true
+		}
+	}
+
+	// `$if os {` or `$if compiler {` for a different target, skip everything inside
 	// to avoid compilation errors (like including <windows.h> or calling WinAPI fns
 	// on non-Windows systems)
-		if !p.pref.is_fmt && ((!is_not && os != p.pref.os) || (is_not && os == p.pref.os)) &&
-			!p.pref.output_cross_c {
-			skip_os = true
+	if !p.pref.is_fmt && !p.pref.output_cross_c && skip {
 		p.check(.lcbr)
 		// p.warn('skipping $if $val os=$os p.pref.os=$p.pref.os')
 		mut stack := 1
@@ -185,14 +196,14 @@ fn (mut p Parser) comp_if() ast.Stmt {
 			}
 			p.next()
 		}
-		}
-	}
+	} else { skip = false }
+
 	mut is_opt := false
 	if p.tok.kind == .question {
 		p.next()
 		is_opt = true
 	}
-	if !skip_os {
+	if !skip {
 		stmts = p.parse_block()
 	}
 	mut node := ast.CompIf{
@@ -269,6 +280,17 @@ fn os_from_string(os string) pref.OS {
 	return .linux
 }
 
+// Helper function to convert string names to CC enum
+pub fn cc_from_string(cc_str string) pref.CompilerType {
+	cc := cc_str.replace('\\', '/').split('/').last().all_before('.')
+	if 'tcc'   in cc { return .tinyc }
+	if 'tinyc' in cc { return .tinyc }
+	if 'clang' in cc { return .clang }
+	if 'mingw' in cc { return .mingw }
+	if 'msvc'  in cc { return .msvc  }
+	return .gcc
+}
+
 // `app.$action()` (`action` is a string)
 // `typ` is `App` in this example
 // fn (mut p Parser) comptime_method_call(typ table.Type) ast.ComptimeCall {

vlib/v/pref/pref.v

@@ -32,6 +32,14 @@ pub enum Backend {
 	x64          // The x64 backend
 }
 
+pub enum CompilerType {
+	tinyc
+	clang
+	mingw
+	msvc
+	gcc
+}
+
 const (
 	list_of_flags_with_param = [
 		'o'