tools: add a v should-compile-all examples/*.v examples/gg/ tool, to simplify CIs of V modules.

cmd/tools/vshould-compile-all.v

@@ -0,0 +1,45 @@
+import os
+
+fn main() {
+	mut files := []string{}
+	args := os.args#[2..]
+	for a in args {
+		if os.is_file(a) {
+			files << a
+			continue
+		}
+		if os.is_dir(a) {
+			files << os.walk_ext(a, '.v')
+			continue
+		}
+	}
+	files.sort()
+	if files.len == 0 {
+		println('0 .v files found.\n')
+		println('Usage:')
+		println('  v should-compile-all examples/ some/deep/file.v another/')
+		println('... will try to compile all .v files found in the given folders and files, one by one.')
+		println('If every single one of them compiles, the command will exit with an error code of 0.')
+		println('If *any* of them *fail* to compile, the command will exit with an error code of 1.')
+		println('')
+		println('Note: this command is intended to be used in CI pipelines for v modules, like this:')
+		println(' cd module/ ; v should-compile-all examples/ \n')
+		exit(1)
+	}
+	mut failed_commands := []string{}
+	for idx, example in files {
+		cmd := '${os.quoted_path(@VEXE)} ${os.quoted_path(example)}'
+		println('> compiling ${idx + 1:4}/${files.len:-4}: $cmd')
+		if 0 != os.system(cmd) {
+			failed_commands << cmd
+		}
+	}
+	if failed_commands.len > 0 {
+		for idx, fcmd in failed_commands {
+			eprintln('>>> FAILED command ${idx + 1:4}/${failed_commands.len:-4}: $fcmd')
+		}
+		println('Summary: ${failed_commands.len:4}/${files.len:-4} file(s) failed to compile.')
+		exit(1)
+	}
+	println('Summary: all $files.len file(s) compiled successfully.')
+}

cmd/v/v.v

@@ -32,6 +32,7 @@ const (
 		'self',
 		'setup-freetype',
 		'shader',
+		'should-compile-all',
 		'symlink',
 		'scan',
 		'test',