check-md: verify code example formatting (vlang#7143)

README.md

@@ -24,7 +24,7 @@
 ## Key Features of V
 
 - Simplicity: the language can be learned in less than an hour
-- Fast compilation: ≈80k loc/s with a Clang backend, 
+- Fast compilation: ≈80k loc/s with a Clang backend,
     ≈1 million loc/s with x64 and tcc backends *(Intel i5-7500, SSD, no optimization)*
 - Easy to develop: V compiles itself in less than a second
 - Performance: as fast as C (V's main backend compiles to human readable C)
@@ -81,7 +81,7 @@ v up
 
 ### C compiler
 
-It's recommended to use Clang or GCC or Visual Studio. 
+It's recommended to use Clang or GCC or Visual Studio.
 If you are doing development, you most likely already have one of those installed.
 
 Otherwise, follow these instructions:
@@ -90,8 +90,8 @@ Otherwise, follow these instructions:
 
 - [Installing a C compiler on Windows](https://github.com/vlang/v/wiki/Installing-a-C-compiler-on-Windows)
 
-However, if none is found when running `make` on Linux or Windows, 
-TCC would be downloaded and set as an alternative C backend. 
+However, if none is found when running `make` on Linux or Windows,
+TCC would be downloaded and set as an alternative C backend.
 It's very lightweight (several MB) so this shouldn't take too long.
 
 ### Symlinking
@@ -227,9 +227,9 @@ https://github.com/vlang/ui
 
 ```v
 fn main() {
-        for i in 0..3 {
-                println('Hello from V.js')
-        }
+	for i in 0 .. 3 {
+		println('Hello from V.js')
+	}
 }
 ```
 

cmd/tools/check-md.v

@@ -102,7 +102,6 @@ fn eline(file_path string, lnumber int, column int, message string) string {
 	return btext('$file_path:${lnumber + 1}:${column + 1}:') + btext(rtext(' error: $message'))
 }
 
-//
 const (
 	default_command = 'compile'
 )
@@ -190,16 +189,23 @@ fn (mut f MDFile) check_examples() (int, int) {
 		vfile := os.join_path(os.temp_dir(), 'check_${fname}_example_${e.sline}__${e.eline}__${uid}.v')
 		mut should_cleanup_vfile := true
 		// eprintln('>>> checking example $vfile ...')
-		vcontent := e.text.join('\n')
+		vcontent := e.text.join('\n') + '\n'
 		os.write_file(vfile, vcontent) or { panic(err) }
 		mut acommands := e.command.split(' ')
+		nofmt := 'nofmt' in acommands
 		for command in acommands {
 			match command {
 				'compile' {
 					res := os.system('"$vexe" -w -Wfatal-errors -o x.c $vfile')
 					os.rm('x.c') or { }
-					if res != 0 {
-						eprintln(eline(f.path, e.sline, 0, 'example failed to compile'))
+					fmt_res := if nofmt { 0 } else { os.system('"$vexe" fmt -verify $vfile') }
+					if res != 0 || fmt_res != 0 {
+						if res != 0 {
+							eprintln(eline(f.path, e.sline, 0, 'example failed to compile'))
+						}
+						if fmt_res != 0 {
+							eprintln(eline(f.path, e.sline, 0, 'example is not formatted'))
+						}
 						eprintln(vcontent)
 						should_cleanup_vfile = false
 						errors++
@@ -209,8 +215,14 @@ fn (mut f MDFile) check_examples() (int, int) {
 				}
 				'live' {
 					res := os.system('"$vexe" -w -Wfatal-errors -live -o x.c $vfile')
-					if res != 0 {
-						eprintln(eline(f.path, e.sline, 0, 'example failed to compile with -live'))
+					fmt_res := if nofmt { 0 } else { os.system('"$vexe" fmt -verify $vfile') }
+					if res != 0 || fmt_res != 0 {
+						if res != 0 {
+							eprintln(eline(f.path, e.sline, 0, 'example failed to compile with -live'))
+						}
+						if fmt_res != 0 {
+							eprintln(eline(f.path, e.sline, 0, 'example is not formatted'))
+						}
 						eprintln(vcontent)
 						should_cleanup_vfile = false
 						errors++
@@ -232,8 +244,14 @@ fn (mut f MDFile) check_examples() (int, int) {
 				}
 				'oksyntax' {
 					res := os.system('"$vexe" -w -Wfatal-errors -check-syntax $vfile')
-					if res != 0 {
-						eprintln(eline(f.path, e.sline, 0, '`oksyntax` example with invalid syntax'))
+					fmt_res := if nofmt { 0 } else { os.system('"$vexe" fmt -verify $vfile') }
+					if res != 0 || fmt_res != 0 {
+						if res != 0 {
+							eprintln(eline(f.path, e.sline, 0, '`oksyntax` example with invalid syntax'))
+						}
+						if fmt_res != 0 {
+							eprintln(eline(f.path, e.sline, 0, '`oksyntax` example is not formatted'))
+						}
 						eprintln(vcontent)
 						should_cleanup_vfile = false
 						errors++
@@ -252,6 +270,7 @@ fn (mut f MDFile) check_examples() (int, int) {
 					}
 					oks++
 				}
+				'nofmt' {}
 				else {
 					eprintln(eline(f.path, e.sline, 0, 'unrecognized command: "$command", use one of: wip/ignore/compile/failcompile/oksyntax/badsyntax'))
 					should_cleanup_vfile = false