deprecate skip_children option

Cargo.toml

@@ -57,6 +57,7 @@ annotate-snippets = { version = "0.6", features = ["ansi_term"] }
 structopt = "0.3"
 rustfmt-config_proc_macro = { version = "0.2", path = "config_proc_macro" }
 lazy_static = "1.0.0"
+ansi_term = "0.12"
 
 # A noop dependency that changes in the Rust repository, it's a bit of a hack.
 # See the `src/tools/rustc-workspace-hack/README.md` file in `rust-lang/rust`

Configurations.md

@@ -1881,7 +1881,7 @@ specific version of rustfmt is used in your CI, use this option.
 - **Possible values**: any published version (e.g. `"0.3.8"`)
 - **Stable**: No (tracking issue: #3386)
 
-## `skip_children`
+## `skip_children` (DEPRECATED #3587)
 
 Don't reformat out of line modules
 

src/bin/main.rs

@@ -11,6 +11,8 @@ use std::io::{self, stdout, Read, Write};
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 
+use ansi_term::Colour::Red;
+
 use getopts::{Matches, Options};
 
 use crate::rustfmt::{
@@ -513,6 +515,11 @@ struct GetOptsOptions {
     print_misformatted_file_names: bool,
 }
 
+fn deprecate_skip_children() {
+    let msg = "Option --skip-children is deprecated since it is now the default to not format submodules of given files (#3587)";
+    eprintln!("{}: {}", Red.bold().paint("Deprecation"), msg);
+}
+
 impl GetOptsOptions {
     pub fn from_matches(matches: &Matches) -> Result<GetOptsOptions, FailureError> {
         let mut options = GetOptsOptions::default();
@@ -529,6 +536,7 @@ impl GetOptsOptions {
 
             if options.unstable_features {
                 if matches.opt_present("skip-children") {
+                    deprecate_skip_children();
                     options.skip_children = Some(true);
                 }
                 if matches.opt_present("error-on-unformatted") {
@@ -540,6 +548,7 @@ impl GetOptsOptions {
             } else {
                 let mut unstable_options = vec![];
                 if matches.opt_present("skip-children") {
+                    deprecate_skip_children();
                     unstable_options.push("`--skip-children`");
                 }
                 if matches.opt_present("error-on-unformatted") {

src/config/config_type.rs

@@ -58,6 +58,9 @@ macro_rules! create_config {
 
         use serde::{Deserialize, Serialize};
 
+        // for error messages
+        use ansi_term::Colour::Red;
+
         #[derive(Clone)]
         #[allow(unreachable_pub)]
         pub struct Config {
@@ -137,8 +140,16 @@ macro_rules! create_config {
             }
 
             fn fill_from_parsed_config(mut self, parsed: PartialConfig, dir: &Path) -> Config {
+                let deprecate_skip_children = || {
+                    let msg = "Option skip_children is deprecated since it is now the default to not format submodules of given files (#3587)";
+                    eprintln!("{}: {}", Red.bold().paint("Deprecation"), msg);
+                };
+
             $(
                 if let Some(val) = parsed.$i {
+                    if stringify!($i) == "skip_children" {
+                        deprecate_skip_children()
+                    }
                     if self.$i.3 {
                         self.$i.1 = true;
                         self.$i.2 = val;
@@ -216,6 +227,7 @@ macro_rules! create_config {
                 match key {
                     $(
                         stringify!($i) => {
+                dbg!(stringify!($i));
                             self.$i.1 = true;
                             self.$i.2 = val.parse::<$ty>()
                                 .expect(&format!("Failed to parse override for {} (\"{}\") as a {}",