Add rustc --drawing to use Unicode line drawing characters for span output

I bet we can find other uses for these sorts of characters in clarifying type
errors, etc.

This is marked as a "stable" flag for consistency with --color. However we
should reconsider both of them as part of #19051. For these features to be
conveniently available with Cargo, we may want to use environment variables or
a config file.

Author: Keegan McAllister

man/rustc.1

@@ -139,6 +139,9 @@ always colorize output;
 .B never
 never colorize output.
 .RE
+.TP
+\fB\-\-drawing\fR
+Use drawing characters in diagnostic output
 
 .SH CODEGEN OPTIONS
 

src/librustc/lint/context.rs

@@ -36,6 +36,7 @@ use util::nodemap::FnvHashMap;
 
 use std::cell::RefCell;
 use std::cmp;
+use std::default;
 use std::mem;
 use syntax::ast_util::{self, IdVisitingOperation};
 use syntax::attr::{self, AttrMetaMethods};
@@ -46,7 +47,6 @@ use rustc_front::hir;
 use rustc_front::util;
 use rustc_front::visit as hir_visit;
 use syntax::visit as ast_visit;
-use syntax::diagnostic;
 
 /// Information about the registered lints.
 ///
@@ -166,7 +166,7 @@ impl LintStore {
                 match (sess, from_plugin) {
                     // We load builtin lints first, so a duplicate is a compiler bug.
                     // Use early_error when handling -W help with no crate.
-                    (None, _) => early_error(diagnostic::ColorConfig::Auto, &msg[..]),
+                    (None, _) => early_error(default::Default::default(), &msg[..]),
                     (Some(sess), false) => sess.bug(&msg[..]),
 
                     // A duplicate name from a plugin is a user error.
@@ -190,7 +190,7 @@ impl LintStore {
             match (sess, from_plugin) {
                 // We load builtin lints first, so a duplicate is a compiler bug.
                 // Use early_error when handling -W help with no crate.
-                (None, _) => early_error(diagnostic::ColorConfig::Auto, &msg[..]),
+                (None, _) => early_error(default::Default::default(), &msg[..]),
                 (Some(sess), false) => sess.bug(&msg[..]),
 
                 // A duplicate name from a plugin is a user error.

src/librustc/session/config.rs

@@ -27,7 +27,8 @@ use metadata::cstore;
 use syntax::ast::{self, IntTy, UintTy};
 use syntax::attr;
 use syntax::attr::AttrMetaMethods;
-use syntax::diagnostic::{ColorConfig, SpanHandler};
+use syntax::diagnostic;
+use syntax::diagnostic::{ColorConfig, EmitterConfig, SpanHandler};
 use syntax::parse;
 use syntax::parse::token::InternedString;
 use syntax::feature_gate::UnstableFeatures;
@@ -37,6 +38,7 @@ use std::collections::HashMap;
 use std::env;
 use std::fmt;
 use std::path::PathBuf;
+use std::default;
 
 use llvm;
 
@@ -106,7 +108,7 @@ pub struct Options {
     pub debugging_opts: DebuggingOptions,
     pub prints: Vec<PrintRequest>,
     pub cg: CodegenOptions,
-    pub color: ColorConfig,
+    pub emit_cfg: diagnostic::EmitterConfig,
     pub show_span: Option<String>,
     pub externs: HashMap<String, Vec<String>>,
     pub crate_name: Option<String>,
@@ -216,7 +218,7 @@ pub fn basic_options() -> Options {
         debugging_opts: basic_debugging_options(),
         prints: Vec::new(),
         cg: basic_codegen_options(),
-        color: ColorConfig::Auto,
+        emit_cfg: default::Default::default(),
         show_span: None,
         externs: HashMap::new(),
         crate_name: None,
@@ -284,7 +286,7 @@ macro_rules! options {
         $struct_name { $($opt: $init),* }
     }
 
-    pub fn $buildfn(matches: &getopts::Matches, color: ColorConfig) -> $struct_name
+    pub fn $buildfn(matches: &getopts::Matches, cfg: EmitterConfig) -> $struct_name
     {
         let mut op = $defaultfn();
         for option in matches.opt_strs($prefix) {
@@ -298,17 +300,17 @@ macro_rules! options {
                 if !setter(&mut op, value) {
                     match (value, opt_type_desc) {
                         (Some(..), None) => {
-                            early_error(color, &format!("{} option `{}` takes no \
+                            early_error(cfg, &format!("{} option `{}` takes no \
                                                          value", $outputname, key))
                         }
                         (None, Some(type_desc)) => {
-                            early_error(color, &format!("{0} option `{1}` requires \
+                            early_error(cfg, &format!("{0} option `{1}` requires \
                                                          {2} ({3} {1}=<value>)",
                                                         $outputname, key,
                                                         type_desc, $prefix))
                         }
                         (Some(value), Some(type_desc)) => {
-                            early_error(color, &format!("incorrect value `{}` for {} \
+                            early_error(cfg, &format!("incorrect value `{}` for {} \
                                                          option `{}` - {} was expected",
                                                         value, $outputname,
                                                         key, type_desc))
@@ -320,7 +322,7 @@ macro_rules! options {
                 break;
             }
             if !found {
-                early_error(color, &format!("unknown {} option: `{}`",
+                early_error(cfg, &format!("unknown {} option: `{}`",
                                             $outputname, key));
             }
         }
@@ -822,6 +824,7 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
             auto   = colorize, if output goes to a tty (default);
             always = always colorize output;
             never  = never colorize output", "auto|always|never"),
+        opt::flag("", "drawing", "Use drawing characters in diagnostic output"),
 
         opt::flagopt_u("", "pretty",
                    "Pretty-print the input instead of compiling;
@@ -853,24 +856,28 @@ pub fn parse_cfgspecs(cfgspecs: Vec<String> ) -> ast::CrateConfig {
 }
 
 pub fn build_session_options(matches: &getopts::Matches) -> Options {
-    let color = match matches.opt_str("color").as_ref().map(|s| &s[..]) {
+    let mut emit_cfg: diagnostic::EmitterConfig = default::Default::default();
+    emit_cfg.color = match matches.opt_str("color").as_ref().map(|s| &s[..]) {
         Some("auto")   => ColorConfig::Auto,
         Some("always") => ColorConfig::Always,
         Some("never")  => ColorConfig::Never,
 
         None => ColorConfig::Auto,
 
         Some(arg) => {
-            early_error(ColorConfig::Auto,
+            early_error(emit_cfg,
                         &format!("argument for --color must be auto, always \
                                   or never (instead was `{}`)",
                                  arg))
         }
     };
+    if matches.opt_present("drawing") {
+        emit_cfg.drawing = true;
+    }
 
     let unparsed_crate_types = matches.opt_strs("crate-type");
     let crate_types = parse_crate_types_from_list(unparsed_crate_types)
-        .unwrap_or_else(|e| early_error(color, &e[..]));
+        .unwrap_or_else(|e| early_error(emit_cfg, &e[..]));
 
     let mut lint_opts = vec!();
     let mut describe_lints = false;
@@ -887,11 +894,11 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 
     let lint_cap = matches.opt_str("cap-lints").map(|cap| {
         lint::Level::from_str(&cap).unwrap_or_else(|| {
-            early_error(color, &format!("unknown lint level: `{}`", cap))
+            early_error(emit_cfg, &format!("unknown lint level: `{}`", cap))
         })
     });
 
-    let debugging_opts = build_debugging_options(matches, color);
+    let debugging_opts = build_debugging_options(matches, emit_cfg);
 
     let parse_only = debugging_opts.parse_only;
     let no_trans = debugging_opts.no_trans;
@@ -916,7 +923,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
                     "link" => OutputType::Exe,
                     "dep-info" => OutputType::DepInfo,
                     part => {
-                        early_error(color, &format!("unknown emission type: `{}`",
+                        early_error(emit_cfg, &format!("unknown emission type: `{}`",
                                                     part))
                     }
                 };
@@ -929,15 +936,15 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         output_types.insert(OutputType::Exe, None);
     }
 
-    let cg = build_codegen_options(matches, color);
+    let cg = build_codegen_options(matches, emit_cfg);
 
     let sysroot_opt = matches.opt_str("sysroot").map(|m| PathBuf::from(&m));
     let target = matches.opt_str("target").unwrap_or(
         host_triple().to_string());
     let opt_level = {
         if matches.opt_present("O") {
             if cg.opt_level.is_some() {
-                early_error(color, "-O and -C opt-level both provided");
+                early_error(emit_cfg, "-O and -C opt-level both provided");
             }
             Default
         } else {
@@ -948,7 +955,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
                 Some(2) => Default,
                 Some(3) => Aggressive,
                 Some(arg) => {
-                    early_error(color, &format!("optimization level needs to be \
+                    early_error(emit_cfg, &format!("optimization level needs to be \
                                                  between 0-3 (instead was `{}`)",
                                                 arg));
                 }
@@ -959,7 +966,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let gc = debugging_opts.gc;
     let debuginfo = if matches.opt_present("g") {
         if cg.debuginfo.is_some() {
-            early_error(color, "-g and -C debuginfo both provided");
+            early_error(emit_cfg, "-g and -C debuginfo both provided");
         }
         FullDebugInfo
     } else {
@@ -968,7 +975,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
             Some(1) => LimitedDebugInfo,
             Some(2) => FullDebugInfo,
             Some(arg) => {
-                early_error(color, &format!("debug info level needs to be between \
+                early_error(emit_cfg, &format!("debug info level needs to be between \
                                              0-2 (instead was `{}`)",
                                             arg));
             }
@@ -977,7 +984,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 
     let mut search_paths = SearchPaths::new();
     for s in &matches.opt_strs("L") {
-        search_paths.add_path(&s[..], color);
+        search_paths.add_path(&s[..], emit_cfg);
     }
 
     let libs = matches.opt_strs("l").into_iter().map(|s| {
@@ -989,7 +996,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
             (Some(name), "framework") => (name, cstore::NativeFramework),
             (Some(name), "static") => (name, cstore::NativeStatic),
             (_, s) => {
-                early_error(color, &format!("unknown library kind `{}`, expected \
+                early_error(emit_cfg, &format!("unknown library kind `{}`, expected \
                                              one of dylib, framework, or static",
                                             s));
             }
@@ -1006,13 +1013,13 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
             "file-names" => PrintRequest::FileNames,
             "sysroot" => PrintRequest::Sysroot,
             req => {
-                early_error(color, &format!("unknown print request `{}`", req))
+                early_error(emit_cfg, &format!("unknown print request `{}`", req))
             }
         }
     }).collect::<Vec<_>>();
 
     if !cg.remark.is_empty() && debuginfo == NoDebugInfo {
-        early_warn(color, "-C remark will not show source locations without \
+        early_warn(emit_cfg, "-C remark will not show source locations without \
                            --debuginfo");
     }
 
@@ -1021,11 +1028,11 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         let mut parts = arg.splitn(2, '=');
         let name = match parts.next() {
             Some(s) => s,
-            None => early_error(color, "--extern value must not be empty"),
+            None => early_error(emit_cfg, "--extern value must not be empty"),
         };
         let location = match parts.next() {
             Some(s) => s,
-            None => early_error(color, "--extern value must be of the format `foo=bar`"),
+            None => early_error(emit_cfg, "--extern value must be of the format `foo=bar`"),
         };
 
         externs.entry(name.to_string()).or_insert(vec![]).push(location.to_string());
@@ -1055,7 +1062,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         debugging_opts: debugging_opts,
         prints: prints,
         cg: cg,
-        color: color,
+        emit_cfg: emit_cfg,
         show_span: None,
         externs: externs,
         crate_name: crate_name,

src/librustc/session/mod.rs

@@ -394,7 +394,7 @@ pub fn build_session(sopts: config::Options,
 
     let codemap = codemap::CodeMap::new();
     let diagnostic_handler =
-        diagnostic::Handler::new(sopts.color, Some(registry), can_print_warnings);
+        diagnostic::Handler::new(sopts.emit_cfg, Some(registry), can_print_warnings);
     let span_diagnostic_handler =
         diagnostic::SpanHandler::new(diagnostic_handler, codemap);
 
@@ -473,13 +473,13 @@ pub fn expect<T, M>(sess: &Session, opt: Option<T>, msg: M) -> T where
     diagnostic::expect(sess.diagnostic(), opt, msg)
 }
 
-pub fn early_error(color: diagnostic::ColorConfig, msg: &str) -> ! {
-    let mut emitter = diagnostic::EmitterWriter::stderr(color, None);
+pub fn early_error(cfg: diagnostic::EmitterConfig, msg: &str) -> ! {
+    let mut emitter = diagnostic::EmitterWriter::stderr(cfg, None);
     emitter.emit(None, msg, None, diagnostic::Fatal);
     panic!(diagnostic::FatalError);
 }
 
-pub fn early_warn(color: diagnostic::ColorConfig, msg: &str) {
-    let mut emitter = diagnostic::EmitterWriter::stderr(color, None);
+pub fn early_warn(cfg: diagnostic::EmitterConfig, msg: &str) {
+    let mut emitter = diagnostic::EmitterWriter::stderr(cfg, None);
     emitter.emit(None, msg, None, diagnostic::Warning);
 }

src/librustc/session/search_paths.rs

@@ -38,7 +38,7 @@ impl SearchPaths {
         SearchPaths { paths: Vec::new() }
     }
 
-    pub fn add_path(&mut self, path: &str, color: diagnostic::ColorConfig) {
+    pub fn add_path(&mut self, path: &str, cfg: diagnostic::EmitterConfig) {
         let (kind, path) = if path.starts_with("native=") {
             (PathKind::Native, &path["native=".len()..])
         } else if path.starts_with("crate=") {
@@ -53,7 +53,7 @@ impl SearchPaths {
             (PathKind::All, path)
         };
         if path.is_empty() {
-            early_error(color, "empty search path given via `-L`");
+            early_error(cfg, "empty search path given via `-L`");
         }
         self.paths.push((kind, PathBuf::from(path)));
     }

src/librustc_back/target/mod.rs

@@ -250,7 +250,7 @@ impl Target {
         // this is 1. ugly, 2. error prone.
 
 
-        let handler = diagnostic::Handler::new(diagnostic::ColorConfig::Auto, None, true);
+        let handler = diagnostic::Handler::new(Default::default(), None, true);
 
         let get_req_field = |name: &str| {
             match obj.find(name)