From e613c8b492495aeb5f75f94a0cdcf252573a345f Mon Sep 17 00:00:00 2001
From: mcarton <cartonmartin+git@gmail.com>
Date: Fri, 1 Jul 2016 18:38:50 +0200
Subject: [PATCH] Introduce `multispan_sugg`

---
 clippy_lints/src/lib.rs       |  1 +
 clippy_lints/src/utils/mod.rs | 22 +++++++++++++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 41a61feab53..6bdfbe98b5b 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -38,6 +38,7 @@
 
 extern crate rustc_serialize;
 
+extern crate rustc_errors;
 extern crate rustc_plugin;
 extern crate rustc_const_eval;
 extern crate rustc_const_math;
diff --git a/clippy_lints/src/utils/mod.rs b/clippy_lints/src/utils/mod.rs
index df9d09ed010..3e0f0db6ac1 100644
--- a/clippy_lints/src/utils/mod.rs
+++ b/clippy_lints/src/utils/mod.rs
@@ -9,12 +9,13 @@
 use rustc::traits;
 use rustc::ty::subst::Subst;
 use rustc::ty;
+use rustc_errors;
 use std::borrow::Cow;
 use std::env;
 use std::mem;
 use std::str::FromStr;
 use syntax::ast::{self, LitKind};
-use syntax::codemap::{ExpnInfo, Span, ExpnFormat};
+use syntax::codemap::{ExpnFormat, ExpnInfo, MultiSpan, Span};
 use syntax::errors::DiagnosticBuilder;
 use syntax::ptr::P;
 
@@ -490,6 +491,25 @@ pub fn span_lint_and_then<'a, T: LintContext, F>(cx: &'a T, lint: &'static Lint,
     }
 }
 
+/// Create a suggestion made from several `span → replacement`.
+///
+/// Note: in the JSON format (used by `compiletest_rs`), the help message will appear once per
+/// replacement. In human-readable format though, it only appears once before the whole suggestion.
+pub fn multispan_sugg(db: &mut DiagnosticBuilder, help_msg: String, sugg: &[(Span, &str)]) {
+    let sugg = rustc_errors::RenderSpan::Suggestion(rustc_errors::CodeSuggestion {
+        msp: MultiSpan::from_spans(sugg.iter().map(|&(span, _)| span).collect()),
+        substitutes: sugg.iter().map(|&(_, subs)| subs.to_owned()).collect(),
+    });
+
+    let sub = rustc_errors::SubDiagnostic {
+        level: rustc_errors::Level::Help,
+        message: help_msg,
+        span: MultiSpan::new(),
+        render_span: Some(sugg),
+    };
+    db.children.push(sub);
+}
+
 /// Return the base type for references and raw pointers.
 pub fn walk_ptrs_ty(ty: ty::Ty) -> ty::Ty {
     match ty.sty {
-- 
2.44.0