Added tests for correct highlighting of strings with shared prefix

Author: faculerena

compiler/rustc_errors/src/lib.rs

@@ -318,7 +318,7 @@ fn as_substr<'a>(original: &'a str, suggestion: &'a str) -> Option<(usize, &'a s
     {
         return Some((0, prefix, original.len()));
     }
-    
+
     let common_prefix = original
         .chars()
         .zip(suggestion.chars())

tests/ui/imports/same-prefix-unresolved-import-148070.rs

@@ -0,0 +1,5 @@
+// https://github.com/rust-lang/rust/issues/148070
+#![no_main]
+use stat; //~ ERROR unresolved import `stat`
+use str; //~ ERROR unresolved import `str`
+use sync; //~ ERROR unresolved import `sync`

tests/ui/imports/same-prefix-unresolved-import-148070.stderr

@@ -0,0 +1,43 @@
+error[E0432]: unresolved import `stat`
+  --> $DIR/same-prefix-unresolved-import-148070.rs:3:5
+   |
+LL | use stat;
+   |     ^^^^ no `stat` in the root
+   |
+help: consider importing this struct instead
+   |
+LL | use std::os::linux::raw::stat;
+   |     +++++++++++++++++++++
+
+error[E0432]: unresolved import `str`
+  --> $DIR/same-prefix-unresolved-import-148070.rs:4:5
+   |
+LL | use str;
+   |     ^^^ no `str` in the root
+   |
+help: a similar name exists in the module
+   |
+LL - use str;
+LL + use std;
+   |
+help: consider importing one of these items instead
+   |
+LL | use std::primitive::str;
+   |     ++++++++++++++++
+LL | use std::str;
+   |     +++++
+
+error[E0432]: unresolved import `sync`
+  --> $DIR/same-prefix-unresolved-import-148070.rs:5:5
+   |
+LL | use sync;
+   |     ^^^^ no `sync` in the root
+   |
+help: consider importing this module instead
+   |
+LL | use std::sync;
+   |     +++++
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0432`.