auto merge of #14115 : alexcrichton/rust/core-fmt, r=brson

This was a more difficult change than I thought it would be, and it is unfortunately a breaking change rather than a drop-in replacement. Most of the rationale can be found in the third commit.

cc #13851

2 files changed, 2 insertions, 2 deletions

diff --git a/src/libregex/parse.rs b/src/libregex/parse.rs
index d1a01cc974f..a695da9fa16 100644
--- a/src/libregex/parse.rs
+++ b/src/libregex/parse.rs
@@ -37,7 +37,7 @@ pub struct Error {
 
 impl fmt::Show for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f.buf, "Regex syntax error near position {}: {}",
+        write!(f, "Regex syntax error near position {}: {}",
                self.pos, self.msg)
     }
 }
diff --git a/src/libregex/re.rs b/src/libregex/re.rs
index f22889b22a3..899c54d601b 100644
--- a/src/libregex/re.rs
+++ b/src/libregex/re.rs
@@ -117,7 +117,7 @@ pub struct Regex {
 impl fmt::Show for Regex {
     /// Shows the original regular expression.
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f.buf, "{}", self.original)
+        write!(f, "{}", self.original)
     }
 }