From 3c638f2892471b55ded3982d2639e5c62f00d506 Mon Sep 17 00:00:00 2001
From: Luuk van Dijk <lvd@golang.org>
Date: Wed, 14 Dec 2011 08:22:36 +0100
Subject: [PATCH] gc: Use %#F in error messages instead of %F.

Fixes #2520

R=rsc
CC=golang-dev
https://golang.org/cl/5482056
---
 src/cmd/gc/fmt.c         | 10 +++++++---
 test/fixedbugs/bug383.go | 13 +++++++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)
 create mode 100644 test/fixedbugs/bug383.go

diff --git a/src/cmd/gc/fmt.c b/src/cmd/gc/fmt.c
index 7c50b51e449..23b1808291c 100644
--- a/src/cmd/gc/fmt.c
+++ b/src/cmd/gc/fmt.c
@@ -371,9 +371,13 @@ Vconv(Fmt *fp)
 			return fmtprint(fp, "'\\U%08llux'", x);
 		return fmtprint(fp, "('\\x00' + %B)", v->u.xval);
 	case CTFLT:
-		return fmtprint(fp, "%F", v->u.fval);
-	case CTCPLX:  // ? 1234i ->  (0p+0+617p+1)
-		return fmtprint(fp, "(%F+%F)", &v->u.cval->real, &v->u.cval->imag);
+		if((fp->flags & FmtSharp) || fmtmode == FExp)
+			return fmtprint(fp, "%F", v->u.fval);
+		return fmtprint(fp, "%#F", v->u.fval);
+	case CTCPLX:
+		if((fp->flags & FmtSharp) || fmtmode == FExp)
+			return fmtprint(fp, "(%F+%F)", &v->u.cval->real, &v->u.cval->imag);
+		return fmtprint(fp, "(%#F + %#Fi)", &v->u.cval->real, &v->u.cval->imag);
 	case CTSTR:
 		return fmtprint(fp, "\"%Z\"", v->u.sval);
 	case CTBOOL:
diff --git a/test/fixedbugs/bug383.go b/test/fixedbugs/bug383.go
new file mode 100644
index 00000000000..9dccff590e5
--- /dev/null
+++ b/test/fixedbugs/bug383.go
@@ -0,0 +1,13 @@
+// errchk $G $D/$F.go
+
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Issue 2520
+
+package main
+func main() {
+	if 2e9 { }      // ERROR "2e.09"
+	if 3.14+1i { }  // ERROR "3.14 . 1i"
+}
\ No newline at end of file