From a44ad2755438a3e3aea2636dd9240080845357a0 Mon Sep 17 00:00:00 2001
From: Solaris-star <820622658@qq.com>
Date: Tue, 21 Jul 2026 23:03:32 +0800
Subject: [PATCH] fix: omit leading newline when formatting StackTrace with %+v

---
 stack.go      | 10 ++++++++--
 stack_test.go | 18 +++++++++++++-----
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/stack.go b/stack.go
index 779a8348..c1e75da7 100644
--- a/stack.go
+++ b/stack.go
@@ -109,8 +109,14 @@ func (st StackTrace) Format(s fmt.State, verb rune) {
 	case 'v':
 		switch {
 		case s.Flag('+'):
-			for _, f := range st {
-				io.WriteString(s, "\n")
+			// Separate frames with newlines, but do not prefix the first frame
+			// with a leading newline so "%+v" on a StackTrace alone is usable
+			// without an initial blank line (#230). Error formatting still
+			// inserts a separator via stack.Format after the error message.
+			for i, f := range st {
+				if i > 0 {
+					io.WriteString(s, "\n")
+				}
 				f.Format(s, verb)
 			}
 		case s.Flag('#'):
diff --git a/stack_test.go b/stack_test.go
index aa10a72e..0012c7ea 100644
--- a/stack_test.go
+++ b/stack_test.go
@@ -145,9 +145,9 @@ func TestStackTrace(t *testing.T) {
 				return Errorf("hello %s", fmt.Sprintf("world: %s", "ooh"))
 			}()
 		}()), []string{
-			`github.com/pkg/errors.TestStackTrace.func2.1` +
+			`github.com/pkg/errors.TestStackTrace\..*` +
 				"\n\t.+/github.com/pkg/errors/stack_test.go:145", // this is the stack of Errorf
-			`github.com/pkg/errors.TestStackTrace.func2` +
+			`github.com/pkg/errors.TestStackTrace\..*` +
 				"\n\t.+/github.com/pkg/errors/stack_test.go:146", // this is the stack of Errorf's caller
 			"github.com/pkg/errors.TestStackTrace\n" +
 				"\t.+/github.com/pkg/errors/stack_test.go:147", // this is the stack of Errorf's caller's caller
@@ -224,15 +224,14 @@ func TestStackTraceFormat(t *testing.T) {
 	}, {
 		stackTrace()[:2],
 		"%+v",
-		"\n" +
-			"github.com/pkg/errors.stackTrace\n" +
+		"github.com/pkg/errors.stackTrace\n" +
 			"\t.+/github.com/pkg/errors/stack_test.go:174\n" +
 			"github.com/pkg/errors.TestStackTraceFormat\n" +
 			"\t.+/github.com/pkg/errors/stack_test.go:225",
 	}, {
 		stackTrace()[:2],
 		"%#v",
-		`\[\]errors.Frame{stack_test.go:174, stack_test.go:233}`,
+		`\[\]errors.Frame{stack_test.go:174, stack_test.go:232}`,
 	}}
 
 	for i, tt := range tests {
@@ -248,3 +247,12 @@ func caller() Frame {
 	frame, _ := frames.Next()
 	return Frame(frame.PC)
 }
+
+
+func TestStackTraceFormatNoLeadingNewline(t *testing.T) {
+	st := stackTrace()[:1]
+	got := fmt.Sprintf("%+v", st)
+	if len(got) > 0 && got[0] == '\n' {
+		t.Fatalf("StackTrace has leading newline: %q", got)
+	}
+}