From: Ian Lance Taylor <iant@golang.org>
Date: Tue, 5 Oct 2021 18:41:40 +0000 (-0700)
Subject: text/template: only unwrap final and/or value
X-Git-Tag: go1.18beta1~1037
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=8444a545e3d38c2e470df5035ef4b5a9365aaefc;p=gostls13.git

text/template: only unwrap final and/or value

In the last CL I missed the fact that except for the final value the
code already unwraps the argument.

For #31103

Change-Id: Ic9099aeb50c6b3322fc14a90ac8026c1d8cb1698
Reviewed-on: https://go-review.googlesource.com/c/go/+/354091
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
---

diff --git a/src/text/template/exec.go b/src/text/template/exec.go
index 9a4c9e29dd..9ae6fdc3cc 100644
--- a/src/text/template/exec.go
+++ b/src/text/template/exec.go
@@ -728,13 +728,21 @@ func (s *state) evalCall(dot, fun reflect.Value, isBuiltin bool, node parse.Node
 		for _, arg := range args {
 			v = s.evalArg(dot, argType, arg).Interface().(reflect.Value)
 			if truth(v) == (name == "or") {
-				return unwrap(v)
+				// This value was already unwrapped
+				// by the .Interface().(reflect.Value).
+				return v
 			}
 		}
 		if final != missingVal {
-			v = s.validateType(final, argType)
+			// The last argument to and/or is coming from
+			// the pipeline. We didn't short circuit on an earlier
+			// argument, so we are going to return this one.
+			// We don't have to evaluate final, but we do
+			// have to check its type. Then, since we are
+			// going to return it, we have to unwrap it.
+			v = unwrap(s.validateType(final, argType))
 		}
-		return unwrap(v)
+		return v
 	}
 
 	// Build the arg list.
diff --git a/src/text/template/exec_test.go b/src/text/template/exec_test.go
index 1a839a641b..9c0772945e 100644
--- a/src/text/template/exec_test.go
+++ b/src/text/template/exec_test.go
@@ -489,6 +489,8 @@ var execTests = []execTest{
 	{"and pipe-false", "{{0 | and 1}}", "0", nil, true},
 	{"or pipe-true", "{{1 | or 0}}", "1", nil, true},
 	{"or pipe-false", "{{0 | or 0}}", "0", nil, true},
+	{"and undef", "{{and 1 .Unknown}}", "<no value>", nil, true},
+	{"or undef", "{{or 0 .Unknown}}", "<no value>", nil, true},
 	{"boolean if", "{{if and true 1 `hi`}}TRUE{{else}}FALSE{{end}}", "TRUE", tVal, true},
 	{"boolean if not", "{{if and true 1 `hi` | not}}TRUE{{else}}FALSE{{end}}", "FALSE", nil, true},
 	{"boolean if pipe", "{{if true | not | and 1}}TRUE{{else}}FALSE{{end}}", "FALSE", nil, true},