Fix inconsistent interpolation with empty mappings and tuples

google · Nov 20, 2023 · 44d276b · 44d276b
1 parent 556fd59
commit 44d276b
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Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/starlark/eval.go b/starlark/eval.go
@@ -1659,8 +1659,10 @@ func interpolate(format string, x Value) (Value, error) {
 		index++
 	}
 
-	if index < nargs {
-		return nil, fmt.Errorf("too many arguments for format string")
+	if _, ok := x.(Mapping); !ok {
+		if index < nargs {
+			return nil, fmt.Errorf("too many arguments for format string")
+		}
 	}
 
 	return String(buf.String()), nil

diff --git a/starlark/testdata/string.star b/starlark/testdata/string.star
@@ -172,7 +172,9 @@ assert.eq(gothash, wanthash)
 # TODO(adonovan): ordered comparisons
 
 # string % tuple formatting
+assert.eq("A" % (), "A")
 assert.eq("A %d %x Z" % (123, 456), "A 123 1c8 Z")
+assert.eq("A" % {'unused': 123}, "A")
 assert.eq("A %(foo)d %(bar)s Z" % {"foo": 123, "bar": "hi"}, "A 123 hi Z")
 assert.eq("%s %r" % ("hi", "hi"), 'hi "hi"')  # TODO(adonovan): use ''-quotation
 assert.eq("%%d %d" % 1, "%d 1")