Ehire Adrianza, in the best shape of his life and hitting dingers off Clayton Kershaw, is going on the disabled list after fracturing his left foot with a foul ball. Kelby Tomlinson will be the primary backup at shortstop for now, and he's starting against the Dodgers on Friday night.
The Giants could call up an outfielder like Mac Williamson or Jarrett Parker to fill the roster spot, though they might prefer the flexibility of another backup infielder. There aren't any other shortstops on the 40-man roster, but they can clear a spot by transferring Ian Gardeck (Tommy John surgery) to the 60-day DL, which would allow them to call up ... well, all sorts of folks.
Edit: It's Mac Williamson. But take a ride on the hypothetical roller coaster with me.
Hak-Ju Lee would seem to be the logical choice, as the lefty-hitting shortstop is off to a hot start in Sacramento and has two-plus years of Triple-A experience. He's also a career .231/.318/.325 hitter at Triple-A, though, so if the Giants are looking for offense, they might turn to Christian Arroyo. He's still just 20 and they don't need to add him to the 40-man roster soon, but he might be the best hitter available.
Other options might include Rando Moreno, Grant Green, or bringing up Andrew Susac to be the third catcher. Ramiro Pena has extensive experience at short, and there's also a chance that they could just go with a player whose primary function would be to pinch-hit, like Williamson, Parker, or Conor Gillaspie.
I'd go with Lee, but nobody asks me anything around here. Considering that Gregor Blanco is starting against Kershaw on purpose on Friday night, maybe Williamson wouldn't be a bad idea.
Best wishes to Adrianza on a speedy recovery. He was really off to a nice start this season.