fixing a leak in a copper pipe

Solder may fill the leak, but what caused it? I'd rather cut the bad section out and put a coupling in place. If corroded, replace the line.

They do sell "pipe patches" which are rubber lined metal clamps with tightening screws which can be snugged down over a small leak in a pipe

- if there's room, like it's not right next to a fitting.

But, like another poster has already told you, if the pipe corroded through from the inside, chances are any "patch" you use will at best be a temporary fix, corrosion rarely attacks at just one place.

HTH,

Jeff

I once improvised a patch for a pinhole leak in hard drawn copper tubing by using a hose clamp and a tire patch. It held for several years until I had enough other jobs lined up to get a plumber in to replace the damaged piece of tubing.