Looks like a long string will make this happen. Seems the component width needs to be passed into react-input-autosize's placeholderIsMinWidth prop.
I'll be happy to do a PR. What do you think is the best course of action?

+1
Just created a PR for it here https://github.com/JedWatson/react-input-autosize/pull/71. Hopefully it'll get merged.
Just stumbled on this issue and didn't like the option of setting a fixed pixel value as max-width since we're dealing with a fluid layout.
Here's my solution, which allows us to set max-width in percentages, pixel or my personal favorite - calc(), the tricky part was just setting table-layout: fixed:
.Select-control {
table-layout: fixed;
}
.Select-input {
overflow: hidden;
max-width: calc(100% - 20px);
}
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Most helpful comment
Just stumbled on this issue and didn't like the option of setting a fixed pixel value as max-width since we're dealing with a fluid layout.
Here's my solution, which allows us to set
max-widthin percentages, pixel or my personal favorite -calc(), the tricky part was just settingtable-layout: fixed: