FL0007

Avoid $ inside interpolated strings

JavaScript template literals use ${variable} inside the string to interpolate a variable. C# interpolated strings use $"...{variable}...".

Because of the similarity, programmers who use both languages may mistakenly write $"...${variable}...", which "works", but adds an extra dollar sign into the content of the string.

This analyzer prohibits the use of $ at the end of an interpolated string segment (which might be immediately before a variable).

var widgets = $"${key} is ${value}"; // BAD
var widgets = $"{key} is {value}"; // GOOD

var price = $"${amount:f2}"; // disallowed
var price = $"{amount:C}"; //workaround: use formatting to insert a currency symbol