[stdlib] fixes warning: result of call to 'initialize(from:)' is unused

[nordicio]

Fixes the following warnings:

+ /usr/local/bin/cmake --build <swift-source>/build/Ninja-RelWithDebInfoAssert/swift-macosx-x86_64 -- -j4 all swift-test-stdlib-macosx-x86_64 swift-benchmark-macosx-x86_64
[966/1642] Generating <swift-source>/swift/macosx/x86_64/Swift.swiftmodule
<swift-source>/swift/stdlib/public/core/StringStorage.swift:81:14: warning: result of call to 'initialize(from:)' is unused
      buffer.initialize(from: UnsafeBufferPointer(start: start, count: count))
             ^         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

and

[1063/1642] Compiling <swift-source>/swift/stdlib/public/core/macosx/x86_64/Swift.o
<swift-source>/swift/stdlib/public/core/StringStorage.swift:81:14: warning: result of call to 'initialize(from:)' is unused
      buffer.initialize(from: UnsafeBufferPointer(start: start, count: count))
             ^         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The bounds check seems alright, so it's just removing the warning.

[harlanhaskins]

@swift-ci please smoke test

cc: @milseman

[Azoy]

cc: @milseman @Catfish-Man can this be rewritten as:

guard maxLength >= count + 1 else { return 0 }
outputPtr.initialize(from: start, count: count)
outputPtr[count] = 0
return 1

?

[Catfish-Man]

I strongly suspect it can! Good catch

[Catfish-Man]

@swift-ci please test

[harlanhaskins]

Thanks for this, @nordicio!