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[Macros] Termination signal for executable plugin #3164

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[Macros] Termination signal for executable plugin #3164

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4 changes: 4 additions & 0 deletions Sources/SwiftCompilerPluginMessageHandling/StandardIOMessageConnection.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,10 @@ public struct StandardIOMessageConnection: MessageConnection {

// Read the JSON payload.
let count = Int(UInt64(littleEndian: header))
// Empty message is a termination signal.
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Is the compiler explicitly sending a message with header == 0 to indicate that the plugin process should exit?

if count == 0 {
return nil
}
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@rintaro rintaro Oct 10, 2025 •
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FWIW, not returning nil is still safe. try _read(into: data) is no-op, and JSON.decode() would throw an Error, then the caller would exit(1). This change just make it graceful immediate exit(0)

let data = UnsafeMutableRawBufferPointer.allocate(byteCount: count, alignment: 1)
defer { data.deallocate() }
try _read(into: data)
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