Fix lifetime diagnotics on an empty tuple.

atrick · atrick · commit bcc4a78c4273 · 2025-06-23T00:19:21.000-07:00
Consider an empty tuple to be a value introducer rather than a forwarding
instruction.

Fixes rdar://153978086 ([nonescapable] compiler crash with dependency on an
expression)
diff --git a/SwiftCompilerSources/Sources/Optimizer/Utilities/ForwardingUtils.swift b/SwiftCompilerSources/Sources/Optimizer/Utilities/ForwardingUtils.swift
@@ -118,7 +118,7 @@ extension ForwardingUseDefWalker {
   }
   mutating func walkUpDefault(forwarded value: Value, _ path: PathContext)
     -> WalkResult {
-    if let inst = value.forwardingInstruction {
+    if let inst = value.forwardingInstruction, !inst.forwardedOperands.isEmpty {
       return walkUp(instruction: inst, path)
     }
     if let phi = Phi(value) {

Original file line number	Diff line number	Diff line change
`@@ -118,7 +118,7 @@ extension ForwardingUseDefWalker {`
`118`	`118`	`}`
`119`	`119`	`mutating func walkUpDefault(forwarded value: Value, _ path: PathContext)`
`120`	`120`	`-> WalkResult {`
`121`		`- if let inst = value.forwardingInstruction {`
	`121`	`+ if let inst = value.forwardingInstruction, !inst.forwardedOperands.isEmpty {`
`122`	`122`	`return walkUp(instruction: inst, path)`
`123`	`123`	`}`
`124`	`124`	`if let phi = Phi(value) {`