Merge pull request #28550 from drodriguez/windows-avoid-stdout-stderr-mix

[test] Redirect stderr to a different file to avoid mixing with stdout.

Author: compnerd

test/Frontend/ast-dump.swift

@@ -4,9 +4,9 @@
 // RUN: echo 'public func main() {a(); b()}' >%t/main.swift
 
 // Test printing to stdout
-// RUN: %target-swift-frontend -dump-ast -primary-file %t/a.swift %t/b.swift %t/main.swift -module-name main -o - 2>&1 | %FileCheck -check-prefix A-AST %s
-// RUN: %target-swift-frontend -dump-ast %t/a.swift -primary-file %t/b.swift %t/main.swift -module-name main -o - 2>&1 | %FileCheck -check-prefix B-AST %s
-// RUN: %target-swift-frontend -dump-ast %t/a.swift %t/b.swift -primary-file %t/main.swift -module-name main -o - 2>&1 | %FileCheck -check-prefix MAIN-AST %s
+// RUN: %target-swift-frontend -dump-ast -primary-file %t/a.swift %t/b.swift %t/main.swift -module-name main -o - 2>%t/a.swift.stderr | %FileCheck -check-prefix A-AST %s
+// RUN: %target-swift-frontend -dump-ast %t/a.swift -primary-file %t/b.swift %t/main.swift -module-name main -o - 2>%t/b.swift.stderr | %FileCheck -check-prefix B-AST %s
+// RUN: %target-swift-frontend -dump-ast %t/a.swift %t/b.swift -primary-file %t/main.swift -module-name main -o - 2>%t/main.swift.stderr | %FileCheck -check-prefix MAIN-AST %s
 
 // Test printing to files
 // RUN: %target-swift-frontend -dump-ast -primary-file %t/a.swift %t/b.swift %t/main.swift -module-name main -o %t/a.ast