A freestanding expression macro that expands to/contains `#isolation` macro, crashes the compiler when put as a default argument

Description

No response

Reproduction

Implementation

struct SomeMacro1: ExpressionMacro {
    static func expansion(of _: some FreestandingMacroExpansionSyntax, in _: some MacroExpansionContext) throws -> ExprSyntax { "#isolation" }
}

@main
struct TestMacroPlugin: CompilerPlugin {
    let providingMacros: [Macro.Type] = [
        SomeMacro1.self,
    ]
}

Client

@freestanding(expression)
public macro someMacro() -> Any = #externalMacro(module: "TestMacros", type: "SomeMacro1")

@MainActor
func foo() {
    bar()
}

func bar(thing: Any = #someMacro) {
    print(thing)
}

Stack dump

1.	Apple Swift version 6.3.3 (swift-6.3.3-RELEASE)
2.	Compiling with the current language version
3.	While evaluating request ASTLoweringRequest(Lowering AST to SIL for file "/Users/x/Xcode/TestMacro/Sources/Test/Test.swift")
4.	While silgen emitFunction SIL function "@$s4Test3fooyyF".
 for 'foo()' (at /Users/x/Xcode/TestMacro/Sources/Test/Test.swift:10:1)
 #0 0x000000010ddc2598 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x106066598)
 #1 0x000000010ddc0703 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x106064703)
 #2 0x000000010ddc30a6 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1060670a6)
 #3 0x00007ff81673c31d (/usr/lib/system/libsystem_platform.dylib+0x7ff801f0c31d)
 #4 0x0000000000000000
 #5 0x000000010875bf77 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009fff77)
 #6 0x000000010874a891 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009ee891)
 #7 0x000000010875c6f1 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100a006f1)
 #8 0x000000010874a8a1 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009ee8a1)
 #9 0x000000010875c6f1 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100a006f1)
#10 0x000000010874a8a1 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009ee8a1)
#11 0x000000010875374e (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009f774e)
#12 0x000000010874a7dd (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009ee7dd)
#13 0x000000010874084d (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009e484d)
#14 0x00000001086e9f0e (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10098df0e)
#15 0x00000001086d80a1 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10097c0a1)
#16 0x00000001086e84d7 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10098c4d7)
#17 0x00000001086f4e3d (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100998e3d)
#18 0x00000001086f4560 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100998560)
#19 0x00000001086dcde4 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100980de4)
#20 0x00000001086da72e (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10097e72e)
#21 0x000000010874a6c1 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009ee6c1)
#22 0x0000000108740e42 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009e4e42)
#23 0x00000001087e05b9 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100a845b9)
#24 0x00000001087ded65 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100a82d65)
#25 0x00000001087698f3 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100a0d8f3)
#26 0x00000001086c6ff3 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10096aff3)
#27 0x00000001086c7bd2 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10096bbd2)
#28 0x00000001086c54db (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1009694db)
#29 0x00000001086cab73 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10096eb73)
#30 0x00000001086cb1c3 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10096f1c3)
#31 0x00000001087de6e1 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100a826e1)
#32 0x00000001087de5ee (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100a825ee)
#33 0x00000001086cf199 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x100973199)
#34 0x00000001086cb828 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x10096f828)
#35 0x0000000108020751 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1002c4751)
#36 0x00000001080257d7 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1002c97d7)
#37 0x00000001080224e8 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1002c64e8)
#38 0x0000000107d904b1 (/Users/x/Library/Developer/Toolchains/swift-6.3.3-RELEASE.xctoolchain/usr/bin/swift-frontend+0x1000344b1)
#39 0x00007ff81635e530

Expected behavior

It should compile without an issue.

Environment

Apple Swift version 6.3.3 (swift-6.3.3-RELEASE)
Target: x86_64-apple-macosx15.0

Additional information

No response

Reproduce the crash using the freestanding expression macro and default argument shown in the issue, compiling the client in Test.swift with Apple Swift 6.3.3. Trace the ASTLoweringRequest and SIL generation path reported in the stack dump; done means the same example compiles without crashing.