Work around a diagnostic using CommandLine.arguments on older toolchains. (#2622)

grynspan · web-flow · commit 6c459f272857 · 2024-04-24T15:06:41.000-07:00
`CommandLine.arguments` is declared read/write in older toolchains and this
causes an error diagnostic when it's used in Swift 6 mode. This PR uses
`CommandLine.argc` and `CommandLine.unsafeArgv` directly instead so the
diagnostic does not occur.
diff --git a/Sources/SwiftCompilerPlugin/CompilerPlugin.swift b/Sources/SwiftCompilerPlugin/CompilerPlugin.swift
@@ -92,7 +92,12 @@ extension CompilerPlugin {
       }
     }
 
-    let pluginPath = CommandLine.arguments.first ?? "<unknown>"
+    let pluginPath: String
+    if CommandLine.argc > 0, let cPluginPath = CommandLine.unsafeArgv[0] {
+      pluginPath = String(cString: cPluginPath)
+    } else {
+      pluginPath = "<unknown>"
+    }
     throw CompilerPluginError(
       message:
         "macro implementation type '\(moduleName).\(typeName)' could not be found in executable plugin '\(pluginPath)'"

Original file line number	Diff line number	Diff line change
`@@ -92,7 +92,12 @@ extension CompilerPlugin {`
`92`	`92`	`}`
`93`	`93`	`}`
`94`	`94`
`95`		`- let pluginPath = CommandLine.arguments.first ?? "<unknown>"`
	`95`	`+ let pluginPath: String`
	`96`	`+ if CommandLine.argc > 0, let cPluginPath = CommandLine.unsafeArgv[0] {`
	`97`	`+ pluginPath = String(cString: cPluginPath)`
	`98`	`+ } else {`
	`99`	`+ pluginPath = "<unknown>"`
	`100`	`+ }`
`96`	`101`	`throw CompilerPluginError(`
`97`	`102`	`message:`
`98`	`103`	`"macro implementation type '\(moduleName).\(typeName)' could not be found in executable plugin '\(pluginPath)'"`