Fix warning flags filter complexity

Author: DmT021

Sources/Build/BuildDescription/ClangModuleBuildDescription.swift

@@ -363,21 +363,18 @@ public final class ClangModuleBuildDescription {
 
         // suppress warnings if the package is remote
         if self.package.isRemote {
-            args += ["-w"]
             // `-w` (suppress warnings) and the other warning control flags are mutually exclusive
-            for index in args.indices.reversed() {
-                let arg = args[index]
-                if arg.starts(with: "-W"), arg.count > 2 {
-                    // we consider the following flags:
-                    // -Wxxxx
-                    // -Wno-xxxx
-                    // -Werror
-                    // -Werror=xxxx
-                    // -Wno-error
-                    // -Wno-error=xxxx
-                    args.remove(at: index)
-                }
+            args = args.filter { arg in
+                // we consider the following flags:
+                // -Wxxxx
+                // -Wno-xxxx
+                // -Werror
+                // -Werror=xxxx
+                // -Wno-error
+                // -Wno-error=xxxx
+                arg.count <= 2 || !arg.starts(with: "-W")
             }
+            args += ["-w"]
         }
 
         return args

Sources/Build/BuildDescription/SwiftModuleBuildDescription.swift

@@ -621,23 +621,27 @@ public final class SwiftModuleBuildDescription {
 
         // suppress warnings if the package is remote
         if self.package.isRemote {
-            args += ["-suppress-warnings"]
             // suppress-warnings and the other warning control flags are mutually exclusive
-            for index in args.indices.reversed() {
-                let arg = args[index]
+            var removeNextArg = false
+            args = args.filter { arg in
+                if removeNextArg {
+                    removeNextArg = false
+                    return false
+                }
                 switch arg {
                 case "-warnings-as-errors", "-no-warnings-as-errors":
-                    args.remove(at: index)
+                    return false
                 case "-Wwarning", "-Werror":
-                    guard args.indices.contains(index + 1) else {
-                        throw InternalError("Unexpected '\(arg)' at the end of args")
-                    }
-                    args.remove(at: index + 1)
-                    args.remove(at: index)
+                    removeNextArg = true
+                    return false
                 default:
-                    break
+                    return true
                 }
             }
+            guard !removeNextArg else {
+                throw InternalError("Unexpected '-Wwarning' or '-Werror' at the end of args")
+            }
+            args += ["-suppress-warnings"]
         }
 
         // Pass `-user-module-version` for versioned packages that aren't pre-releases.