[DiagnosticVerifier] More accurate wording when printing diagnostics from external sources

Author: owenv

lib/Frontend/DiagnosticVerifier.cpp

@@ -702,7 +702,7 @@ void DiagnosticVerifier::printRemainingDiagnostics() const {
   for (const auto &diag : CapturedDiagnostics) {
     SM.getLLVMSourceMgr().PrintMessage(
         llvm::errs(), diag.getLoc(), diag.getKind(),
-        "diagnostic produced by Clang: " + diag.getMessage(),
+        "diagnostic produced elsewhere: " + diag.getMessage(),
         /*Ranges=*/ {}, diag.getFixIts());
   }
 }

test/Frontend/verify-broken-c-module.swift

@@ -6,6 +6,6 @@
 // RUN: not %target-typecheck-verify-swift -I %S/Inputs/broken-c-module 2>&1 | %FileCheck %s
 
 // CHECK: [[@LINE+3]]:8: error: unexpected error produced: could not build
-// CHECK: note: diagnostic produced by Clang: in file included from <module-includes>
-// CHECK: broken_c.h:2:11: error: diagnostic produced by Clang: expected function body after function declarator
+// CHECK: note: diagnostic produced elsewhere: in file included from <module-includes>
+// CHECK: broken_c.h:2:11: error: diagnostic produced elsewhere: expected function body after function declarator
 import BrokenCModule

test/Frontend/verify.swift

@@ -10,3 +10,7 @@ undefinedFunc()
 
 // CHECK: [[@LINE+1]]:20: error: expected {{{{}} in {{expected}}-{{warning}}
 // expected-warning
+
+// CHECK: [[@LINE+2]]:8: error: unexpected error produced: generic type 'Array' specialized with too many type parameters
+// CHECK: note: diagnostic produced elsewhere: generic type 'Array' declared here
+let x: Array<Int, Int>