[Frontend] Switch to -validate-tbd-against-ir=missing by default.

A validation failure now includes a note about how to turn it off, for when
there's TBD bugs that block someone's work.

Author: huonw

include/swift/AST/DiagnosticsFrontend.def

@@ -194,6 +194,11 @@ ERROR(symbol_in_ir_not_in_tbd,none,
       "symbol '%0' (%1) is in generated IR file, but not in TBD file",
       (StringRef, StringRef))
 
+NOTE(pass_validate_tbd_against_ir_none,none,
+     "please file a bug including this code as a test case, and consider adding "
+     "'-Xfrontend -validate-tbd-against-ir=none' to the Swift compiler options to "
+     "silence this error", ())
+
 ERROR(invalid_conditional_compilation_flag,none,
       "conditional compilation flags must be valid Swift identifiers (rather than '%0')",
       (StringRef))

include/swift/Frontend/FrontendOptions.h

@@ -291,7 +291,7 @@ class FrontendOptions {
   };
 
   /// Compare the symbols in the IR against the TBD file we would generate.
-  TBDValidationMode ValidateTBDAgainstIR = TBDValidationMode::None;
+  TBDValidationMode ValidateTBDAgainstIR = TBDValidationMode::MissingFromTBD;
 
   /// An enum with different modes for automatically crashing at defined times.
   enum class DebugCrashMode {

lib/FrontendTool/FrontendTool.cpp

@@ -974,6 +974,12 @@ static bool performCompile(CompilerInstance &Instance,
       break;
 
     const auto &silOpts = Invocation.getSILOptions();
+
+    // -sil-serialize-all is problematic and not what we intend to do long term,
+    // so we don't try to get the public symbols to line up.
+    if (silOpts.SILSerializeAll)
+      break;
+
     auto hasMultipleIRGenThreads = silOpts.NumThreads > 1;
     bool error;
     if (PrimarySourceFile)

lib/FrontendTool/TBD.cpp

@@ -120,6 +120,12 @@ static bool validateSymbolSet(DiagnosticEngine &diags,
     }
   }
 
+  if (error) {
+    // Inform the user how to silence this error (and request they file a bug)
+    // so they can continue working while us compiler folk fix it properly.
+    diags.diagnose(SourceLoc(), diag::pass_validate_tbd_against_ir_none);
+  }
+
   return error;
 }
 

test/Migrator/member.swift

@@ -1,5 +1,5 @@
 // REQUIRES: objc_interop
-// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -F %S/mock-sdk -api-diff-data-file %S/Inputs/API.json -emit-migrated-file-path %t/member.swift.result -emit-remap-file-path %t/member.swift.remap -o /dev/null
+// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -F %S/mock-sdk -api-diff-data-file %S/Inputs/API.json -emit-migrated-file-path %t/member.swift.result -emit-remap-file-path %t/member.swift.remap -o /dev/null -validate-tbd-against-ir=none
 // RUN: diff -u %S/member.swift.expected %t/member.swift.result
 
 import Bar

test/Migrator/member.swift.expected

@@ -1,5 +1,5 @@
 // REQUIRES: objc_interop
-// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -F %S/mock-sdk -api-diff-data-file %S/Inputs/API.json -emit-migrated-file-path %t/member.swift.result -emit-remap-file-path %t/member.swift.remap -o /dev/null
+// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -F %S/mock-sdk -api-diff-data-file %S/Inputs/API.json -emit-migrated-file-path %t/member.swift.result -emit-remap-file-path %t/member.swift.remap -o /dev/null -validate-tbd-against-ir=none
 // RUN: diff -u %S/member.swift.expected %t/member.swift.result
 
 import Bar

test/Migrator/rename.swift

@@ -1,5 +1,5 @@
 // REQUIRES: objc_interop
-// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -F %S/mock-sdk -api-diff-data-file %S/Inputs/API.json -emit-migrated-file-path %t/rename.swift.result -emit-remap-file-path %t/rename.swift.remap -o /dev/null
+// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -F %S/mock-sdk -api-diff-data-file %S/Inputs/API.json -emit-migrated-file-path %t/rename.swift.result -emit-remap-file-path %t/rename.swift.remap -o /dev/null -validate-tbd-against-ir=none
 // RUN: diff -u %S/rename.swift.expected %t/rename.swift.result
 
 import Bar

test/Migrator/rename.swift.expected

@@ -1,5 +1,5 @@
 // REQUIRES: objc_interop
-// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -F %S/mock-sdk -api-diff-data-file %S/Inputs/API.json -emit-migrated-file-path %t/rename.swift.result -emit-remap-file-path %t/rename.swift.remap -o /dev/null
+// RUN: %empty-directory(%t) && %target-swift-frontend -c -update-code -primary-file %s -F %S/mock-sdk -api-diff-data-file %S/Inputs/API.json -emit-migrated-file-path %t/rename.swift.result -emit-remap-file-path %t/rename.swift.remap -o /dev/null -validate-tbd-against-ir=none
 // RUN: diff -u %S/rename.swift.expected %t/rename.swift.result
 
 import Bar