[sourcekit] Send notification if compiler argument parsing fails in editor.open

Since we will not reach `createAST` where we would normally send the
notification, send one from `getInvocation` when it fails.

rdar://39225180

Author: benlangmuir

test/SourceKit/CompileNotifications/arg-parsing.swift

@@ -1,4 +1,6 @@
 // RUN: not %sourcekitd-test -req=track-compiles == -req=complete %s -offset=0 -- %s -no-such-arg | %FileCheck %s -check-prefix=ARG_PARSE_1
+// RUN: %sourcekitd-test -req=track-compiles == -req=sema %s -print-raw-response -- %s -no-such-arg | %FileCheck %s -check-prefix=ARG_PARSE_1
+// RUN: %sourcekitd-test -req=track-compiles == -req=cursor -offset=0 %s -- %s -no-such-arg | %FileCheck %s -check-prefix=ARG_PARSE_1
 // ARG_PARSE_1: {
 // ARG_PARSE_1:  key.notification: source.notification.compile-will-start
 // ARG_PARSE_1:  key.compileid: [[CID1:".*"]]
@@ -17,3 +19,23 @@
 // ARG_PARSE_1: }
 // ARG_PARSE_1-NOT: compile-will-start
 // ARG_PARSE_1-NOT: compile-did-finish
+
+// RUN: not %sourcekitd-test -req=track-compiles == -req=complete %s -offset=0 | %FileCheck %s -check-prefix=ARG_PARSE_2
+// RUN: %sourcekitd-test -req=track-compiles == -req=sema %s -print-raw-response | %FileCheck %s -check-prefix=ARG_PARSE_2
+// ARG_PARSE_2: {
+// ARG_PARSE_2:  key.notification: source.notification.compile-will-start
+// ARG_PARSE_2:  key.compileid: [[CID1:".*"]]
+// ARG_PARSE_2: }
+// ARG_PARSE_2: {
+// ARG_PARSE_2:   key.notification: source.notification.compile-did-finish
+// ARG_PARSE_2:   key.diagnostics: [
+// ARG_PARSE_2:     {
+// ARG_PARSE_2:       key.filepath: "<unknown>",
+// ARG_PARSE_2:       key.severity: source.diagnostic.severity.error,
+// ARG_PARSE_2:       key.description: "no input files"
+// ARG_PARSE_2:     }
+// ARG_PARSE_2:   ]
+// ARG_PARSE_2:   key.compileid: [[CID1]]
+// ARG_PARSE_2: }
+// ARG_PARSE_2-NOT: compile-will-start
+// ARG_PARSE_2-NOT: compile-did-finish

tools/SourceKit/lib/SwiftLang/SwiftASTManager.cpp

@@ -512,8 +512,26 @@ SwiftInvocationRef
 SwiftASTManager::getInvocation(ArrayRef<const char *> OrigArgs,
                                StringRef PrimaryFile,
                                std::string &Error) {
+
+  DiagnosticEngine Diags(Impl.SourceMgr);
+  EditorDiagConsumer CollectDiagConsumer;
+  Diags.addConsumer(CollectDiagConsumer);
+
   CompilerInvocation CompInvok;
-  if (initCompilerInvocation(CompInvok, OrigArgs, PrimaryFile, Error)) {
+  if (initCompilerInvocation(CompInvok, OrigArgs, Diags, PrimaryFile, Error)) {
+    // We create a traced operation here to represent the failure to parse
+    // arguments since we cannot reach `createAST` where that would normally
+    // happen.
+    trace::TracedOperation TracedOp(trace::OperationKind::PerformSema);
+    if (TracedOp.enabled()) {
+      trace::SwiftInvocation TraceInfo;
+      trace::initTraceInfo(TraceInfo, PrimaryFile, OrigArgs);
+      TracedOp.setDiagnosticProvider(
+        [&CollectDiagConsumer](SmallVectorImpl<DiagnosticEntryInfo> &diags) {
+          CollectDiagConsumer.getAllDiagnostics(diags);
+        });
+      TracedOp.start(TraceInfo);
+    }
     return nullptr;
   }