Don't treat missing imports as a fatal error in REPL mode.

We don't want typos in import statements to take down the whole REPL, but we
/do/ want the REPL to be honoring fatal errors that effectively take down the
ASTContext.

This doesn't (yet) apply to the real LLDB REPL, which does not use
SourceFileKind::REPL for its input. The right option to test there is
LangOpts.DebuggerSupport, but that's currently being set for Playgrounds as
well. I've filed <rdar://problem/18090611> for LLDB to adjust their input.

Part of <rdar://problem/17994094>

Swift SVN r21383

include/swift/AST/DiagnosticsSema.def

@@ -88,15 +88,15 @@ NOTE(expression_too_complex,sema,none,
 
 ERROR(sema_no_import,sema_nb,Fatal,
       "no such module '%0'", (StringRef))
-ERROR(sema_no_import_submodule,sema_nb,Fatal,
+ERROR(sema_no_import_repl,sema_nb,none,
-      "no such module", ())
+      "no such module '%0'", (StringRef))
 NOTE(sema_no_import_no_sdk,sema_nb,none,
      "did you forget to set an SDK using -sdk or SDKROOT?", ())
 NOTE(sema_no_import_no_sdk_xcrun,sema_nb,none,
      "use \"xcrun -sdk macosx swift\" to select the default OS X SDK installed "
      "with Xcode", ())
 ERROR(sema_opening_import,sema_nb,Fatal,
-      "opening import file '%0.swift': %1", (StringRef, StringRef))
+      "opening import file for module %0: %1", (Identifier, StringRef))
 
 ERROR(serialization_malformed_module,sema,Fatal,
       "malformed module file: %0", (StringRef))

lib/Immediate/Immediate.cpp

@@ -985,6 +985,9 @@ private:
     }
 
     if (CI.getASTContext().hadError()) {
+      if (CI.getDiags().hasFatalErrorOccurred())
+        return false;
+
       CI.getASTContext().Diags.resetHadAnyError();
       while (REPLInputFile.Decls.size() > RC.CurElem)
         REPLInputFile.Decls.pop_back();

lib/Sema/NameBinding.cpp

@@ -133,14 +133,19 @@ void
 NameBinder::addImport(SmallVectorImpl<std::pair<ImportedModule, bool>> &imports,
                       ImportDecl *ID) {
   Module *M = getModule(ID->getModulePath());
-  if (M == 0) {
+  if (!M) {
-    // FIXME: print entire path regardless.
+    SmallString<64> modulePathStr;
-    if (ID->getModulePath().size() == 1) {
+    interleave(ID->getModulePath(),
-      diagnose(ID->getLoc(), diag::sema_no_import,
+               [&](ImportDecl::AccessPathElement elem) {
-               ID->getModulePath().front().first.str());
+                 modulePathStr += elem.first.str();
-    } else {
+               },
-      diagnose(ID->getLoc(), diag::sema_no_import_submodule);
+               [&] { modulePathStr += "."; });
-    }
+
+    auto diagKind = diag::sema_no_import;
+    if (SF.Kind == SourceFileKind::REPL)
+      diagKind = diag::sema_no_import_repl;
+    diagnose(ID->getLoc(), diagKind, modulePathStr);
+
     if (Context.SearchPathOpts.SDKPath.empty()) {
       diagnose(SourceLoc(), diag::sema_no_import_no_sdk);
       diagnose(SourceLoc(), diag::sema_no_import_no_sdk_xcrun);

lib/Sema/SourceLoader.cpp

@@ -84,7 +84,7 @@ Module *SourceLoader::loadModule(SourceLoc importLoc,
     auto err = inputFileOrError.getError();
     if (err != std::errc::no_such_file_or_directory) {
       Ctx.Diags.diagnose(moduleID.second, diag::sema_opening_import,
-                         moduleID.first.str(), err.message());
+                         moduleID.first, err.message());
     }
 
     return nullptr;

lib/Serialization/SerializedModuleLoader.cpp

@@ -299,7 +299,7 @@ Module *SerializedModuleLoader::loadModule(SourceLoc importLoc,
                                          isFramework)) {
       if (err != std::errc::no_such_file_or_directory) {
         Ctx.Diags.diagnose(moduleID.second, diag::sema_opening_import,
-                           moduleID.first.str(), err.message());
+                           moduleID.first, err.message());
       }
 
       return nullptr;

test/Interpreter/SDK/missing_imports_repl.swift

@@ -1,5 +1,7 @@
-// RUN: %swift -sdk %sdk -repl < %s 2>%t.txt | FileCheck %s
+// RUN: rm -rf %t && mkdir %t
-// RUN: FileCheck -check-prefix CHECK-ERROR %s < %t.txt
+// RUN: touch %t/Corrupted_Module.swiftmodule
+// RUN: not %swift -sdk %sdk -I %t -repl <%s 2>%t/stderr.txt | FileCheck %s
+// RUN: FileCheck -check-prefix CHECK-ERROR %s < %t/stderr.txt
 // REQUIRES: sdk
 // REQUIRES: swift_repl
 
@@ -27,3 +29,10 @@ MKMapRectIsNull(x)
 
 "end"
 // CHECK-NEXT: String = "end"{{$}}
+
+
+import Corrupted_Module
+// CHECK-ERROR: error: malformed module file
+
+"unreached"
+// CHECK-NOT: unreached

test/decl/import/import.swift

@@ -4,7 +4,6 @@
 // RUN: echo "public func foo() -> Int { return false }" > %t/import_text.swift
 // RUN: echo "public func pho$(printf '\xC3\xBB')x() -> Int { return false }" > %t/fran$(printf '\xC3\xA7')ais.swift
 // RUN: %swift %s -I=%t -sdk "" -enable-source-import -verify -show-diagnostics-after-fatal
-// RUN: not %swift %s -I=%t -sdk "" -enable-source-import 2>&1 | FileCheck %s
 
 import Builtin  // expected-error {{no such module 'Builtin'}}
 
@@ -48,8 +47,7 @@ import Swift.import.abc // expected-error 2 {{expected identifier}}
 import where Swift.Int // expected-error {{expected identifier}}
 import 2 // expected-error {{expected identifier}}
 
-// CHECK-NOT: no such module 'really'
+import really.nonexistent // expected-error {{no such module 'really.nonexistent'}}
-import really.nonexistent // expected-error {{no such module}}
 
 
 import import_text // no-warning despite function body problems