Fix error reporting for import resolution errors on nested types

MOE_MIGRATED_REVID=222446808

3 files changed, 28 insertions, 5 deletions

diff --git a/java/com/google/turbine/binder/lookup/ImportIndex.java b/java/com/google/turbine/binder/lookup/ImportIndex.java
index f28d905..97556ca 100644
--- a/java/com/google/turbine/binder/lookup/ImportIndex.java
+++ b/java/com/google/turbine/binder/lookup/ImportIndex.java
@@ -105,7 +105,10 @@ public class ImportIndex implements ImportScope {
     }
     ClassSymbol sym = (ClassSymbol) result.sym();
     for (Tree.Ident bit : result.remaining()) {
-      sym = resolveNext(log, i.position(), resolve, sym, bit);
+      sym = resolveNext(log, resolve, sym, bit);
+      if (sym == null) {
+        return null;
+      }
     }
     ClassSymbol resolved = sym;
     return new ImportScope() {
@@ -118,14 +121,15 @@ public class ImportIndex implements ImportScope {
 
   private static ClassSymbol resolveNext(
       TurbineLogWithSource log,
-      int position,
       CanonicalSymbolResolver resolve,
       ClassSymbol sym,
       Ident bit) {
     ClassSymbol next = resolve.resolveOne(sym, bit);
     if (next == null) {
       log.error(
-          position, ErrorKind.SYMBOL_NOT_FOUND, new ClassSymbol(sym.binaryName() + '$' + bit));
+          bit.position(),
+          ErrorKind.SYMBOL_NOT_FOUND,
+          new ClassSymbol(sym.binaryName() + '$' + bit));
     }
     return next;
   }
diff --git a/java/com/google/turbine/binder/lookup/LookupResult.java b/java/com/google/turbine/binder/lookup/LookupResult.java
index 7e0f737..8340386 100644
--- a/java/com/google/turbine/binder/lookup/LookupResult.java
+++ b/java/com/google/turbine/binder/lookup/LookupResult.java
@@ -16,6 +16,8 @@
 
 package com.google.turbine.binder.lookup;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.Immutable;
 import com.google.turbine.binder.sym.ClassSymbol;
@@ -45,7 +47,7 @@ public class LookupResult {
   private final ImmutableList<Tree.Ident> remaining;
 
   public LookupResult(Symbol sym, LookupKey remaining) {
-    this.sym = sym;
+    this.sym = requireNonNull(sym);
     this.remaining = remaining.hasNext() ? remaining.rest().simpleNames() : ImmutableList.of();
   }
 }
diff --git a/javatests/com/google/turbine/binder/BinderErrorTest.java b/javatests/com/google/turbine/binder/BinderErrorTest.java
index f6fb317..bc61e76 100644
--- a/javatests/com/google/turbine/binder/BinderErrorTest.java
+++ b/javatests/com/google/turbine/binder/BinderErrorTest.java
@@ -180,7 +180,7 @@ public class BinderErrorTest {
         {
           "<>:2: error: symbol not found java.util.List$NoSuch", //
           "import java.util.List.NoSuch;",
-          "       ^",
+          "                      ^",
           "<>:3: error: could not resolve NoSuch",
           "public class Test extends NoSuch {",
           "                          ^",
@@ -488,6 +488,23 @@ public class BinderErrorTest {
           "  ^",
         },
       },
+      {
+        {
+          "package p;", //
+          "import java.util.List.NoSuchAnno;",
+          "@NoSuchAnno",
+          "public class Test {",
+          "}",
+        },
+        {
+          "<>:2: error: symbol not found java.util.List$NoSuchAnno",
+          "import java.util.List.NoSuchAnno;",
+          "                      ^",
+          "<>:3: error: could not resolve NoSuchAnno",
+          "@NoSuchAnno",
+          " ^",
+        },
+      },
     };
     return Arrays.asList((Object[][]) testCases);
   }