From af4b13837a025a4281ac643b457eeac477cad39e Mon Sep 17 00:00:00 2001
From: Liam Miller-Cushon <cushon@google.com>
Date: Thu, 24 Sep 2026 22:54:17 +0300
Subject: [PATCH] Accept a type annotation on the qualifier of a method
 reference

"Supplier<List<?>> a = @A ArrayList::new;" failed with 'did not
generate token "@"'. The printing of a type annotation on a method
reference's qualifier was already in place, but visitMemberReference
first synced to the tree's start position, and javac's start position
for a member reference leaves out the annotation, so the sync reported
the annotation's tokens as never generated.

This ports google/google-java-format#984 by Liam Miller-Cushon:
visitMemberReference no longer syncs to the start position. The golden
B308157568 comes from upstream, with the expected output in this
project's style.

The 15,747 files of the JDK 21 sources format exactly as before.
---
 .../javaformat/java/JavaInputAstVisitor.java  |  3 ++-
 .../javaformat/java/testdata/B308157568.input | 23 +++++++++++++++++++
 .../java/testdata/B308157568.output           | 23 +++++++++++++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/B308157568.input
 create mode 100644 open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/B308157568.output

diff --git a/open-java-format/src/main/java/com/palantir/javaformat/java/JavaInputAstVisitor.java b/open-java-format/src/main/java/com/palantir/javaformat/java/JavaInputAstVisitor.java
index 0fd3569d8..e1710b0ff 100644
--- a/open-java-format/src/main/java/com/palantir/javaformat/java/JavaInputAstVisitor.java
+++ b/open-java-format/src/main/java/com/palantir/javaformat/java/JavaInputAstVisitor.java
@@ -928,7 +928,8 @@ public boolean visitEnumDeclaration(ClassTree node) {
 
     @Override
     public Void visitMemberReference(MemberReferenceTree node, Void unused) {
-        sync(node);
+        // No sync(node): javac's start position for a member reference leaves out a type annotation on its
+        // qualifier ("@A ArrayList::new"), so syncing to it would report the annotation as never generated.
         builder.open(OpenOp.builder()
                 .plusIndent(plusFour)
                 .debugName("methodReference")
diff --git a/open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/B308157568.input b/open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/B308157568.input
new file mode 100644
index 000000000..089a3f1e8
--- /dev/null
+++ b/open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/B308157568.input
@@ -0,0 +1,23 @@
+class C {
+  @A(0x14)
+  int f(Object o) {
+    @A(0x40)
+    int local;
+    try (@A(0x41)
+        JarFile jarFile = new JarFile("hello.jar")) {
+    } catch (
+        @A(0x42)
+        IOException e) {
+    }
+    if (o instanceof @A(0x43) String) {}
+    new @A(0x44) ArrayList<>();
+    Supplier<List<?>> a = @A(0x45) ArrayList::new;
+    Supplier<List<?>> b = @A(0x46) ImmutableList::of;
+    String s = (@A(0x47) String) o;
+    List<?> xs = new ArrayList<@A(0x48) String>();
+    xs = ImmutableList.<@A(0x49) String>of();
+    Supplier<List<?>> c = ArrayList<@A(0x4A) String>::new;
+    Supplier<List<?>> d = ImmutableList::<@A(0x4B) String>of;
+    return 0;
+  }
+}
diff --git a/open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/B308157568.output b/open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/B308157568.output
new file mode 100644
index 000000000..31eb4bdc2
--- /dev/null
+++ b/open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/B308157568.output
@@ -0,0 +1,23 @@
+class C {
+    @A(0x14)
+    int f(Object o) {
+        @A(0x40)
+        int local;
+        try (@A(0x41)
+                JarFile jarFile = new JarFile("hello.jar")) {
+        } catch (
+                @A(0x42)
+                IOException e) {
+        }
+        if (o instanceof @A(0x43) String) {}
+        new @A(0x44) ArrayList<>();
+        Supplier<List<?>> a = @A(0x45) ArrayList::new;
+        Supplier<List<?>> b = @A(0x46) ImmutableList::of;
+        String s = (@A(0x47) String) o;
+        List<?> xs = new ArrayList<@A(0x48) String>();
+        xs = ImmutableList.<@A(0x49) String>of();
+        Supplier<List<?>> c = ArrayList<@A(0x4A) String>::new;
+        Supplier<List<?>> d = ImmutableList::<@A(0x4B) String>of;
+        return 0;
+    }
+}