Java 27 and 26: runnable demos and captured output for every JEP, plus version lanes

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01B38FGKKam5SCGgwgduVAh3

scripts/broken-on-27.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# The most useful demonstrations of a preview API are the compile errors. This compiles the same
+# JDK 26 sources with the 26 and the 27 compiler and commits what javac actually said.
+#   ./scripts/broken-on-27.sh   -> docs/output/20-broken-*.txt
+set -uo pipefail
+source "$(dirname "$0")/env.sh"
+SRC="$ROOT/jep-tour/src"
+
+compile() { # jdk-home release file   -> prints javac's own output, then its real exit code
+  local out rc
+  out="$( cd "$SRC/broken" && "$1/bin/javac" --enable-preview --release "$2" -Xlint:-preview -d "$ROOT/build/broken-$2" "$3" 2>&1 )"; rc=$?
+  printf '%s\n' "$out" | grep -v -E '^(Note: |$)' || true
+  echo "exit=$rc"
+}
+
+for f in Pem26Style StructuredScope26 Lazy26; do
+  out="$OUT/20-broken-$(echo "$f" | tr 'A-Z' 'a-z').txt"
+  {
+    echo "\$ javac --enable-preview --release 26 $f.java      (JDK 26)"
+    compile "$JDK26" 26 "$f.java"
+    echo
+    echo "\$ javac --enable-preview --release 27 $f.java      (JDK 27)"
+    compile "$JDK27" 27 "$f.java"
+  } > "$out" 2>&1
+  echo "wrote $out"
+done
+
+{
+  echo "\$ javac --enable-preview --release 27 Dominated.java      (JDK 27)"
+  compile "$JDK27" 27 Dominated.java
+} > "$OUT/20-broken-dominated.txt" 2>&1
+echo "wrote $OUT/20-broken-dominated.txt"