From f1c47cb7262e6156de090c35b06c5f2b607c768c Mon Sep 17 00:00:00 2001
From: Robin Leroy <egg.robin.leroy@gmail.com>
Date: Sat, 21 Sep 2024 02:19:16 +0200
Subject: [PATCH] Fix line numbers for invariant test failures

---
 .../text/UCD/TestUnicodeInvariants.java       | 23 +++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/unicodetools/src/main/java/org/unicode/text/UCD/TestUnicodeInvariants.java b/unicodetools/src/main/java/org/unicode/text/UCD/TestUnicodeInvariants.java
index ac507c58ed..946b513184 100644
--- a/unicodetools/src/main/java/org/unicode/text/UCD/TestUnicodeInvariants.java
+++ b/unicodetools/src/main/java/org/unicode/text/UCD/TestUnicodeInvariants.java
@@ -184,7 +184,7 @@ public static int testInvariants(String inputFile, String suffix, boolean doRang
                 }
                 final var noComments = new StringBuilder();
                 final List<String> lines = new ArrayList<>();
-                final List<Integer> lineBeginnings = new ArrayList();
+                final List<Integer> lineBeginnings = new ArrayList<>();
                 try (final BufferedReader in = getInputReader(inputFile)) {
                     in.lines()
                             .forEach(
@@ -234,7 +234,26 @@ public static int testInvariants(String inputFile, String suffix, boolean doRang
                         position -> {
                             for (int i = 0; i < lineBeginnings.size(); ++i) {
                                 if (lineBeginnings.get(i) > position.getIndex()) {
-                                    return i; // 1-based line number.
+                                    // The error is before the beginning of line i (0-based), thus
+                                    // on line i
+                                    // (1-based).
+                                    return i;
+                                } else if (lineBeginnings.get(i) == position.getIndex()) {
+                                    // The position in a beginning of line; this happens when an
+                                    // statement has been
+                                    // successfully parsed, but then fails for nonsyntactic reasons.
+                                    // The parse position is then the beginning of the next
+                                    // statement.
+                                    // Backtrack to the last nonempty line (ignoring comments),
+                                    // which is the last
+                                    // line of the failing statement.
+                                    int indexInTrimmedSource = position.getIndex();
+                                    while (lineBeginnings.get(i) == indexInTrimmedSource
+                                            && indexInTrimmedSource > 0) {
+                                        --indexInTrimmedSource;
+                                        --i;
+                                    }
+                                    return i + 1;
                                 }
                             }
                             return lineBeginnings.size();