fix: place a rewritten block by its longest word, not its last

Signed-off-by: Joseph Kato <joseph@jdkato.io>

Author: jdkato

internal/lint/walk.go

@@ -403,9 +403,18 @@ func (w *walker) advance(text string) int {
 	pos := strings.Index(ctx, last)
 	if pos < 0 {
 		// Extraction rewrites text, so a line is not always a substring of the
-		// source; a single word from it usually still is.
-		if fields := strings.Fields(last); len(fields) > 0 {
-			pos = strings.Index(ctx, fields[len(fields)-1])
+		// source; a single word from it usually still is. The longest word,
+		// though: the final one is as often a short `it.` that appears all
+		// over the document, landing the block on someone else's line -- and
+		// an alert placed by that line is an alert placed on the wrong text.
+		longest := ""
+		for _, f := range strings.Fields(last) {
+			if len(f) > len(longest) {
+				longest = f
+			}
+		}
+		if longest != "" {
+			pos = strings.Index(ctx, longest)
 		}
 	}
 

testdata/e2e/misc.yaml

@@ -200,3 +200,34 @@ cases:
       test.md:3:32:T.Tok:'ZQX' in text
       test.md:5:6:T.Tok:'ZQX' in text
       test.md:5:18:T.Tok:'ZQX' in text
+
+  - name: styled-span-line
+    about: a block located by a common final word (`it.`) landed on another
+      line that happened to hold the same token, and the alert vanished into
+      the dedup -- the block's longest word places it instead
+    files:
+      .vale.ini: |
+        StylesPath = styles
+        MinAlertLevel = suggestion
+
+        [*.md]
+        T.Tok = YES
+      styles/T/Tok.yml: |
+        extends: existence
+        message: "'%s' left in text"
+        level: error
+        nonword: true
+        raw:
+          - ZQX
+      test.md: |
+        A first paragraph in it.
+
+        See **bold prose with a ZQX in it** and *emphasis with a ZQX in it*.
+
+        - A list item with a ZQX in it.
+    args: test.md
+    exit: 1
+    want: |
+      test.md:3:25:T.Tok:'ZQX' left in text
+      test.md:3:58:T.Tok:'ZQX' left in text
+      test.md:5:22:T.Tok:'ZQX' left in text