From bfa65301f1239d31249132fd8821bb1fe7124958 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 21 Jul 2026 10:36:49 +0000
Subject: [PATCH] Commit 9: Fix hasLocationInfo for all string literal forms;
 fix unicode escape
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

RegexTreeView.qll - hasLocationInfo fix (RULE 4):
- Add regexpContentOffset(RegExp re) private helper that computes the correct
  number of source chars before the first content char, from getValueText():
  - Plain "...":          offset 1
  - L"...":               offset 2 (L" prefix)
  - u8"...":              offset 3 (u8" prefix)
  - R"(...)":             offset 3 (R"( opener)
  - R"x(...)x":          offset 4 (R"x( with custom delim)
  - LR"(...)":            offset 4 (LR"()
  - Uses vt.matches("%R\"%(%") to detect raw strings; finds '(' position
  - For non-raw, finds '"' position
- Replace hardcoded `+ 1` with `+ regexpContentOffset(re)` in hasLocationInfo
- Update comment: documents plain/encoding/raw/combined forms, notes that
  escaped non-raw strings are approximate (mirroring Java/Python)

test.cpp:
- Fix r_uni: change "\\u{9879}" to "\\u9879" — braced \u{...} is not standard
  C++ regex syntax; the 4-digit \uHHHH form is valid ECMAScript \u escape

Regenerated all 3 .expected files via codeql test run --learn (CodeQL 2.26.1).
All 3 tests pass.

Location test confirms:
- Plain "a+b" (line 144): litStartCol 22 → termStartCol 23 (22+1)  UNCHANGED ✓
- Raw R"(a+b)" (line 147): litStartCol 20 → termStartCol 23 (20+3)  FIXED ✓
- Raw R"x(a+b)x" (line 156): litStartCol 21 → termStartCol 25 (21+4) FIXED ✓
- L"a+b" (line 159): litStartCol 22 → termStartCol 24 (22+2)         FIXED ✓
- LR"(a+b)" (line 162): litStartCol 26 → termStartCol 30 (26+4)      FIXED ✓
---
 .../semmle/code/cpp/regex/RegexTreeView.qll   | 54 +++++++++--
 .../library-tests/regex/locations.expected    | 60 ++++++------
 .../test/library-tests/regex/parse.expected   |  2 +-
 .../test/library-tests/regex/regexp.expected  | 92 +++++++++----------
 cpp/ql/test/library-tests/regex/test.cpp      |  4 +-
 5 files changed, 127 insertions(+), 85 deletions(-)

diff --git a/cpp/ql/lib/semmle/code/cpp/regex/RegexTreeView.qll b/cpp/ql/lib/semmle/code/cpp/regex/RegexTreeView.qll
index 23a585a162b..1cd5896a16c 100644
--- a/cpp/ql/lib/semmle/code/cpp/regex/RegexTreeView.qll
+++ b/cpp/ql/lib/semmle/code/cpp/regex/RegexTreeView.qll
@@ -114,6 +114,36 @@ private module Impl implements RegexTreeViewSig {
     override string getAPrimaryQlClass() { result = "RegExpLiteral" }
   }
 
+  /**
+   * Gets the number of source characters from the start of the string literal `re`
+   * to the first content character (i.e., past the opening delimiter).
+   *
+   * This is derived from the raw source spelling via `StringLiteral.getValueText()`:
+   * - Plain `"..."`:                offset 1  (just the `"`)
+   * - Encoding prefix `L"..."`:     offset 2  (`L"`)
+   * - Encoding prefix `u8"..."`:    offset 3  (`u8"`)
+   * - Raw `R"(...)"`                offset 3  (`R"(`)
+   * - Custom-delim raw `R"x(...)x"` offset 4  (`R"x(` — delim length 1)
+   * - Combined `LR"(...)"`          offset 4  (`LR"(`)
+   *
+   * For non-raw strings, the value-offset maps 1:1 to source columns only when
+   * there are no escape sequences; escaped non-raw strings are approximate
+   * (mirroring Java/Python regex libraries).
+   */
+  private int regexpContentOffset(RegExp re) {
+    exists(string vt | vt = re.getValueText() |
+      // Raw string: find the '(' that opens the raw content.
+      // getValueText() for raw strings looks like: [prefix]R"[delim](...)[delim]"
+      // The opening '(' is after the optional prefix, 'R', '"', and custom delimiter.
+      vt.matches("%R\"%(%") and
+      result = 1 + min(int i | vt.charAt(i) = "(" and i >= 1)
+      or
+      // Non-raw string: find the opening '"'.
+      not vt.matches("%R\"%(%") and
+      result = 1 + min(int i | vt.charAt(i) = "\"")
+    )
+  }
+
   /**
    * A regular expression term, that is, a syntactic part of a regular expression.
    */
@@ -211,18 +241,30 @@ private module Impl implements RegexTreeViewSig {
      */
     Location getLocation() { result = re.getLocation() }
 
-    /** Holds if this term is found at the specified location offsets.
+    /**
+     * Holds if this term is found at the specified location offsets.
      *
-     * Note: for commit 2, this uses an approximate offset of 1 for the
-     * opening delimiter. Commits 8-9 fix this for all string literal forms.
+     * The content offset is computed from `StringLiteral.getValueText()` (the raw source
+     * spelling including delimiters), so it is correct for:
+     * - Plain `"..."`:              offset 1  (`"`)
+     * - Encoding prefixes `L"..."`: offset 2  (`L"`)
+     * - Encoding prefix `u8"..."`:  offset 3  (`u8"`)
+     * - Raw `R"(...)"`              offset 3  (`R"(`)
+     * - Custom-delim raw `R"x(...)x"`: offset 4+len(delim) (`R"` + delim + `(`)
+     * - Combined, e.g. `LR"(...)"`  offset 4  (`LR"(`)
+     *
+     * Note: for non-raw strings, the value-string offset equals the source-column offset
+     * only when there are no escape sequences. Escaped characters are an approximation,
+     * mirroring the Java/Python regex libraries.
      */
     predicate hasLocationInfo(
       string filepath, int startline, int startcolumn, int endline, int endcolumn
     ) {
-      exists(int re_start |
+      exists(int re_start, int offset |
         re.getLocation().hasLocationInfo(filepath, startline, re_start, endline, _) and
-        startcolumn = re_start + 1 + start and
-        endcolumn = re_start + 1 + end - 1
+        offset = regexpContentOffset(re) and
+        startcolumn = re_start + offset + start and
+        endcolumn = re_start + offset + end - 1
       )
     }
 
diff --git a/cpp/ql/test/library-tests/regex/locations.expected b/cpp/ql/test/library-tests/regex/locations.expected
index 52d1b7103d9..d465969f899 100644
--- a/cpp/ql/test/library-tests/regex/locations.expected
+++ b/cpp/ql/test/library-tests/regex/locations.expected
@@ -2,36 +2,36 @@
 | test.cpp:144:23:144:24 | a+ | 22 | 0 | 2 | 23 | 24 |
 | test.cpp:144:23:144:25 | a+b | 22 | 0 | 3 | 23 | 25 |
 | test.cpp:144:25:144:25 | b | 22 | 2 | 3 | 25 | 25 |
-| test.cpp:147:21:147:21 | a | 20 | 0 | 1 | 21 | 21 |
-| test.cpp:147:21:147:22 | a+ | 20 | 0 | 2 | 21 | 22 |
-| test.cpp:147:21:147:23 | a+b | 20 | 0 | 3 | 21 | 23 |
-| test.cpp:147:23:147:23 | b | 20 | 2 | 3 | 23 | 23 |
-| test.cpp:150:22:150:23 | \\s | 21 | 0 | 2 | 22 | 23 |
-| test.cpp:150:22:150:24 | \\s+ | 21 | 0 | 3 | 22 | 24 |
-| test.cpp:150:22:150:25 | \\s+$ | 21 | 0 | 4 | 22 | 25 |
-| test.cpp:150:25:150:25 | $ | 21 | 3 | 4 | 25 | 25 |
-| test.cpp:153:22:153:23 | \\( | 21 | 0 | 2 | 22 | 23 |
-| test.cpp:153:22:153:35 | \\(([,\\w]+)+\\)$ | 21 | 0 | 14 | 22 | 35 |
-| test.cpp:153:24:153:31 | ([,\\w]+) | 21 | 2 | 10 | 24 | 31 |
-| test.cpp:153:24:153:32 | ([,\\w]+)+ | 21 | 2 | 11 | 24 | 32 |
-| test.cpp:153:25:153:29 | [,\\w] | 21 | 3 | 8 | 25 | 29 |
-| test.cpp:153:25:153:30 | [,\\w]+ | 21 | 3 | 9 | 25 | 30 |
-| test.cpp:153:26:153:26 | , | 21 | 4 | 5 | 26 | 26 |
-| test.cpp:153:27:153:28 | \\w | 21 | 5 | 7 | 27 | 28 |
-| test.cpp:153:33:153:34 | \\) | 21 | 11 | 13 | 33 | 34 |
-| test.cpp:153:35:153:35 | $ | 21 | 13 | 14 | 35 | 35 |
-| test.cpp:156:22:156:22 | a | 21 | 0 | 1 | 22 | 22 |
-| test.cpp:156:22:156:23 | a+ | 21 | 0 | 2 | 22 | 23 |
-| test.cpp:156:22:156:24 | a+b | 21 | 0 | 3 | 22 | 24 |
-| test.cpp:156:24:156:24 | b | 21 | 2 | 3 | 24 | 24 |
-| test.cpp:159:23:159:23 | a | 22 | 0 | 1 | 23 | 23 |
-| test.cpp:159:23:159:24 | a+ | 22 | 0 | 2 | 23 | 24 |
-| test.cpp:159:23:159:25 | a+b | 22 | 0 | 3 | 23 | 25 |
-| test.cpp:159:25:159:25 | b | 22 | 2 | 3 | 25 | 25 |
-| test.cpp:162:27:162:27 | a | 26 | 0 | 1 | 27 | 27 |
-| test.cpp:162:27:162:28 | a+ | 26 | 0 | 2 | 27 | 28 |
-| test.cpp:162:27:162:29 | a+b | 26 | 0 | 3 | 27 | 29 |
-| test.cpp:162:29:162:29 | b | 26 | 2 | 3 | 29 | 29 |
+| test.cpp:147:23:147:23 | a | 20 | 0 | 1 | 23 | 23 |
+| test.cpp:147:23:147:24 | a+ | 20 | 0 | 2 | 23 | 24 |
+| test.cpp:147:23:147:25 | a+b | 20 | 0 | 3 | 23 | 25 |
+| test.cpp:147:25:147:25 | b | 20 | 2 | 3 | 25 | 25 |
+| test.cpp:150:24:150:25 | \\s | 21 | 0 | 2 | 24 | 25 |
+| test.cpp:150:24:150:26 | \\s+ | 21 | 0 | 3 | 24 | 26 |
+| test.cpp:150:24:150:27 | \\s+$ | 21 | 0 | 4 | 24 | 27 |
+| test.cpp:150:27:150:27 | $ | 21 | 3 | 4 | 27 | 27 |
+| test.cpp:153:24:153:25 | \\( | 21 | 0 | 2 | 24 | 25 |
+| test.cpp:153:24:153:37 | \\(([,\\w]+)+\\)$ | 21 | 0 | 14 | 24 | 37 |
+| test.cpp:153:26:153:33 | ([,\\w]+) | 21 | 2 | 10 | 26 | 33 |
+| test.cpp:153:26:153:34 | ([,\\w]+)+ | 21 | 2 | 11 | 26 | 34 |
+| test.cpp:153:27:153:31 | [,\\w] | 21 | 3 | 8 | 27 | 31 |
+| test.cpp:153:27:153:32 | [,\\w]+ | 21 | 3 | 9 | 27 | 32 |
+| test.cpp:153:28:153:28 | , | 21 | 4 | 5 | 28 | 28 |
+| test.cpp:153:29:153:30 | \\w | 21 | 5 | 7 | 29 | 30 |
+| test.cpp:153:35:153:36 | \\) | 21 | 11 | 13 | 35 | 36 |
+| test.cpp:153:37:153:37 | $ | 21 | 13 | 14 | 37 | 37 |
+| test.cpp:156:25:156:25 | a | 21 | 0 | 1 | 25 | 25 |
+| test.cpp:156:25:156:26 | a+ | 21 | 0 | 2 | 25 | 26 |
+| test.cpp:156:25:156:27 | a+b | 21 | 0 | 3 | 25 | 27 |
+| test.cpp:156:27:156:27 | b | 21 | 2 | 3 | 27 | 27 |
+| test.cpp:159:24:159:24 | a | 22 | 0 | 1 | 24 | 24 |
+| test.cpp:159:24:159:25 | a+ | 22 | 0 | 2 | 24 | 25 |
+| test.cpp:159:24:159:26 | a+b | 22 | 0 | 3 | 24 | 26 |
+| test.cpp:159:26:159:26 | b | 22 | 2 | 3 | 26 | 26 |
+| test.cpp:162:30:162:30 | a | 26 | 0 | 1 | 30 | 30 |
+| test.cpp:162:30:162:31 | a+ | 26 | 0 | 2 | 30 | 31 |
+| test.cpp:162:30:162:32 | a+b | 26 | 0 | 3 | 30 | 32 |
+| test.cpp:162:32:162:32 | b | 26 | 2 | 3 | 32 | 32 |
 | test.cpp:166:22:166:23 | \\s | 21 | 0 | 2 | 22 | 23 |
 | test.cpp:166:22:166:24 | \\s+ | 21 | 0 | 3 | 22 | 24 |
 | test.cpp:169:22:169:22 | a | 21 | 0 | 1 | 22 | 22 |
diff --git a/cpp/ql/test/library-tests/regex/parse.expected b/cpp/ql/test/library-tests/regex/parse.expected
index 7298205ebd6..cb4bbfdb3cf 100644
--- a/cpp/ql/test/library-tests/regex/parse.expected
+++ b/cpp/ql/test/library-tests/regex/parse.expected
@@ -521,7 +521,7 @@ test.cpp:
 
 #  131| [RegExpNamedCharacterProperty] [:digit:]
 
-#  136| [RegExpConstant, RegExpEscape] \u{987
+#  136| [RegExpConstant, RegExpEscape] \u9879
 
 #  144| [RegExpConstant, RegExpNormalChar] a
 
diff --git a/cpp/ql/test/library-tests/regex/regexp.expected b/cpp/ql/test/library-tests/regex/regexp.expected
index d5e9979aed4..d934025e3a6 100644
--- a/cpp/ql/test/library-tests/regex/regexp.expected
+++ b/cpp/ql/test/library-tests/regex/regexp.expected
@@ -8,7 +8,7 @@ groupNumber
 | test.cpp:108:21:108:30 | (?<id>\\w+) | 1 |
 | test.cpp:112:23:112:26 | (a+) | 1 |
 | test.cpp:113:23:113:32 | (?<qux>q+) | 1 |
-| test.cpp:153:24:153:31 | ([,\\w]+) | 1 |
+| test.cpp:153:26:153:33 | ([,\\w]+) | 1 |
 term
 | test.cpp:33:21:33:23 | abc | RegExpConstant,RegExpNormalChar |
 | test.cpp:36:22:36:22 | a | RegExpConstant,RegExpNormalChar |
@@ -201,41 +201,41 @@ term
 | test.cpp:128:37:128:39 | a-f | RegExpCharacterRange |
 | test.cpp:128:39:128:39 | f | RegExpConstant,RegExpNormalChar |
 | test.cpp:131:24:131:32 | [:digit:] | RegExpNamedCharacterProperty |
-| test.cpp:136:21:136:26 | \\u{987 | RegExpConstant,RegExpEscape |
+| test.cpp:136:21:136:26 | \\u9879 | RegExpConstant,RegExpEscape |
 | test.cpp:144:23:144:23 | a | RegExpConstant,RegExpNormalChar |
 | test.cpp:144:23:144:24 | a+ | RegExpPlus |
 | test.cpp:144:23:144:25 | a+b | RegExpSequence |
 | test.cpp:144:25:144:25 | b | RegExpConstant,RegExpNormalChar |
-| test.cpp:147:21:147:21 | a | RegExpConstant,RegExpNormalChar |
-| test.cpp:147:21:147:22 | a+ | RegExpPlus |
-| test.cpp:147:21:147:23 | a+b | RegExpSequence |
-| test.cpp:147:23:147:23 | b | RegExpConstant,RegExpNormalChar |
-| test.cpp:150:22:150:23 | \\s | RegExpCharacterClassEscape |
-| test.cpp:150:22:150:24 | \\s+ | RegExpPlus |
-| test.cpp:150:22:150:25 | \\s+$ | RegExpSequence |
-| test.cpp:150:25:150:25 | $ | RegExpDollar |
-| test.cpp:153:22:153:23 | \\( | RegExpConstant,RegExpEscape |
-| test.cpp:153:22:153:35 | \\(([,\\w]+)+\\)$ | RegExpSequence |
-| test.cpp:153:24:153:31 | ([,\\w]+) | RegExpGroup |
-| test.cpp:153:24:153:32 | ([,\\w]+)+ | RegExpPlus |
-| test.cpp:153:25:153:29 | [,\\w] | RegExpCharacterClass |
-| test.cpp:153:25:153:30 | [,\\w]+ | RegExpPlus |
-| test.cpp:153:26:153:26 | , | RegExpConstant,RegExpNormalChar |
-| test.cpp:153:27:153:28 | \\w | RegExpCharacterClassEscape |
-| test.cpp:153:33:153:34 | \\) | RegExpConstant,RegExpEscape |
-| test.cpp:153:35:153:35 | $ | RegExpDollar |
-| test.cpp:156:22:156:22 | a | RegExpConstant,RegExpNormalChar |
-| test.cpp:156:22:156:23 | a+ | RegExpPlus |
-| test.cpp:156:22:156:24 | a+b | RegExpSequence |
-| test.cpp:156:24:156:24 | b | RegExpConstant,RegExpNormalChar |
-| test.cpp:159:23:159:23 | a | RegExpConstant,RegExpNormalChar |
-| test.cpp:159:23:159:24 | a+ | RegExpPlus |
-| test.cpp:159:23:159:25 | a+b | RegExpSequence |
-| test.cpp:159:25:159:25 | b | RegExpConstant,RegExpNormalChar |
-| test.cpp:162:27:162:27 | a | RegExpConstant,RegExpNormalChar |
-| test.cpp:162:27:162:28 | a+ | RegExpPlus |
-| test.cpp:162:27:162:29 | a+b | RegExpSequence |
-| test.cpp:162:29:162:29 | b | RegExpConstant,RegExpNormalChar |
+| test.cpp:147:23:147:23 | a | RegExpConstant,RegExpNormalChar |
+| test.cpp:147:23:147:24 | a+ | RegExpPlus |
+| test.cpp:147:23:147:25 | a+b | RegExpSequence |
+| test.cpp:147:25:147:25 | b | RegExpConstant,RegExpNormalChar |
+| test.cpp:150:24:150:25 | \\s | RegExpCharacterClassEscape |
+| test.cpp:150:24:150:26 | \\s+ | RegExpPlus |
+| test.cpp:150:24:150:27 | \\s+$ | RegExpSequence |
+| test.cpp:150:27:150:27 | $ | RegExpDollar |
+| test.cpp:153:24:153:25 | \\( | RegExpConstant,RegExpEscape |
+| test.cpp:153:24:153:37 | \\(([,\\w]+)+\\)$ | RegExpSequence |
+| test.cpp:153:26:153:33 | ([,\\w]+) | RegExpGroup |
+| test.cpp:153:26:153:34 | ([,\\w]+)+ | RegExpPlus |
+| test.cpp:153:27:153:31 | [,\\w] | RegExpCharacterClass |
+| test.cpp:153:27:153:32 | [,\\w]+ | RegExpPlus |
+| test.cpp:153:28:153:28 | , | RegExpConstant,RegExpNormalChar |
+| test.cpp:153:29:153:30 | \\w | RegExpCharacterClassEscape |
+| test.cpp:153:35:153:36 | \\) | RegExpConstant,RegExpEscape |
+| test.cpp:153:37:153:37 | $ | RegExpDollar |
+| test.cpp:156:25:156:25 | a | RegExpConstant,RegExpNormalChar |
+| test.cpp:156:25:156:26 | a+ | RegExpPlus |
+| test.cpp:156:25:156:27 | a+b | RegExpSequence |
+| test.cpp:156:27:156:27 | b | RegExpConstant,RegExpNormalChar |
+| test.cpp:159:24:159:24 | a | RegExpConstant,RegExpNormalChar |
+| test.cpp:159:24:159:25 | a+ | RegExpPlus |
+| test.cpp:159:24:159:26 | a+b | RegExpSequence |
+| test.cpp:159:26:159:26 | b | RegExpConstant,RegExpNormalChar |
+| test.cpp:162:30:162:30 | a | RegExpConstant,RegExpNormalChar |
+| test.cpp:162:30:162:31 | a+ | RegExpPlus |
+| test.cpp:162:30:162:32 | a+b | RegExpSequence |
+| test.cpp:162:32:162:32 | b | RegExpConstant,RegExpNormalChar |
 | test.cpp:166:22:166:23 | \\s | RegExpCharacterClassEscape |
 | test.cpp:166:22:166:24 | \\s+ | RegExpPlus |
 | test.cpp:169:22:169:22 | a | RegExpConstant,RegExpNormalChar |
@@ -318,22 +318,22 @@ regExpNormalCharValue
 | test.cpp:128:27:128:27 | F | F |
 | test.cpp:128:37:128:37 | a | a |
 | test.cpp:128:39:128:39 | f | f |
-| test.cpp:136:21:136:26 | \\u{987 | \u0987 |
+| test.cpp:136:21:136:26 | \\u9879 | \u9879 |
 | test.cpp:144:23:144:23 | a | a |
 | test.cpp:144:25:144:25 | b | b |
-| test.cpp:147:21:147:21 | a | a |
-| test.cpp:147:23:147:23 | b | b |
-| test.cpp:150:22:150:23 | \\s | s |
-| test.cpp:153:22:153:23 | \\( | ( |
-| test.cpp:153:26:153:26 | , | , |
-| test.cpp:153:27:153:28 | \\w | w |
-| test.cpp:153:33:153:34 | \\) | ) |
-| test.cpp:156:22:156:22 | a | a |
-| test.cpp:156:24:156:24 | b | b |
-| test.cpp:159:23:159:23 | a | a |
-| test.cpp:159:25:159:25 | b | b |
-| test.cpp:162:27:162:27 | a | a |
-| test.cpp:162:29:162:29 | b | b |
+| test.cpp:147:23:147:23 | a | a |
+| test.cpp:147:25:147:25 | b | b |
+| test.cpp:150:24:150:25 | \\s | s |
+| test.cpp:153:24:153:25 | \\( | ( |
+| test.cpp:153:28:153:28 | , | , |
+| test.cpp:153:29:153:30 | \\w | w |
+| test.cpp:153:35:153:36 | \\) | ) |
+| test.cpp:156:25:156:25 | a | a |
+| test.cpp:156:27:156:27 | b | b |
+| test.cpp:159:24:159:24 | a | a |
+| test.cpp:159:26:159:26 | b | b |
+| test.cpp:162:30:162:30 | a | a |
+| test.cpp:162:32:162:32 | b | b |
 | test.cpp:166:22:166:23 | \\s | s |
 | test.cpp:169:22:169:22 | a | a |
 | test.cpp:169:23:169:24 | \\. | . |
diff --git a/cpp/ql/test/library-tests/regex/test.cpp b/cpp/ql/test/library-tests/regex/test.cpp
index 67cb3a050c6..e363570807a 100644
--- a/cpp/ql/test/library-tests/regex/test.cpp
+++ b/cpp/ql/test/library-tests/regex/test.cpp
@@ -132,8 +132,8 @@ void test() {
 
   // Dropped: /#{A}bc/ — Ruby string interpolation, no C++ string-literal form.
 
-  // unicode: \u{9879} in C++ (Ruby unicode escape syntax)
-  std::regex r_uni("\\u{9879}");
+  // unicode: \uHHHH 4-digit hex form (valid ECMAScript \u escape in std::regex)
+  std::regex r_uni("\\u9879");
 }
 
 // Location tests (commit 8: pre-fix columns; commit 9: fixes raw/prefixed offsets).