diff --git a/cpp/ql/test/library-tests/regex/parse.expected b/cpp/ql/test/library-tests/regex/parse.expected
index f5e1a63fbd9..08ed7a2c218 100644
--- a/cpp/ql/test/library-tests/regex/parse.expected
+++ b/cpp/ql/test/library-tests/regex/parse.expected
@@ -29,11 +29,6 @@ test.cpp:
 #   35| [RegExpRange] a{4,8}
 #-----| 0 -> [RegExpConstant, RegExpNormalChar] a
 
-#   36| [RegExpConstant, RegExpNormalChar] a
-
-#   36| [RegExpRange] a{,8}
-#-----| 0 -> [RegExpConstant, RegExpNormalChar] a
-
 #   37| [RegExpConstant, RegExpNormalChar] a
 
 #   37| [InfiniteRepetitionQuantifier, RegExpRange] a{3,}
@@ -202,11 +197,6 @@ test.cpp:
 #   59| [RegExpStar] .*
 #-----| 0 -> [RegExpDot] .
 
-#   60| [RegExpDot] .
-
-#   60| [RegExpStar] .*
-#-----| 0 -> [RegExpDot] .
-
 #   61| [RegExpCharacterClassEscape] \w
 
 #   61| [RegExpPlus] \w+
@@ -348,20 +338,6 @@ test.cpp:
 #   78| [RegExpPlus] \w+
 #-----| 0 -> [RegExpCharacterClassEscape] \w
 
-#   79| [RegExpGroup] (?'foo'fo+)
-#-----| 0 -> [RegExpSequence] fo+
-
-#   79| [RegExpConstant, RegExpNormalChar] f
-
-#   79| [RegExpSequence] fo+
-#-----| 0 -> [RegExpConstant, RegExpNormalChar] f
-#-----| 1 -> [RegExpPlus] o+
-
-#   79| [RegExpConstant, RegExpNormalChar] o
-
-#   79| [RegExpPlus] o+
-#-----| 0 -> [RegExpConstant, RegExpNormalChar] o
-
 #   82| [RegExpGroup] (a+)
 #-----| 0 -> [RegExpPlus] a+
 
diff --git a/cpp/ql/test/library-tests/regex/regexp.expected b/cpp/ql/test/library-tests/regex/regexp.expected
index 5842f67797f..e2d51ce8f82 100644
--- a/cpp/ql/test/library-tests/regex/regexp.expected
+++ b/cpp/ql/test/library-tests/regex/regexp.expected
@@ -1,12 +1,10 @@
 groupName
 | test.cpp:78:21:78:30 | (?<id>\\w+) | id |
-| test.cpp:79:21:79:31 | (?'foo'fo+) | foo |
 | test.cpp:83:23:83:32 | (?<qux>q+) | qux |
 groupNumber
 | test.cpp:72:22:72:26 | (foo) | 1 |
 | test.cpp:73:24:73:28 | (o\|b) | 1 |
 | test.cpp:74:22:74:29 | (a\|b\|cd) | 1 |
-| test.cpp:79:21:79:31 | (?'foo'fo+) | 1 |
 | test.cpp:82:23:82:26 | (a+) | 1 |
 term
 | test.cpp:31:21:31:23 | abc | RegExpConstant,RegExpNormalChar |
@@ -20,8 +18,6 @@ term
 | test.cpp:34:28:34:28 | d | RegExpConstant,RegExpNormalChar |
 | test.cpp:35:22:35:22 | a | RegExpConstant,RegExpNormalChar |
 | test.cpp:35:22:35:27 | a{4,8} | RegExpRange |
-| test.cpp:36:22:36:22 | a | RegExpConstant,RegExpNormalChar |
-| test.cpp:36:22:36:26 | a{,8} | RegExpRange |
 | test.cpp:37:22:37:22 | a | RegExpConstant,RegExpNormalChar |
 | test.cpp:37:22:37:26 | a{3,} | InfiniteRepetitionQuantifier,RegExpRange |
 | test.cpp:38:22:38:22 | a | RegExpConstant,RegExpNormalChar |
@@ -83,8 +79,6 @@ term
 | test.cpp:56:30:56:33 | A-F] | RegExpConstant,RegExpNormalChar |
 | test.cpp:59:23:59:23 | . | RegExpDot |
 | test.cpp:59:23:59:24 | .* | RegExpStar |
-| test.cpp:60:24:60:24 | . | RegExpDot |
-| test.cpp:60:24:60:25 | .* | RegExpStar |
 | test.cpp:61:23:61:24 | \\w | RegExpCharacterClassEscape |
 | test.cpp:61:23:61:25 | \\w+ | RegExpPlus |
 | test.cpp:61:23:61:27 | \\w+\\W | RegExpSequence |
@@ -136,11 +130,6 @@ term
 | test.cpp:78:21:78:30 | (?<id>\\w+) | RegExpGroup |
 | test.cpp:78:27:78:28 | \\w | RegExpCharacterClassEscape |
 | test.cpp:78:27:78:29 | \\w+ | RegExpPlus |
-| test.cpp:79:21:79:31 | (?'foo'fo+) | RegExpGroup |
-| test.cpp:79:28:79:28 | f | RegExpConstant,RegExpNormalChar |
-| test.cpp:79:28:79:30 | fo+ | RegExpSequence |
-| test.cpp:79:29:79:29 | o | RegExpConstant,RegExpNormalChar |
-| test.cpp:79:29:79:30 | o+ | RegExpPlus |
 | test.cpp:82:23:82:26 | (a+) | RegExpGroup |
 | test.cpp:82:23:82:30 | (a+)b+\\1 | RegExpSequence |
 | test.cpp:82:24:82:24 | a | RegExpConstant,RegExpNormalChar |
@@ -193,7 +182,6 @@ regExpNormalCharValue
 | test.cpp:34:26:34:26 | c | c |
 | test.cpp:34:28:34:28 | d | d |
 | test.cpp:35:22:35:22 | a | a |
-| test.cpp:36:22:36:22 | a | a |
 | test.cpp:37:22:37:22 | a | a |
 | test.cpp:38:22:38:22 | a | a |
 | test.cpp:41:21:41:23 | foo | foo |
@@ -253,8 +241,6 @@ regExpNormalCharValue
 | test.cpp:75:25:75:25 | : | : |
 | test.cpp:75:28:75:29 | \\w | w |
 | test.cpp:78:27:78:28 | \\w | w |
-| test.cpp:79:28:79:28 | f | f |
-| test.cpp:79:29:79:29 | o | o |
 | test.cpp:82:24:82:24 | a | a |
 | test.cpp:82:27:82:27 | b | b |
 | test.cpp:83:30:83:30 | q | q |
diff --git a/cpp/ql/test/library-tests/regex/test.cpp b/cpp/ql/test/library-tests/regex/test.cpp
index df580fb10eb..1792e2c5abe 100644
--- a/cpp/ql/test/library-tests/regex/test.cpp
+++ b/cpp/ql/test/library-tests/regex/test.cpp
@@ -33,7 +33,7 @@ void test() {
   // Repetition
   std::regex r_rep1("a*b+c?d");
   std::regex r_rep2("a{4,8}");
-  std::regex r_rep3("a{,8}");
+  // Removed: a{,8} — Ruby-only "{,n}" no-lower-bound quantifier (not in ECMAScript)
   std::regex r_rep4("a{3,}");
   std::regex r_rep5("a{7}");
 
@@ -57,7 +57,7 @@ void test() {
 
   // Meta-character classes
   std::regex r_meta1(".*");
-  std::regex r_meta1m(".*"); // /.*/m mode variant — mode flags are constructor args in C++
+  // Removed: /.*/m mode variant — in C++, flags are passed as constructor arg (out of scope)
   std::regex r_meta2("\\w+\\W");
   std::regex r_meta3("\\s\\S");
   std::regex r_meta4("\\d\\D");
@@ -76,7 +76,7 @@ void test() {
 
   // Named groups
   std::regex r_ng1("(?<id>\\w+)");
-  std::regex r_ng2("(?'foo'fo+)"); // single-quote named-group form
+  // Removed: (?'foo'fo+) — Ruby single-quote named-group form (not in ECMAScript)
 
   // Backreferences
   std::regex r_bref1("(a+)b+\\1");