Avoid undefined behaviour in operator~.

Change-Id: I4fba27cfc4c9c59e5d7a1fc6746639fd60ed0742 Reviewed-on: https://code-review.googlesource.com/12391 Reviewed-by: Paul Wankadia <[email protected]>
google · Apr 21, 2017 · ade2c95 · ade2c95
1 parent fa80121
commit ade2c95
Showing 1 changed file with 52 additions and 47 deletions.
diff --git a/re2/regexp.h b/re2/regexp.h
@@ -276,44 +276,45 @@ class Regexp {
 
   // Flags for parsing.  Can be ORed together.
   enum ParseFlags {
-    NoParseFlags = 0,
-    FoldCase     = 1<<0,   // Fold case during matching (case-insensitive).
-    Literal      = 1<<1,   // Treat s as literal string instead of a regexp.
-    ClassNL      = 1<<2,   // Allow char classes like [^a-z] and \D and \s
-                           // and [[:space:]] to match newline.
-    DotNL        = 1<<3,   // Allow . to match newline.
-    MatchNL      = ClassNL | DotNL,
-    OneLine      = 1<<4,   // Treat ^ and $ as only matching at beginning and
-                           // end of text, not around embedded newlines.
-                           // (Perl's default)
-    Latin1       = 1<<5,   // Regexp and text are in Latin1, not UTF-8.
-    NonGreedy    = 1<<6,   // Repetition operators are non-greedy by default.
-    PerlClasses  = 1<<7,   // Allow Perl character classes like \d.
-    PerlB        = 1<<8,   // Allow Perl's \b and \B.
-    PerlX        = 1<<9,   // Perl extensions:
-                           //   non-capturing parens - (?: )
-                           //   non-greedy operators - *? +? ?? {}?
-                           //   flag edits - (?i) (?-i) (?i: )
-                           //     i - FoldCase
-                           //     m - !OneLine
-                           //     s - DotNL
-                           //     U - NonGreedy
-                           //   line ends: \A \z
-                           //   \Q and \E to disable/enable metacharacters
-                           //   (?P<name>expr) for named captures
-                           //   \C to match any single byte
-    UnicodeGroups = 1<<10, // Allow \p{Han} for Unicode Han group
-                           //   and \P{Han} for its negation.
-    NeverNL      = 1<<11,  // Never match NL, even if the regexp mentions
-                           //   it explicitly.
-    NeverCapture = 1<<12,  // Parse all parens as non-capturing.
+    NoParseFlags  = 0,
+    FoldCase      = 1<<0,   // Fold case during matching (case-insensitive).
+    Literal       = 1<<1,   // Treat s as literal string instead of a regexp.
+    ClassNL       = 1<<2,   // Allow char classes like [^a-z] and \D and \s
+                            // and [[:space:]] to match newline.
+    DotNL         = 1<<3,   // Allow . to match newline.
+    MatchNL       = ClassNL | DotNL,
+    OneLine       = 1<<4,   // Treat ^ and $ as only matching at beginning and
+                            // end of text, not around embedded newlines.
+                            // (Perl's default)
+    Latin1        = 1<<5,   // Regexp and text are in Latin1, not UTF-8.
+    NonGreedy     = 1<<6,   // Repetition operators are non-greedy by default.
+    PerlClasses   = 1<<7,   // Allow Perl character classes like \d.
+    PerlB         = 1<<8,   // Allow Perl's \b and \B.
+    PerlX         = 1<<9,   // Perl extensions:
+                            //   non-capturing parens - (?: )
+                            //   non-greedy operators - *? +? ?? {}?
+                            //   flag edits - (?i) (?-i) (?i: )
+                            //     i - FoldCase
+                            //     m - !OneLine
+                            //     s - DotNL
+                            //     U - NonGreedy
+                            //   line ends: \A \z
+                            //   \Q and \E to disable/enable metacharacters
+                            //   (?P<name>expr) for named captures
+                            //   \C to match any single byte
+    UnicodeGroups = 1<<10,  // Allow \p{Han} for Unicode Han group
+                            //   and \P{Han} for its negation.
+    NeverNL       = 1<<11,  // Never match NL, even if the regexp mentions
+                            //   it explicitly.
+    NeverCapture  = 1<<12,  // Parse all parens as non-capturing.
 
     // As close to Perl as we can get.
-    LikePerl     = ClassNL | OneLine | PerlClasses | PerlB | PerlX |
-                   UnicodeGroups,
+    LikePerl      = ClassNL | OneLine | PerlClasses | PerlB | PerlX |
+                    UnicodeGroups,
 
     // Internal use only.
-    WasDollar    = 1<<15,  // on kRegexpEndText: was $ in regexp text
+    WasDollar     = 1<<13,  // on kRegexpEndText: was $ in regexp text
+    AllParseFlags = (1<<14)-1,
   };
 
   // Get.  No set, Regexps are logically immutable once created.
@@ -620,25 +621,29 @@ class CharClassBuilder {
   CharClassBuilder& operator=(const CharClassBuilder&) = delete;
 };
 
-// Tell g++ that bitwise ops on ParseFlags produce ParseFlags.
-inline Regexp::ParseFlags operator|(Regexp::ParseFlags a, Regexp::ParseFlags b)
-{
-  return static_cast<Regexp::ParseFlags>(static_cast<int>(a) | static_cast<int>(b));
+// Bitwise ops on ParseFlags produce ParseFlags.
+inline Regexp::ParseFlags operator|(Regexp::ParseFlags a,
+                                    Regexp::ParseFlags b) {
+  return static_cast<Regexp::ParseFlags>(
+      static_cast<int>(a) | static_cast<int>(b));
 }
 
-inline Regexp::ParseFlags operator^(Regexp::ParseFlags a, Regexp::ParseFlags b)
-{
-  return static_cast<Regexp::ParseFlags>(static_cast<int>(a) ^ static_cast<int>(b));
+inline Regexp::ParseFlags operator^(Regexp::ParseFlags a,
+                                    Regexp::ParseFlags b) {
+  return static_cast<Regexp::ParseFlags>(
+      static_cast<int>(a) ^ static_cast<int>(b));
 }
 
-inline Regexp::ParseFlags operator&(Regexp::ParseFlags a, Regexp::ParseFlags b)
-{
-  return static_cast<Regexp::ParseFlags>(static_cast<int>(a) & static_cast<int>(b));
+inline Regexp::ParseFlags operator&(Regexp::ParseFlags a,
+                                    Regexp::ParseFlags b) {
+  return static_cast<Regexp::ParseFlags>(
+      static_cast<int>(a) & static_cast<int>(b));
 }
 
-inline Regexp::ParseFlags operator~(Regexp::ParseFlags a)
-{
-  return static_cast<Regexp::ParseFlags>(~static_cast<int>(a));
+inline Regexp::ParseFlags operator~(Regexp::ParseFlags a) {
+  // Attempting to produce a value out of enum's range has undefined behaviour.
+  return static_cast<Regexp::ParseFlags>(
+      ~static_cast<int>(a) & static_cast<int>(Regexp::AllParseFlags));
 }
 
 }  // namespace re2