Change semantics of regex expectations in the diagnostic verifier

Previously, a line like

  // expected-error-re {{foo}}

treats the entirety of foo as a regex. This is inconvenient when matching type
names containing regex characters. For example, to match
"void *(class test8::A::*)(void)" inside such a regex, one would have to type
"void \*\(class test8::A::\*\)\(void\)".

This patch changes the semantics of expected-error-re to only treat the parts
of the directive wrapped in double curly braces as regexes. This avoids the
escaping problem and leads to nicer patterns for those cases; see e.g. the
change to test/Sema/format-strings-scanf.c.

(The balanced search for closing }} of a directive also makes us handle the
full directive in test\SemaCXX\constexpr-printing.cpp:41 and :53.)

Differential Revision: http://llvm-reviews.chandlerc.com/D2388

llvm-svn: 197092

1 files changed, 91 insertions, 6 deletions

diff --git a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
index 77901a73e15..b53fde257de 100644
--- a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
+++ b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
@@ -181,8 +181,8 @@ public:
 class RegexDirective : public Directive {
 public:
   RegexDirective(SourceLocation DirectiveLoc, SourceLocation DiagnosticLoc,
-                 StringRef Text, unsigned Min, unsigned Max)
-    : Directive(DirectiveLoc, DiagnosticLoc, Text, Min, Max), Regex(Text) { }
+                 StringRef Text, unsigned Min, unsigned Max, StringRef RegexStr)
+    : Directive(DirectiveLoc, DiagnosticLoc, Text, Min, Max), Regex(RegexStr) { }
 
   virtual bool isValid(std::string &Error) {
     if (Regex.isValid(Error))
@@ -249,6 +249,30 @@ public:
     return false;
   }
 
+  // Return true if a CloseBrace that closes the OpenBrace at the current nest
+  // level is found. When true, P marks begin-position of CloseBrace.
+  bool SearchClosingBrace(StringRef OpenBrace, StringRef CloseBrace) {
+    unsigned Depth = 1;
+    P = C;
+    while (P < End) {
+      StringRef S(P, End - P);
+      if (S.startswith(OpenBrace)) {
+        ++Depth;
+        P += OpenBrace.size();
+      } else if (S.startswith(CloseBrace)) {
+        --Depth;
+        if (Depth == 0) {
+          PEnd = P + CloseBrace.size();
+          return true;
+        }
+        P += CloseBrace.size();
+      } else {
+        ++P;
+      }
+    }
+    return false;
+  }
+
   // Advance 1-past previous next/search.
   // Behavior is undefined if previous next/search failed.
   bool Advance() {
@@ -437,7 +461,7 @@ static bool ParseDirective(StringRef S, ExpectedData *ED, SourceManager &SM,
     const char* const ContentBegin = PH.C; // mark content begin
 
     // Search for token: }}
-    if (!PH.Search("}}")) {
+    if (!PH.SearchClosingBrace("{{", "}}")) {
       Diags.Report(Pos.getLocWithOffset(PH.C-PH.Begin),
                    diag::err_verify_missing_end) << KindStr;
       continue;
@@ -459,6 +483,13 @@ static bool ParseDirective(StringRef S, ExpectedData *ED, SourceManager &SM,
     if (Text.empty())
       Text.assign(ContentBegin, ContentEnd);
 
+    // Check that regex directives contain at least one regex.
+    if (RegexKind && Text.find("{{") == StringRef::npos) {
+      Diags.Report(Pos.getLocWithOffset(ContentBegin-PH.Begin),
+                   diag::err_verify_missing_regex) << Text;
+      return false;
+    }
+
     // Construct new directive.
     Directive *D = Directive::create(RegexKind, Pos, ExpectedLoc, Text,
                                      Min, Max);
@@ -820,10 +851,64 @@ void VerifyDiagnosticConsumer::CheckDiagnostics() {
   ED.Notes.clear();
 }
 
+// Add the characters from FixedStr to RegexStr, escaping as needed.  This
+// avoids the need for backslash-escaping in common patterns.
+static void AddFixedStringToRegEx(StringRef FixedStr, std::string &RegexStr) {
+  // FIXME: Expose FileCheck.cpp's Pattern::AddFixedStringToRegEx as a utility
+  // method in RegEx.
+
+  for (unsigned i = 0, e = FixedStr.size(); i != e; ++i) {
+    switch (FixedStr[i]) {
+    // These are the special characters matched in "p_ere_exp".
+    case '(':
+    case ')':
+    case '^':
+    case '$':
+    case '|':
+    case '*':
+    case '+':
+    case '?':
+    case '.':
+    case '[':
+    case '\\':
+    case '{':
+      RegexStr += '\\';
+      // FALL THROUGH.
+    default:
+      RegexStr += FixedStr[i];
+      break;
+    }
+  }
+}
+
 Directive *Directive::create(bool RegexKind, SourceLocation DirectiveLoc,
                              SourceLocation DiagnosticLoc, StringRef Text,
                              unsigned Min, unsigned Max) {
-  if (RegexKind)
-    return new RegexDirective(DirectiveLoc, DiagnosticLoc, Text, Min, Max);
-  return new StandardDirective(DirectiveLoc, DiagnosticLoc, Text, Min, Max);
+  if (!RegexKind)
+    return new StandardDirective(DirectiveLoc, DiagnosticLoc, Text, Min, Max);
+
+  // Parse the directive into a regular expression.
+  std::string RegexStr;
+  StringRef S = Text;
+  while (!S.empty()) {
+    if (S.startswith("{{")) {
+      S = S.drop_front(2);
+      size_t RegexMatchLength = S.find("}}");
+      assert(RegexMatchLength != StringRef::npos);
+      // Append the regex, enclosed in parentheses.
+      RegexStr += "(";
+      RegexStr.append(S.data(), RegexMatchLength);
+      RegexStr += ")";
+      S = S.drop_front(RegexMatchLength + 2);
+    } else {
+      size_t VerbatimMatchLength = S.find("{{");
+      if (VerbatimMatchLength == StringRef::npos)
+        VerbatimMatchLength = S.size();
+      // Escape and append the fixed string.
+      AddFixedStringToRegEx(S.substr(0, VerbatimMatchLength), RegexStr);
+      S = S.drop_front(VerbatimMatchLength);
+    }
+  }
+
+  return new RegexDirective(DirectiveLoc, DiagnosticLoc, Text, Min, Max, RegexStr);
 }