[Serialized diagnostics] Encode category documentation URL in existing record

clang/include/clang-c/CXDiagnostic.h

@@ -338,6 +338,14 @@ clang_getDiagnosticCategoryName(unsigned Category);
  */
 CINDEX_LINKAGE CXString clang_getDiagnosticCategoryText(CXDiagnostic);
 
+/**
+ * Retrieve the diagnostic category's URL for a given diagnostic.
+ *
+ * \returns The URL that provides additional documentation for the
+ * category of this diagnostic.
+ */
+CINDEX_LINKAGE CXString clang_getDiagnosticCategoryURL(CXDiagnostic);
+
 /**
  * Determine the number of source ranges associated with the given
  * diagnostic.

clang/include/clang/Frontend/SerializedDiagnosticReader.h

@@ -89,10 +89,21 @@ class SerializedDiagnosticReader {
   virtual std::error_code visitEndOfDiagnostic() { return {}; }
 
   /// Visit a category. This associates the category \c ID to a \c Name.
+  ///
+  /// This entrypoint has been superseded by the overload that follows, which
+  /// also takes a (possibly-empty) URL providing additional documentation for
+  /// the category.
   virtual std::error_code visitCategoryRecord(unsigned ID, StringRef Name) {
     return {};
   }
 
+  /// Visit a category. This associates the category \c ID to a \c Name with
+  /// a (possibly empty) URL.
+  virtual std::error_code visitCategoryRecord(unsigned ID, StringRef Name,
+                                              StringRef URL) {
+    return visitCategoryRecord(ID, Name);
+  }
+
   /// Visit a flag. This associates the flag's \c ID to a \c Name.
   virtual std::error_code visitDiagFlagRecord(unsigned ID, StringRef Name) {
     return {};

clang/lib/Frontend/SerializedDiagnosticReader.cpp

@@ -266,13 +266,28 @@ SerializedDiagnosticReader::readDiagnosticBlock(llvm::BitstreamCursor &Stream) {
       continue;
 
     switch ((RecordIDs)RecID) {
-    case RECORD_CATEGORY:
+    case RECORD_CATEGORY: {
       // A category has ID and name size.
       if (Record.size() != 2)
         return SDError::MalformedDiagnosticRecord;
-      if ((EC = visitCategoryRecord(Record[0], Blob)))
+
+      // Make sure the name size makes sense.
+      unsigned NameLen = Record[1];
+      if (NameLen > Blob.size())
+        return SDError::MalformedDiagnosticRecord;
+
+      StringRef Name = Blob.substr(0, NameLen);
+      StringRef URL;
+
+      // If the name didn't take up the full blob, and the character that
+      // follows it is an '@', the rest is the category URL.
+      if (NameLen < Blob.size() && Blob[NameLen] == '@')
+        URL = Blob.substr(NameLen + 1);
+
+      if ((EC = visitCategoryRecord(Record[0], Name, URL)))
         return EC;
       continue;
+    }
     case RECORD_DIAG:
       // A diagnostic has severity, location (4), category, flag, and message
       // size.

clang/tools/c-index-test/c-index-test.c

@@ -4803,9 +4803,10 @@ static void printDiagnosticSet(
     CXSourceLocation DiagLoc;
     CXDiagnostic D;
     CXFile File;
-    CXString FileName, DiagSpelling, DiagOption, DiagCat;
+    CXString FileName, DiagSpelling, DiagOption, DiagCat, DiagCatURL;
     unsigned line, column, offset;
-    const char *FileNameStr = 0, *DiagOptionStr = 0, *DiagCatStr = 0;
+    const char *FileNameStr = 0, *DiagOptionStr = 0, *DiagCatStr = 0,
+      *DiagCatURLStr = 0;
     const char *FileContents = 0;
 
     D = clang_getDiagnosticInSet(Diags, i);
@@ -4863,13 +4864,20 @@ static void printDiagnosticSet(
       fprintf(stderr, "%s\nEND CONTENTS OF FILE\n", FileContents);
     }
 
+    DiagCatURL = clang_getDiagnosticCategoryURL(D);
+    DiagCatURLStr = clang_getCString(DiagCatURL);
+    if (DiagCatURLStr && DiagCatStr && DiagCatURLStr[0]) {
+      fprintf(stderr, "[%s]: <%s>\n", DiagCatStr, DiagCatURLStr);
+    }
+
     /* Print subdiagnostics. */
     printDiagnosticSet(clang_getChildDiagnostics(D), indent+2, TopDiags);
 
     clang_disposeString(FileName);
     clang_disposeString(DiagSpelling);
     clang_disposeString(DiagOption);
     clang_disposeString(DiagCat);
+    clang_disposeString(DiagCatURL);
   }
 }
 

clang/tools/libclang/CIndexDiagnostic.cpp

@@ -70,6 +70,7 @@ class CXDiagnosticCustomNoteImpl : public CXDiagnosticImpl {
 
   unsigned getCategory() const override { return 0; }
   CXString getCategoryText() const override { return cxstring::createEmpty(); }
+  CXString getCategoryURL() const override { return cxstring::createEmpty(); }
 
   unsigned getNumRanges() const override { return 0; }
   CXSourceRange getRange(unsigned Range) const override {
@@ -430,7 +431,13 @@ CXString clang_getDiagnosticCategoryText(CXDiagnostic Diag) {
     return D->getCategoryText();
   return cxstring::createEmpty();
 }
-
+
+CXString clang_getDiagnosticCategoryURL(CXDiagnostic Diag) {
+  if (CXDiagnosticImpl *D = static_cast<CXDiagnosticImpl *>(Diag))
+    return D->getCategoryURL();
+  return cxstring::createEmpty();
+}
+
 unsigned clang_getDiagnosticNumRanges(CXDiagnostic Diag) {
   if (CXDiagnosticImpl *D = static_cast<CXDiagnosticImpl *>(Diag))
     return D->getNumRanges();

clang/tools/libclang/CIndexDiagnostic.h

@@ -99,6 +99,9 @@ class CXDiagnosticImpl {
   /// Return the category string of the diagnostic.
   virtual CXString getCategoryText() const = 0;
 
+  /// Return the category URL of the diagnostic.
+  virtual CXString getCategoryURL() const = 0;
+
   /// Return the number of source ranges for the diagnostic.
   virtual unsigned getNumRanges() const = 0;
 
@@ -160,6 +163,9 @@ struct CXStoredDiagnostic : public CXDiagnosticImpl {
   /// Return the category string of the diagnostic.
   CXString getCategoryText() const override;
 
+  /// Return the category URL of the diagnostic.
+  CXString getCategoryURL() const override;
+
   /// Return the number of source ranges for the diagnostic.
   unsigned getNumRanges() const override;
 

clang/tools/libclang/CXLoadedDiagnostic.cpp

@@ -41,6 +41,7 @@ class CXLoadedDiagnosticSetImpl : public CXDiagnosticSetImpl {
 
   llvm::BumpPtrAllocator Alloc;
   Strings Categories;
+  Strings CategoryURLs;
   Strings WarningFlags;
   Strings FileNames;
 
@@ -126,6 +127,10 @@ CXString CXLoadedDiagnostic::getCategoryText() const {
   return cxstring::createDup(CategoryText);
 }
 
+CXString CXLoadedDiagnostic::getCategoryURL() const {
+  return cxstring::createDup(CategoryURL);
+}
+
 unsigned CXLoadedDiagnostic::getNumRanges() const {
   return Ranges.size();
 }
@@ -215,7 +220,8 @@ class DiagLoader : serialized_diags::SerializedDiagnosticReader {
   std::error_code visitStartOfDiagnostic() override;
   std::error_code visitEndOfDiagnostic() override;
 
-  std::error_code visitCategoryRecord(unsigned ID, StringRef Name) override;
+  std::error_code visitCategoryRecord(unsigned ID, StringRef Name,
+                                      StringRef URL) override;
 
   std::error_code visitDiagFlagRecord(unsigned ID, StringRef Name) override;
 
@@ -345,11 +351,13 @@ std::error_code DiagLoader::visitEndOfDiagnostic() {
   return std::error_code();
 }
 
-std::error_code DiagLoader::visitCategoryRecord(unsigned ID, StringRef Name) {
+std::error_code DiagLoader::visitCategoryRecord(unsigned ID, StringRef Name,
+                                                StringRef URL) {
   // FIXME: Why do we care about long strings?
   if (Name.size() > 65536)
     return reportInvalidFile("Out-of-bounds string in category");
   TopDiags->Categories[ID] = TopDiags->copyString(Name);
+  TopDiags->CategoryURLs[ID] = TopDiags->copyString(URL);
   return std::error_code();
 }
 
@@ -431,6 +439,7 @@ std::error_code DiagLoader::visitDiagnosticRecord(
   D.category = Category;
   D.DiagOption = Flag ? TopDiags->WarningFlags[Flag] : "";
   D.CategoryText = Category ? TopDiags->Categories[Category] : "";
+  D.CategoryURL = Category ? TopDiags->CategoryURLs[Category] : "";
   D.Spelling = TopDiags->copyString(Message);
   return std::error_code();
 }

clang/tools/libclang/CXLoadedDiagnostic.h

@@ -49,6 +49,9 @@ class CXLoadedDiagnostic : public CXDiagnosticImpl {
   /// Return the category string of the diagnostic.
   CXString getCategoryText() const override;
 
+  /// Return the category URL of the diagnostic.
+  CXString getCategoryURL() const override;
+
   /// Return the number of source ranges for the diagnostic.
   unsigned getNumRanges() const override;
 
@@ -89,6 +92,7 @@ class CXLoadedDiagnostic : public CXDiagnosticImpl {
   const char *Spelling;
   llvm::StringRef DiagOption;
   llvm::StringRef CategoryText;
+  llvm::StringRef CategoryURL;
   unsigned severity;
   unsigned category;
 };

clang/tools/libclang/CXStoredDiagnostic.cpp

@@ -76,6 +76,11 @@ CXString CXStoredDiagnostic::getCategoryText() const {
   return cxstring::createRef(DiagnosticIDs::getCategoryNameFromID(catID));
 }
 
+CXString CXStoredDiagnostic::getCategoryURL() const {
+  // Clang does not currently provide URLs for its own diagnostics.
+  return cxstring::createEmpty();
+}
+
 unsigned CXStoredDiagnostic::getNumRanges() const {
   if (Diag.getLocation().isInvalid())
     return 0;

clang/tools/libclang/libclang.map

@@ -344,6 +344,7 @@ LLVM_13 {
     clang_getDiagnosticCategory;
     clang_getDiagnosticCategoryName;
     clang_getDiagnosticCategoryText;
+    clang_getDiagnosticCategoryURL;
     clang_getDiagnosticFixIt;
     clang_getDiagnosticInSet;
     clang_getDiagnosticLocation;