[clang-doc] Support default args for functions.

Adds support for default arguments in the internal representation and reads these values from the source. Implements writing these values to YAML but does not implement this for the HTML or markdown outputs.

Reviewed By: paulkirth

Differential Revision: https://reviews.llvm.org/D133732

8 files changed, 45 insertions, 13 deletions

diff --git a/clang-tools-extra/clang-doc/BitcodeReader.cpp b/clang-tools-extra/clang-doc/BitcodeReader.cpp
index 35e3aef..7736e3d 100644
--- a/clang-tools-extra/clang-doc/BitcodeReader.cpp
+++ b/clang-tools-extra/clang-doc/BitcodeReader.cpp
@@ -259,6 +259,8 @@ llvm::Error parseRecord(const Record &R, unsigned ID, llvm::StringRef Blob,
   switch (ID) {
   case FIELD_TYPE_NAME:
     return decodeRecord(R, I->Name, Blob);
+  case FIELD_DEFAULT_VALUE:
+    return decodeRecord(R, I->DefaultValue, Blob);
   default:
     return llvm::createStringError(llvm::inconvertibleErrorCode(),
                                    "invalid field for TypeInfo");
diff --git a/clang-tools-extra/clang-doc/BitcodeWriter.cpp b/clang-tools-extra/clang-doc/BitcodeWriter.cpp
index 3daeb80..7e23170 100644
--- a/clang-tools-extra/clang-doc/BitcodeWriter.cpp
+++ b/clang-tools-extra/clang-doc/BitcodeWriter.cpp
@@ -148,6 +148,7 @@ static const llvm::IndexedMap<RecordIdDsc, RecordIdToIndexFunctor>
           {COMMENT_ATTRVAL, {"AttrVal", &StringAbbrev}},
           {COMMENT_ARG, {"Arg", &StringAbbrev}},
           {FIELD_TYPE_NAME, {"Name", &StringAbbrev}},
+          {FIELD_DEFAULT_VALUE, {"DefaultValue", &StringAbbrev}},
           {MEMBER_TYPE_NAME, {"Name", &StringAbbrev}},
           {MEMBER_TYPE_ACCESS, {"Access", &IntAbbrev}},
           {NAMESPACE_USR, {"USR", &SymbolIDAbbrev}},
@@ -207,7 +208,7 @@ static const std::vector<std::pair<BlockId, std::vector<RecordId>>>
         // Type Block
         {BI_TYPE_BLOCK_ID, {}},
         // FieldType Block
-        {BI_FIELD_TYPE_BLOCK_ID, {FIELD_TYPE_NAME}},
+        {BI_FIELD_TYPE_BLOCK_ID, {FIELD_TYPE_NAME, FIELD_DEFAULT_VALUE}},
         // MemberType Block
         {BI_MEMBER_TYPE_BLOCK_ID, {MEMBER_TYPE_NAME, MEMBER_TYPE_ACCESS}},
         // Enum Block
@@ -419,6 +420,7 @@ void ClangDocBitcodeWriter::emitBlock(const FieldTypeInfo &T) {
   StreamSubBlockGuard Block(Stream, BI_FIELD_TYPE_BLOCK_ID);
   emitBlock(T.Type, FieldId::F_type);
   emitRecord(T.Name, FIELD_TYPE_NAME);
+  emitRecord(T.DefaultValue, FIELD_DEFAULT_VALUE);
 }
 
 void ClangDocBitcodeWriter::emitBlock(const MemberTypeInfo &T) {
diff --git a/clang-tools-extra/clang-doc/BitcodeWriter.h b/clang-tools-extra/clang-doc/BitcodeWriter.h
index 7deda2e..cc51eb5 100644
--- a/clang-tools-extra/clang-doc/BitcodeWriter.h
+++ b/clang-tools-extra/clang-doc/BitcodeWriter.h
@@ -88,6 +88,7 @@ enum RecordId {
   COMMENT_ATTRVAL,
   COMMENT_ARG,
   FIELD_TYPE_NAME,
+  FIELD_DEFAULT_VALUE,
   MEMBER_TYPE_NAME,
   MEMBER_TYPE_ACCESS,
   NAMESPACE_USR,
diff --git a/clang-tools-extra/clang-doc/Representation.h b/clang-tools-extra/clang-doc/Representation.h
index 2738b6f..65a0ae8 100644
--- a/clang-tools-extra/clang-doc/Representation.h
+++ b/clang-tools-extra/clang-doc/Representation.h
@@ -181,10 +181,15 @@ struct FieldTypeInfo : public TypeInfo {
       : TypeInfo(RefName, Path), Name(Name) {}
 
   bool operator==(const FieldTypeInfo &Other) const {
-    return std::tie(Type, Name) == std::tie(Other.Type, Other.Name);
+    return std::tie(Type, Name, DefaultValue) ==
+           std::tie(Other.Type, Other.Name, Other.DefaultValue);
   }
 
   SmallString<16> Name; // Name associated with this info.
+
+  // When used for function parameters, contains the string representing the
+  // expression of the default value, if any.
+  SmallString<16> DefaultValue;
 };
 
 // Info for member types.
diff --git a/clang-tools-extra/clang-doc/Serialize.cpp b/clang-tools-extra/clang-doc/Serialize.cpp
index 6e6308d..cb1b81d 100644
--- a/clang-tools-extra/clang-doc/Serialize.cpp
+++ b/clang-tools-extra/clang-doc/Serialize.cpp
@@ -10,6 +10,7 @@
 #include "BitcodeWriter.h"
 #include "clang/AST/Comment.h"
 #include "clang/Index/USRGeneration.h"
+#include "clang/Lex/Lexer.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/SHA1.h"
@@ -310,21 +311,31 @@ static void parseEnumerators(EnumInfo &I, const EnumDecl *D) {
 
 static void parseParameters(FunctionInfo &I, const FunctionDecl *D) {
   for (const ParmVarDecl *P : D->parameters()) {
+    FieldTypeInfo *FieldInfo = nullptr;
     if (const auto *T = getDeclForType(P->getOriginalType())) {
       if (const auto *N = dyn_cast<EnumDecl>(T)) {
-        I.Params.emplace_back(getUSRForDecl(N), N->getNameAsString(),
-                              InfoType::IT_enum, getInfoRelativePath(N),
-                              P->getNameAsString());
-        continue;
+        FieldInfo = &I.Params.emplace_back(
+            getUSRForDecl(N), N->getNameAsString(), InfoType::IT_enum,
+            getInfoRelativePath(N), P->getNameAsString());
       } else if (const auto *N = dyn_cast<RecordDecl>(T)) {
-        I.Params.emplace_back(getUSRForDecl(N), N->getNameAsString(),
-                              InfoType::IT_record, getInfoRelativePath(N),
-                              P->getNameAsString());
-        continue;
+        FieldInfo = &I.Params.emplace_back(
+            getUSRForDecl(N), N->getNameAsString(), InfoType::IT_record,
+            getInfoRelativePath(N), P->getNameAsString());
       }
+      // Otherwise fall through to the default case below.
+    }
+
+    if (!FieldInfo) {
+      FieldInfo = &I.Params.emplace_back(P->getOriginalType().getAsString(),
+                                         P->getNameAsString());
+    }
+
+    if (const Expr *DefaultArg = P->getDefaultArg()) {
+      FieldInfo->DefaultValue = Lexer::getSourceText(
+          CharSourceRange::getTokenRange(DefaultArg->getSourceRange()),
+          D->getASTContext().getSourceManager(),
+          D->getASTContext().getLangOpts());
     }
-    I.Params.emplace_back(P->getOriginalType().getAsString(),
-                          P->getNameAsString());
   }
 }
 
diff --git a/clang-tools-extra/clang-doc/YAMLGenerator.cpp b/clang-tools-extra/clang-doc/YAMLGenerator.cpp
index ff7abee..2022e4a 100644
--- a/clang-tools-extra/clang-doc/YAMLGenerator.cpp
+++ b/clang-tools-extra/clang-doc/YAMLGenerator.cpp
@@ -109,6 +109,7 @@ static void TypeInfoMapping(IO &IO, TypeInfo &I) {
 static void FieldTypeInfoMapping(IO &IO, FieldTypeInfo &I) {
   TypeInfoMapping(IO, I);
   IO.mapOptional("Name", I.Name, SmallString<16>());
+  IO.mapOptional("DefaultValue", I.DefaultValue, SmallString<16>());
 }
 
 static void InfoMapping(IO &IO, Info &I) {
@@ -183,6 +184,7 @@ template <> struct MappingTraits<FieldTypeInfo> {
   static void mapping(IO &IO, FieldTypeInfo &I) {
     TypeInfoMapping(IO, I);
     IO.mapOptional("Name", I.Name, SmallString<16>());
+    IO.mapOptional("DefaultValue", I.DefaultValue, SmallString<16>());
   }
 };
 
diff --git a/clang-tools-extra/unittests/clang-doc/SerializeTest.cpp b/clang-tools-extra/unittests/clang-doc/SerializeTest.cpp
index 187ea39..244af56 100644
--- a/clang-tools-extra/unittests/clang-doc/SerializeTest.cpp
+++ b/clang-tools-extra/unittests/clang-doc/SerializeTest.cpp
@@ -511,7 +511,7 @@ TEST(SerializeTest, emitModulePublicLFunctions) {
   std::vector<std::string> Args;
   Args.push_back("-fmodules-ts");
   ExtractInfosFromCodeWithArgs(R"raw(export module M;
-int moduleFunction(int x);
+int moduleFunction(int x, double d = 3.2 - 1.0);
 static int staticModuleFunction(int x);
 export double exportedModuleFunction(double y);)raw",
                                2, /*Public=*/true, Infos, Args);
@@ -523,6 +523,8 @@ export double exportedModuleFunction(double y);)raw",
   F.ReturnType = TypeInfo(EmptySID, "int", InfoType::IT_default);
   F.Loc.emplace_back(0, llvm::SmallString<16>{"test.cpp"});
   F.Params.emplace_back("int", "x");
+  F.Params.emplace_back("double", "d");
+  F.Params.back().DefaultValue = "3.2 - 1.0";
   F.Access = AccessSpecifier::AS_none;
   ExpectedBWithFunction.ChildFunctions.emplace_back(std::move(F));
   CheckNamespaceInfo(&ExpectedBWithFunction, BWithFunction);
diff --git a/clang-tools-extra/unittests/clang-doc/YAMLGeneratorTest.cpp b/clang-tools-extra/unittests/clang-doc/YAMLGeneratorTest.cpp
index ea30bfd..aff52c7 100644
--- a/clang-tools-extra/unittests/clang-doc/YAMLGeneratorTest.cpp
+++ b/clang-tools-extra/unittests/clang-doc/YAMLGeneratorTest.cpp
@@ -209,6 +209,8 @@ TEST(YAMLGeneratorTest, emitFunctionYAML) {
   I.ReturnType =
       TypeInfo(EmptySID, "void", InfoType::IT_default, "path/to/void");
   I.Params.emplace_back("int", "path/to/int", "P");
+  I.Params.emplace_back("double", "path/to/double", "D");
+  I.Params.back().DefaultValue = "2.0 * M_PI";
   I.IsMethod = true;
   I.Parent = Reference(EmptySID, "Parent", InfoType::IT_record);
 
@@ -240,6 +242,11 @@ Params:
       Name:            'int'
       Path:            'path/to/int'
     Name:            'P'
+  - Type:
+      Name:            'double'
+      Path:            'path/to/double'
+    Name:            'D'
+    DefaultValue:    '2.0 * M_PI'
 ReturnType:
   Type:
     Name:            'void'