[backported/clang-7][libclang] Add PrintingPolicy for pretty printing declarations

-------------------------------------------------------------------------
* Improves pretty printing for Qt Creator's tooltips.
-------------------------------------------------------------------------

Summary:
Introduce clang_getCursorPrettyPrinted() for pretty printing
declarations. Expose also PrintingPolicy, so the user gets more
fine-grained control of the entities being printed.

The already existing clang_getCursorDisplayName() is pretty limited -
for example, it does not handle return types, parameter names or default
arguments for function declarations. Addressing these issues in
clang_getCursorDisplayName() would mean to duplicate existing code
(e.g. clang::DeclPrinter), so rather expose new API to access the
existing functionality.

Reviewed By: jbcoe

Subscribers: cfe-commits

Tags: #clang

Patch by nik (Nikolai Kosjar)

Differential Revision: https://reviews.llvm.org/D39903

Change-Id: I509a01bb5a1e4e1d899c2725f50ed78e482c075f
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

3 files changed, 294 insertions, 6 deletions

diff --git a/tools/c-index-test/c-index-test.c b/tools/c-index-test/c-index-test.c
index c5e345ef6a..e9902efffb 100644
--- a/tools/c-index-test/c-index-test.c
+++ b/tools/c-index-test/c-index-test.c
@@ -86,6 +86,69 @@ static unsigned getDefaultParsingOptions() {
   return options;
 }
 
+static void ModifyPrintingPolicyAccordingToEnv(CXPrintingPolicy Policy) {
+  struct Mapping {
+    const char *name;
+    enum CXPrintingPolicyProperty property;
+  };
+  struct Mapping mappings[] = {
+      {"CINDEXTEST_PRINTINGPOLICY_INDENTATION", CXPrintingPolicy_Indentation},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSSPECIFIERS",
+       CXPrintingPolicy_SuppressSpecifiers},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSTAGKEYWORD",
+       CXPrintingPolicy_SuppressTagKeyword},
+      {"CINDEXTEST_PRINTINGPOLICY_INCLUDETAGDEFINITION",
+       CXPrintingPolicy_IncludeTagDefinition},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSSCOPE",
+       CXPrintingPolicy_SuppressScope},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSUNWRITTENSCOPE",
+       CXPrintingPolicy_SuppressUnwrittenScope},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSINITIALIZERS",
+       CXPrintingPolicy_SuppressInitializers},
+      {"CINDEXTEST_PRINTINGPOLICY_CONSTANTARRAYSIZEASWRITTEN",
+       CXPrintingPolicy_ConstantArraySizeAsWritten},
+      {"CINDEXTEST_PRINTINGPOLICY_ANONYMOUSTAGLOCATIONS",
+       CXPrintingPolicy_AnonymousTagLocations},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSSTRONGLIFETIME",
+       CXPrintingPolicy_SuppressStrongLifetime},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSLIFETIMEQUALIFIERS",
+       CXPrintingPolicy_SuppressLifetimeQualifiers},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSTEMPLATEARGSINCXXCONSTRUCTORS",
+       CXPrintingPolicy_SuppressTemplateArgsInCXXConstructors},
+      {"CINDEXTEST_PRINTINGPOLICY_BOOL", CXPrintingPolicy_Bool},
+      {"CINDEXTEST_PRINTINGPOLICY_RESTRICT", CXPrintingPolicy_Restrict},
+      {"CINDEXTEST_PRINTINGPOLICY_ALIGNOF", CXPrintingPolicy_Alignof},
+      {"CINDEXTEST_PRINTINGPOLICY_UNDERSCOREALIGNOF",
+       CXPrintingPolicy_UnderscoreAlignof},
+      {"CINDEXTEST_PRINTINGPOLICY_USEVOIDFORZEROPARAMS",
+       CXPrintingPolicy_UseVoidForZeroParams},
+      {"CINDEXTEST_PRINTINGPOLICY_TERSEOUTPUT", CXPrintingPolicy_TerseOutput},
+      {"CINDEXTEST_PRINTINGPOLICY_POLISHFORDECLARATION",
+       CXPrintingPolicy_PolishForDeclaration},
+      {"CINDEXTEST_PRINTINGPOLICY_HALF", CXPrintingPolicy_Half},
+      {"CINDEXTEST_PRINTINGPOLICY_MSWCHAR", CXPrintingPolicy_MSWChar},
+      {"CINDEXTEST_PRINTINGPOLICY_INCLUDENEWLINES",
+       CXPrintingPolicy_IncludeNewlines},
+      {"CINDEXTEST_PRINTINGPOLICY_MSVCFORMATTING",
+       CXPrintingPolicy_MSVCFormatting},
+      {"CINDEXTEST_PRINTINGPOLICY_CONSTANTSASWRITTEN",
+       CXPrintingPolicy_ConstantsAsWritten},
+      {"CINDEXTEST_PRINTINGPOLICY_SUPPRESSIMPLICITBASE",
+       CXPrintingPolicy_SuppressImplicitBase},
+      {"CINDEXTEST_PRINTINGPOLICY_FULLYQUALIFIEDNAME",
+       CXPrintingPolicy_FullyQualifiedName},
+  };
+
+  unsigned i;
+  for (i = 0; i < sizeof(mappings) / sizeof(struct Mapping); i++) {
+    char *value = getenv(mappings[i].name);
+    if (value) {
+      clang_PrintingPolicy_setProperty(Policy, mappings[i].property,
+                                       (unsigned)strtoul(value, 0L, 10));
+    }
+  }
+}
+
 /** \brief Returns 0 in case of success, non-zero in case of a failure. */
 static int checkForErrors(CXTranslationUnit TU);
 
@@ -356,7 +419,11 @@ static void PrintRange(CXSourceRange R, const char *str) {
   PrintExtent(stdout, begin_line, begin_column, end_line, end_column);
 }
 
-int want_display_name = 0;
+static enum DisplayType {
+    DisplayType_Spelling,
+    DisplayType_DisplayName,
+    DisplayType_Pretty
+} wanted_display_type = DisplayType_Spelling;
 
 static void printVersion(const char *Prefix, CXVersion Version) {
   if (Version.Major < 0)
@@ -656,6 +723,24 @@ static int lineCol_cmp(const void *p1, const void *p2) {
   return (int)lhs->col - (int)rhs->col;
 }
 
+static CXString CursorToText(CXCursor Cursor) {
+  switch (wanted_display_type) {
+  case DisplayType_Spelling:
+    return clang_getCursorSpelling(Cursor);
+  case DisplayType_DisplayName:
+    return clang_getCursorDisplayName(Cursor);
+  case DisplayType_Pretty:
+  default: {
+    CXString text;
+    CXPrintingPolicy Policy = clang_getCursorPrintingPolicy(Cursor);
+    ModifyPrintingPolicyAccordingToEnv(Policy);
+    text = clang_getCursorPrettyPrinted(Cursor, Policy);
+    clang_PrintingPolicy_dispose(Policy);
+    return text;
+  }
+  }
+}
+
 static void PrintCursor(CXCursor Cursor, const char *CommentSchemaFile) {
   CXTranslationUnit TU = clang_Cursor_getTranslationUnit(Cursor);
   if (clang_isInvalid(Cursor.kind)) {
@@ -682,8 +767,7 @@ static void PrintCursor(CXCursor Cursor, const char *CommentSchemaFile) {
     int I;
 
     ks = clang_getCursorKindSpelling(Cursor.kind);
-    string = want_display_name? clang_getCursorDisplayName(Cursor) 
-                              : clang_getCursorSpelling(Cursor);
+    string = CursorToText(Cursor);
     printf("%s=%s", clang_getCString(ks),
                     clang_getCString(string));
     clang_disposeString(ks);
@@ -1686,7 +1770,12 @@ static int perform_test_load(CXIndex Idx, CXTranslationUnit TU,
     else if (!strcmp(filter, "all-display") || 
              !strcmp(filter, "local-display")) {
       ck = NULL;
-      want_display_name = 1;
+      wanted_display_type = DisplayType_DisplayName;
+    }
+    else if (!strcmp(filter, "all-pretty") ||
+             !strcmp(filter, "local-pretty")) {
+      ck = NULL;
+      wanted_display_type = DisplayType_Pretty;
     }
     else if (!strcmp(filter, "none")) K = (enum CXCursorKind) ~0;
     else if (!strcmp(filter, "category")) K = CXCursor_ObjCCategoryDecl;
@@ -1754,8 +1843,11 @@ int perform_test_load_source(int argc, const char **argv,
   const char *InvocationPath;
 
   Idx = clang_createIndex(/* excludeDeclsFromPCH */
-                          (!strcmp(filter, "local") || 
-                           !strcmp(filter, "local-display"))? 1 : 0,
+                          (!strcmp(filter, "local") ||
+                           !strcmp(filter, "local-display") ||
+                           !strcmp(filter, "local-pretty"))
+                              ? 1
+                              : 0,
                           /* displayDiagnostics=*/1);
   InvocationPath = getenv("CINDEXTEST_INVOCATION_EMISSION_PATH");
   if (InvocationPath)
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 429fca3474..bd2e4bc8d2 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -4706,6 +4706,197 @@ CXStringSet *clang_Cursor_getObjCManglings(CXCursor C) {
   return cxstring::createSet(Manglings);
 }
 
+CXPrintingPolicy clang_getCursorPrintingPolicy(CXCursor C) {
+  if (clang_Cursor_isNull(C))
+    return 0;
+  return new PrintingPolicy(getCursorContext(C).getPrintingPolicy());
+}
+
+void clang_PrintingPolicy_dispose(CXPrintingPolicy Policy) {
+  if (Policy)
+    delete static_cast<PrintingPolicy *>(Policy);
+}
+
+unsigned
+clang_PrintingPolicy_getProperty(CXPrintingPolicy Policy,
+                                 enum CXPrintingPolicyProperty Property) {
+  if (!Policy)
+    return 0;
+
+  PrintingPolicy *P = static_cast<PrintingPolicy *>(Policy);
+  switch (Property) {
+  case CXPrintingPolicy_Indentation:
+    return P->Indentation;
+  case CXPrintingPolicy_SuppressSpecifiers:
+    return P->SuppressSpecifiers;
+  case CXPrintingPolicy_SuppressTagKeyword:
+    return P->SuppressTagKeyword;
+  case CXPrintingPolicy_IncludeTagDefinition:
+    return P->IncludeTagDefinition;
+  case CXPrintingPolicy_SuppressScope:
+    return P->SuppressScope;
+  case CXPrintingPolicy_SuppressUnwrittenScope:
+    return P->SuppressUnwrittenScope;
+  case CXPrintingPolicy_SuppressInitializers:
+    return P->SuppressInitializers;
+  case CXPrintingPolicy_ConstantArraySizeAsWritten:
+    return P->ConstantArraySizeAsWritten;
+  case CXPrintingPolicy_AnonymousTagLocations:
+    return P->AnonymousTagLocations;
+  case CXPrintingPolicy_SuppressStrongLifetime:
+    return P->SuppressStrongLifetime;
+  case CXPrintingPolicy_SuppressLifetimeQualifiers:
+    return P->SuppressLifetimeQualifiers;
+  case CXPrintingPolicy_SuppressTemplateArgsInCXXConstructors:
+    return P->SuppressTemplateArgsInCXXConstructors;
+  case CXPrintingPolicy_Bool:
+    return P->Bool;
+  case CXPrintingPolicy_Restrict:
+    return P->Restrict;
+  case CXPrintingPolicy_Alignof:
+    return P->Alignof;
+  case CXPrintingPolicy_UnderscoreAlignof:
+    return P->UnderscoreAlignof;
+  case CXPrintingPolicy_UseVoidForZeroParams:
+    return P->UseVoidForZeroParams;
+  case CXPrintingPolicy_TerseOutput:
+    return P->TerseOutput;
+  case CXPrintingPolicy_PolishForDeclaration:
+    return P->PolishForDeclaration;
+  case CXPrintingPolicy_Half:
+    return P->Half;
+  case CXPrintingPolicy_MSWChar:
+    return P->MSWChar;
+  case CXPrintingPolicy_IncludeNewlines:
+    return P->IncludeNewlines;
+  case CXPrintingPolicy_MSVCFormatting:
+    return P->MSVCFormatting;
+  case CXPrintingPolicy_ConstantsAsWritten:
+    // Ops, not yet there in clang 5.0 and we do not need it.
+    return 0;
+  case CXPrintingPolicy_SuppressImplicitBase:
+    // Ops, not yet there in clang 5.0 and we do not need it.
+    return 0;
+  case CXPrintingPolicy_FullyQualifiedName:
+    return P->FullyQualifiedName;
+  }
+
+  assert(false && "Invalid CXPrintingPolicyProperty");
+  return 0;
+}
+
+void clang_PrintingPolicy_setProperty(CXPrintingPolicy Policy,
+                                      enum CXPrintingPolicyProperty Property,
+                                      unsigned Value) {
+  if (!Policy)
+    return;
+
+  PrintingPolicy *P = static_cast<PrintingPolicy *>(Policy);
+  switch (Property) {
+  case CXPrintingPolicy_Indentation:
+    P->Indentation = Value;
+    return;
+  case CXPrintingPolicy_SuppressSpecifiers:
+    P->SuppressSpecifiers = Value;
+    return;
+  case CXPrintingPolicy_SuppressTagKeyword:
+    P->SuppressTagKeyword = Value;
+    return;
+  case CXPrintingPolicy_IncludeTagDefinition:
+    P->IncludeTagDefinition = Value;
+    return;
+  case CXPrintingPolicy_SuppressScope:
+    P->SuppressScope = Value;
+    return;
+  case CXPrintingPolicy_SuppressUnwrittenScope:
+    P->SuppressUnwrittenScope = Value;
+    return;
+  case CXPrintingPolicy_SuppressInitializers:
+    P->SuppressInitializers = Value;
+    return;
+  case CXPrintingPolicy_ConstantArraySizeAsWritten:
+    P->ConstantArraySizeAsWritten = Value;
+    return;
+  case CXPrintingPolicy_AnonymousTagLocations:
+    P->AnonymousTagLocations = Value;
+    return;
+  case CXPrintingPolicy_SuppressStrongLifetime:
+    P->SuppressStrongLifetime = Value;
+    return;
+  case CXPrintingPolicy_SuppressLifetimeQualifiers:
+    P->SuppressLifetimeQualifiers = Value;
+    return;
+  case CXPrintingPolicy_SuppressTemplateArgsInCXXConstructors:
+    P->SuppressTemplateArgsInCXXConstructors = Value;
+    return;
+  case CXPrintingPolicy_Bool:
+    P->Bool = Value;
+    return;
+  case CXPrintingPolicy_Restrict:
+    P->Restrict = Value;
+    return;
+  case CXPrintingPolicy_Alignof:
+    P->Alignof = Value;
+    return;
+  case CXPrintingPolicy_UnderscoreAlignof:
+    P->UnderscoreAlignof = Value;
+    return;
+  case CXPrintingPolicy_UseVoidForZeroParams:
+    P->UseVoidForZeroParams = Value;
+    return;
+  case CXPrintingPolicy_TerseOutput:
+    P->TerseOutput = Value;
+    return;
+  case CXPrintingPolicy_PolishForDeclaration:
+    P->PolishForDeclaration = Value;
+    return;
+  case CXPrintingPolicy_Half:
+    P->Half = Value;
+    return;
+  case CXPrintingPolicy_MSWChar:
+    P->MSWChar = Value;
+    return;
+  case CXPrintingPolicy_IncludeNewlines:
+    P->IncludeNewlines = Value;
+    return;
+  case CXPrintingPolicy_MSVCFormatting:
+    P->MSVCFormatting = Value;
+    return;
+  case CXPrintingPolicy_ConstantsAsWritten:
+    // Ops, not yet there in clang 5.0 and we do not need it.
+    return;
+  case CXPrintingPolicy_SuppressImplicitBase:
+    // Ops, not yet there in clang 5.0 and we do not need it.
+    return;
+  case CXPrintingPolicy_FullyQualifiedName:
+    P->FullyQualifiedName = Value;
+    return;
+  }
+
+  assert(false && "Invalid CXPrintingPolicyProperty");
+}
+
+CXString clang_getCursorPrettyPrinted(CXCursor C, CXPrintingPolicy cxPolicy) {
+  if (clang_Cursor_isNull(C))
+    return cxstring::createEmpty();
+
+  if (clang_isDeclaration(C.kind)) {
+    const Decl *D = getCursorDecl(C);
+    if (!D)
+      return cxstring::createEmpty();
+
+    SmallString<128> Str;
+    llvm::raw_svector_ostream OS(Str);
+    PrintingPolicy *UserPolicy = static_cast<PrintingPolicy *>(cxPolicy);
+    D->print(OS, UserPolicy ? *UserPolicy
+                            : getCursorContext(C).getPrintingPolicy());
+
+    return cxstring::createDup(OS.str());
+  }
+
+  return cxstring::createEmpty();
+}
+
 CXString clang_getCursorDisplayName(CXCursor C) {
   if (!clang_isDeclaration(C.kind))
     return clang_getCursorSpelling(C);
diff --git a/tools/libclang/libclang.exports b/tools/libclang/libclang.exports
index 5d1b0224ef..67e4b4334b 100644
--- a/tools/libclang/libclang.exports
+++ b/tools/libclang/libclang.exports
@@ -178,6 +178,8 @@ clang_getCursorAvailability
 clang_getCursorCompletionString
 clang_getCursorDefinition
 clang_getCursorDisplayName
+clang_getCursorPrintingPolicy
+clang_getCursorPrettyPrinted
 clang_getCursorExtent
 clang_getCursorExceptionSpecificationType
 clang_getCursorKind
@@ -359,3 +361,6 @@ clang_EvalResult_isUnsignedInt
 clang_EvalResult_getAsDouble
 clang_EvalResult_getAsStr
 clang_EvalResult_dispose
+clang_PrintingPolicy_getProperty
+clang_PrintingPolicy_setProperty
+clang_PrintingPolicy_dispose