[diagtool] Add 'show-enabled', which displays which warnings are enabled.

show-enabled uses the command line you give it to build a CompilerInstance,
so any flags you pass will be processed as if running clang proper.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@157842 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Misc/warning-flags-enabled.c b/test/Misc/warning-flags-enabled.c
new file mode 100644
index 0000000..61e115e
--- /dev/null
+++ b/test/Misc/warning-flags-enabled.c
@@ -0,0 +1,27 @@
+// RUN: diagtool show-enabled 2>&1 | FileCheck %s
+//
+// This shows warnings which are on by default.
+// We just check a few to make sure it's doing something sensible.
+//
+// CHECK: warn_condition_is_assignment
+// CHECK: warn_null_arg
+// CHECK: warn_unterminated_string
+
+
+// RUN: diagtool show-enabled -Wno-everything 2>&1 | count 0
+
+
+// RUN: diagtool show-enabled -Wno-everything -Wobjc-root-class 2>&1 | FileCheck -check-prefix CHECK-WARN %s
+// RUN: diagtool show-enabled -Wno-everything -Werror=objc-root-class 2>&1 | FileCheck -check-prefix CHECK-ERROR %s
+// RUN: diagtool show-enabled -Wno-everything -Wfatal-errors=objc-root-class 2>&1 | FileCheck -check-prefix CHECK-FATAL %s
+//
+// CHECK-WARN:  W  warn_objc_root_class_missing [-Wobjc-root-class]
+// CHECK-ERROR: E  warn_objc_root_class_missing [-Wobjc-root-class]
+// CHECK-FATAL: F  warn_objc_root_class_missing [-Wobjc-root-class]
+
+// RUN: diagtool show-enabled --no-flags -Wno-everything -Wobjc-root-class 2>&1 | FileCheck -check-prefix CHECK-NO-FLAGS %s
+//
+// CHECK-NO-FLAGS-NOT: W
+// CHECK-NO-FLAGS-NOT: E
+// CHECK-NO-FLAGS-NOT: F
+// CHECK-NO-FLAGS: warn_objc_root_class_missing [-Wobjc-root-class]
diff --git a/tools/diagtool/CMakeLists.txt b/tools/diagtool/CMakeLists.txt
index f1fd9de..6263cb1 100644
--- a/tools/diagtool/CMakeLists.txt
+++ b/tools/diagtool/CMakeLists.txt
@@ -1,17 +1,21 @@
 set( LLVM_LINK_COMPONENTS
   support
+  ${LLVM_TARGETS_TO_BUILD}
   )
 
 set( LLVM_USED_LIBS
   clangBasic
   clangLex
   clangSema
+  clangFrontend
   )
 
 add_clang_executable(diagtool
   diagtool_main.cpp
   DiagTool.cpp
+  DiagnosticNames.cpp
   ListWarnings.cpp
+  ShowEnabledWarnings.cpp
 )
 
 if(UNIX)
diff --git a/tools/diagtool/DiagnosticNames.cpp b/tools/diagtool/DiagnosticNames.cpp
new file mode 100644
index 0000000..dd86c28
--- /dev/null
+++ b/tools/diagtool/DiagnosticNames.cpp
@@ -0,0 +1,25 @@
+//===- DiagnosticNames.cpp - Defines a table of all builtin diagnostics ----==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DiagnosticNames.h"
+#include "clang/Basic/AllDiagnostics.h"
+
+using namespace clang;
+
+const diagtool::DiagnosticRecord diagtool::BuiltinDiagnostics[] = {
+#define DIAG_NAME_INDEX(ENUM) { #ENUM, diag::ENUM, STR_SIZE(#ENUM, uint8_t) },
+#include "clang/Basic/DiagnosticIndexName.inc"
+#undef DIAG_NAME_INDEX
+  { 0, 0, 0 }
+};
+
+const size_t diagtool::BuiltinDiagnosticsCount =
+  sizeof(diagtool::BuiltinDiagnostics) /
+  sizeof(diagtool::BuiltinDiagnostics[0]) - 1;
+
diff --git a/tools/diagtool/DiagnosticNames.h b/tools/diagtool/DiagnosticNames.h
new file mode 100644
index 0000000..ac1934a
--- /dev/null
+++ b/tools/diagtool/DiagnosticNames.h
@@ -0,0 +1,28 @@
+//===- DiagnosticNames.h - Defines a table of all builtin diagnostics ------==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace diagtool {
+  struct DiagnosticRecord {
+    const char *NameStr;
+    unsigned short DiagID;
+    uint8_t NameLen;
+    
+    llvm::StringRef getName() const {
+      return llvm::StringRef(NameStr, NameLen);
+    }
+  };
+
+  extern const DiagnosticRecord BuiltinDiagnostics[];
+  extern const size_t BuiltinDiagnosticsCount;
+
+} // end namespace diagtool
+
diff --git a/tools/diagtool/ListWarnings.cpp b/tools/diagtool/ListWarnings.cpp
index 2bbeca8..6c59338 100644
--- a/tools/diagtool/ListWarnings.cpp
+++ b/tools/diagtool/ListWarnings.cpp
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "DiagTool.h"
+#include "DiagnosticNames.h"
 #include "clang/Basic/Diagnostic.h"
 #include "llvm/Support/Format.h"
 #include "llvm/ADT/StringMap.h"
@@ -26,28 +27,6 @@
 using namespace clang;
 
 namespace {
-struct StaticDiagNameIndexRec {
-  const char *NameStr;
-  unsigned short DiagID;
-  uint8_t NameLen;
-
-  StringRef getName() const {
-    return StringRef(NameStr, NameLen);
-  }
-};
-}
-
-static const StaticDiagNameIndexRec StaticDiagNameIndex[] = {
-#define DIAG_NAME_INDEX(ENUM) { #ENUM, diag::ENUM, STR_SIZE(#ENUM, uint8_t) },
-#include "clang/Basic/DiagnosticIndexName.inc"
-#undef DIAG_NAME_INDEX
-  { 0, 0, 0 }
-};
-
-static const unsigned StaticDiagNameIndexSize =
-  sizeof(StaticDiagNameIndex)/sizeof(StaticDiagNameIndex[0])-1;
-
-namespace {
 struct Entry {
   llvm::StringRef DiagName;
   llvm::StringRef Flag;
@@ -73,8 +52,8 @@
   std::vector<Entry> Flagged, Unflagged;
   llvm::StringMap<std::vector<unsigned> > flagHistogram;
   
-  for (const StaticDiagNameIndexRec *di = StaticDiagNameIndex, *de = StaticDiagNameIndex + StaticDiagNameIndexSize;
-       di != de; ++di) {
+  for (const diagtool::DiagnosticRecord *di = diagtool::BuiltinDiagnostics,
+       *de = di + diagtool::BuiltinDiagnosticsCount; di != de; ++di) {
     
     unsigned diagID = di->DiagID;
     
diff --git a/tools/diagtool/Makefile b/tools/diagtool/Makefile
index 6e3bcfc..2f9706e 100644
--- a/tools/diagtool/Makefile
+++ b/tools/diagtool/Makefile
@@ -16,9 +16,9 @@
 # Don't install this.
 NO_INSTALL = 1
 
-LINK_COMPONENTS := support
+LINK_COMPONENTS := support $(TARGETS_TO_BUILD)
 
-USEDLIBS = clangBasic.a
+USEDLIBS = clangBasic.a clangFrontend.a
 
 include $(CLANG_LEVEL)/Makefile
 
diff --git a/tools/diagtool/ShowEnabledWarnings.cpp b/tools/diagtool/ShowEnabledWarnings.cpp
new file mode 100644
index 0000000..b220003
--- /dev/null
+++ b/tools/diagtool/ShowEnabledWarnings.cpp
@@ -0,0 +1,146 @@
+//===- ShowEnabledWarnings - diagtool tool for printing enabled flags -----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DiagTool.h"
+#include "DiagnosticNames.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/TextDiagnosticBuffer.h"
+#include "llvm/Support/TargetSelect.h"
+
+DEF_DIAGTOOL("show-enabled",
+             "Show which warnings are enabled for a given command line",
+             ShowEnabledWarnings)
+
+using namespace clang;
+
+namespace {
+  struct PrettyDiag {
+    StringRef Name;
+    StringRef Flag;
+    DiagnosticsEngine::Level Level;
+
+    PrettyDiag(StringRef name, StringRef flag, DiagnosticsEngine::Level level)
+    : Name(name), Flag(flag), Level(level) {}
+
+    bool operator<(const PrettyDiag &x) const { return Name < x.Name; }
+  };
+}
+
+static char getFlagForLevel(DiagnosticsEngine::Level Level) {
+  switch (Level) {
+  case DiagnosticsEngine::Ignored: return ' ';
+  case DiagnosticsEngine::Note:    return '-';
+  case DiagnosticsEngine::Warning: return 'W';
+  case DiagnosticsEngine::Error:   return 'E';
+  case DiagnosticsEngine::Fatal:   return 'F';
+  }
+}
+
+static CompilerInstance *createCompiler(unsigned int argc, char **argv) {
+  // First, build a compiler instance!
+  OwningPtr<CompilerInstance> Clang(new CompilerInstance());
+  IntrusiveRefCntPtr<DiagnosticIDs> DiagIDs(new DiagnosticIDs());
+  
+  // Initialize targets first. This may be necessary if any warnings are
+  // selectively enabled.
+  llvm::InitializeAllTargets();
+  llvm::InitializeAllTargetMCs();
+  llvm::InitializeAllAsmPrinters();
+  llvm::InitializeAllAsmParsers();
+  
+  // Buffer diagnostics from argument parsing so that we can output them using a
+  // well formed diagnostic object.
+  TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
+  DiagnosticsEngine Diags(DiagIDs, DiagsBuffer);
+  
+  bool Success;
+  Success = CompilerInvocation::CreateFromArgs(Clang->getInvocation(),
+                                               argv, argv+argc, Diags);
+  
+  // We are skipping cc1's usual search for a resource directory.
+  // This is not likely to affect warning output.
+  
+  // Create the actual diagnostics engine.
+  Clang->createDiagnostics(argc, argv);
+  if (!Clang->hasDiagnostics())
+    return NULL;
+  
+  // Flush any errors created when initializing everything. This could happen
+  // for invalid command lines, which will probably give non-sensical results.
+  DiagsBuffer->FlushDiagnostics(Clang->getDiagnostics());
+  if (!Success)
+    return NULL;
+
+  return Clang.take();
+}
+
+int ShowEnabledWarnings::run(unsigned int argc, char **argv, raw_ostream &Out) {
+  // First check our one flag (--flags).
+  bool ShouldShowFlags = true;
+  if (argc > 0) {
+    StringRef FirstArg(*argv);
+    if (FirstArg.equals("--no-flags")) {
+      ShouldShowFlags = false;
+      --argc;
+      ++argv;
+    } else if (FirstArg.equals("--flags")) {
+      ShouldShowFlags = true;
+      --argc;
+      ++argv;
+    }
+  }
+
+  // Create the compiler instance.
+  OwningPtr<CompilerInstance> Clang(createCompiler(argc, argv));
+  if (!Clang)
+    return EXIT_FAILURE;
+
+  DiagnosticsEngine &Diags = Clang->getDiagnostics();
+  
+  // Now we have our diagnostics. Iterate through EVERY diagnostic and see
+  // which ones are turned on.
+  // FIXME: It would be very nice to print which flags are turning on which
+  // diagnostics, but this can be done with a diff.
+  std::vector<PrettyDiag> Active;
+
+  for (const diagtool::DiagnosticRecord *I = diagtool::BuiltinDiagnostics,
+       *E = I + diagtool::BuiltinDiagnosticsCount; I != E; ++I) {
+    unsigned DiagID = I->DiagID;
+    
+    if (DiagnosticIDs::isBuiltinNote(DiagID))
+      continue;
+    
+    if (!DiagnosticIDs::isBuiltinWarningOrExtension(DiagID))
+      continue;
+
+    DiagnosticsEngine::Level DiagLevel =
+      Diags.getDiagnosticLevel(DiagID, SourceLocation());
+    if (DiagLevel == DiagnosticsEngine::Ignored)
+      continue;
+
+    StringRef WarningOpt = DiagnosticIDs::getWarningOptionForDiag(DiagID);
+    Active.push_back(PrettyDiag(I->getName(), WarningOpt, DiagLevel));
+  }
+
+  std::sort(Active.begin(), Active.end());
+
+  // Print them all out.
+  for (std::vector<PrettyDiag>::const_iterator I = Active.begin(),
+       E = Active.end(); I != E; ++I) {
+    if (ShouldShowFlags)
+      Out << getFlagForLevel(I->Level) << "  ";
+    Out << I->Name;
+    if (!I->Flag.empty())
+      Out << " [-W" << I->Flag << "]";
+    Out << '\n';
+  }
+
+  return EXIT_SUCCESS;
+}