[libclang] Allow skipping warnings from all included files

------------------------------------------------------------------
 * https://reviews.llvm.org/D48116
------------------------------------------------------------------

Depending on the included files and the used warning flags, e.g. -
Weverything, a huge number of warnings can be reported for included
files. As processing that many diagnostics comes with a performance
impact and not all clients are interested in those diagnostics, add a
flag to skip them.
This is a cherry pick from commit cc84b351940f2aa9177d0cb83e827be06f219d8f

Change-Id: Ia738a9382b43d210046bff68b3be8cb9dd89206f
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

8 files changed, 41 insertions, 1 deletions

diff --git a/include/clang-c/Index.h b/include/clang-c/Index.h
index 65dada38b0..0dce9f2f27 100644
--- a/include/clang-c/Index.h
+++ b/include/clang-c/Index.h
@@ -33,6 +33,7 @@
  */
 #define CINDEX_VERSION_MAJOR 0
 #define CINDEX_VERSION_MINOR 49
+#define CINDEX_VERSION_HAS_SKIPWARNINGSFROMINCLUDEDFILES_BACKPORTED
 
 #define CINDEX_VERSION_ENCODE(major, minor) ( \
       ((major) * 10000)                       \
@@ -1332,7 +1333,17 @@ enum CXTranslationUnit_Flags {
    *
    * The function bodies of the main file are not skipped.
    */
-  CXTranslationUnit_LimitSkipFunctionBodiesToPreamble = 0x800
+  CXTranslationUnit_LimitSkipFunctionBodiesToPreamble = 0x800,
+
+  /**
+   * Used to indicate that non-errors from included files should be ignored.
+   *
+   * If set, clang_getDiagnosticSetFromTU() will not report e.g. warnings from
+   * included files anymore. This speeds up clang_getDiagnosticSetFromTU() for
+   * the case where these warnings are not of interest, as for an IDE for
+   * example, which typically shows only the diagnostics in the main file.
+   */
+  CXTranslationUnit_IgnoreNonErrorsFromIncludedFiles = 0x1000
 };
 
 /**
diff --git a/include/clang/Basic/Diagnostic.h b/include/clang/Basic/Diagnostic.h
index d30ac14e02..89ccb3e0e2 100644
--- a/include/clang/Basic/Diagnostic.h
+++ b/include/clang/Basic/Diagnostic.h
@@ -213,6 +213,9 @@ private:
   // Suppress all diagnostics.
   bool SuppressAllDiagnostics = false;
 
+  // Suppress non-errors from all included files.
+  bool SuppressNonErrorsFromIncludedFiles = false;
+
   // Elide common types of templates.
   bool ElideType = true;
 
@@ -634,6 +637,10 @@ public:
   }
   bool getSuppressAllDiagnostics() const { return SuppressAllDiagnostics; }
 
+  void setSuppressNonErrorsFromIncludedFiles(bool Val = true) {
+    SuppressNonErrorsFromIncludedFiles = Val;
+  }
+
   /// Set type eliding, to skip outputting same types occurring in
   /// template types.
   void setElideType(bool Val = true) { ElideType = Val; }
diff --git a/include/clang/Frontend/ASTUnit.h b/include/clang/Frontend/ASTUnit.h
index a58cf53943..88c8370c24 100644
--- a/include/clang/Frontend/ASTUnit.h
+++ b/include/clang/Frontend/ASTUnit.h
@@ -43,6 +43,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <memory>
+#include <mutex>
 #include <string>
 #include <utility>
 #include <vector>
diff --git a/lib/Basic/DiagnosticIDs.cpp b/lib/Basic/DiagnosticIDs.cpp
index 8f2c3d06a5..c50da06d3b 100644
--- a/lib/Basic/DiagnosticIDs.cpp
+++ b/lib/Basic/DiagnosticIDs.cpp
@@ -477,6 +477,14 @@ DiagnosticIDs::getDiagnosticSeverity(unsigned DiagID, SourceLocation Loc,
       Result = diag::Severity::Fatal;
   }
 
+  // If requested, ignore warnings from all headers.
+  if (Diag.SuppressNonErrorsFromIncludedFiles &&
+      Result <= diag::Severity::Warning && Loc.isValid() &&
+      !Diag.getSourceManager().isInMainFile(
+          Diag.getSourceManager().getExpansionLoc(Loc))) {
+    return diag::Severity::Ignored;
+  }
+
   // Custom diagnostics always are emitted in system headers.
   bool ShowInSystemHeader =
       !GetDiagInfo(DiagID) || GetDiagInfo(DiagID)->WarnShowInSystemHeader;
diff --git a/test/Index/ignore-warnings-from-headers.cpp b/test/Index/ignore-warnings-from-headers.cpp
new file mode 100644
index 0000000000..3b8d765c4a
--- /dev/null
+++ b/test/Index/ignore-warnings-from-headers.cpp
@@ -0,0 +1,7 @@
+#include "ignore-warnings-from-headers.h"
+
+void g(int unusedInMainFile) {}
+
+// RUN: env CINDEXTEST_IGNORE_NONERRORS_FROM_INCLUDED_FILES=1 c-index-test -test-load-source function %s -Wunused-parameter 2>&1 | FileCheck %s
+// CHECK-NOT: warning: unused parameter 'unusedInHeader'
+// CHECK: warning: unused parameter 'unusedInMainFile'
diff --git a/test/Index/ignore-warnings-from-headers.h b/test/Index/ignore-warnings-from-headers.h
new file mode 100644
index 0000000000..84c249a7f5
--- /dev/null
+++ b/test/Index/ignore-warnings-from-headers.h
@@ -0,0 +1 @@
+void f(int unusedInHeader) {}
diff --git a/tools/c-index-test/c-index-test.c b/tools/c-index-test/c-index-test.c
index 70ab11866e..b7f9cdc518 100644
--- a/tools/c-index-test/c-index-test.c
+++ b/tools/c-index-test/c-index-test.c
@@ -84,6 +84,8 @@ static unsigned getDefaultParsingOptions() {
     options |= CXTranslationUnit_KeepGoing;
   if (getenv("CINDEXTEST_LIMIT_SKIP_FUNCTION_BODIES_TO_PREAMBLE"))
     options |= CXTranslationUnit_LimitSkipFunctionBodiesToPreamble;
+  if (getenv("CINDEXTEST_IGNORE_NONERRORS_FROM_INCLUDED_FILES"))
+    options |= CXTranslationUnit_IgnoreNonErrorsFromIncludedFiles;
 
   return options;
 }
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index 58d565fa82..505bd0a02f 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -3399,6 +3399,9 @@ clang_parseTranslationUnit_Impl(CXIndex CIdx, const char *source_filename,
   if (options & CXTranslationUnit_KeepGoing)
     Diags->setSuppressAfterFatalError(false);
 
+  if (options & CXTranslationUnit_IgnoreNonErrorsFromIncludedFiles)
+      Diags->setSuppressNonErrorsFromIncludedFiles(true);
+
   // Recover resources if we crash before exiting this function.
   llvm::CrashRecoveryContextCleanupRegistrar<DiagnosticsEngine,
     llvm::CrashRecoveryContextReleaseRefCleanup<DiagnosticsEngine> >