ClangTools: Support loading exported diagnostics

Add a new toolbar button to load diagnostics exported with

   $ clang-tidy -export-fixes=/path/to/file
   $ clazy-standalone -export-fixes=/path/to/file (master version)

Change-Id: I8316fe0706a18222e68220ef4fbfdc7ae8d09804
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangtools/clangtoolslogfilereader.h

@@ -25,6 +25,8 @@
 
 #pragma once
 
+#include <utils/optional.h>
+
 #include "clangtoolsdiagnostic.h"
 
 namespace Utils { class FilePath; }
@@ -34,10 +36,27 @@ namespace Internal {
 
 using AcceptDiagsFromFilePath = std::function<bool(const Utils::FilePath &)>;
 
+// Reads diagnostics generated by "clang -serialize-diagnostics path/to/file"
 Diagnostics readSerializedDiagnostics(const Utils::FilePath &logFilePath,
                                       const Utils::FilePath &mainFilePath,
                                       const AcceptDiagsFromFilePath &acceptFromFilePath,
                                       QString *errorMessage);
 
+// Reads diagnostics generated by "clang-tidy/clazy-standalone -export-fixes=path/to/file"
+Diagnostics readExportedDiagnostics(const Utils::FilePath &logFilePath,
+                                    const AcceptDiagsFromFilePath &acceptFromFilePath,
+                                    QString *errorMessage);
+
+// Exposed for tests
+struct LineColumnInfo {
+    int line = 1; // 1-based
+    int column = 1; // 1-based
+    int lineStartOffset = 0; // for optimiation/caching purposes
+};
+using OptionalLineColumnInfo = Utils::optional<LineColumnInfo>;
+OptionalLineColumnInfo byteOffsetInUtf8TextToLineColumn(const char *text,
+                                                        int offset,
+                                                        int startLine = 1);
+
 } // namespace Internal
 } // namespace ClangTools