Provide a hook to customize missing library error handling

Make it possible for lld users to provide a custom script that would help to
find missing libraries. A possible scenario could be:

    % clang /tmp/a.c -fuse-ld=lld -loauth -Wl,--error-handling-script=/tmp/addLibrary.py
    unable to find library -loauth
    looking for relevant packages to provides that library

        liboauth-0.9.7-4.el7.i686
        liboauth-devel-0.9.7-4.el7.i686
        liboauth-0.9.7-4.el7.x86_64
        liboauth-devel-0.9.7-4.el7.x86_64
        pix-1.6.1-3.el7.x86_64

Where addLibrary would be called with the missing library name as first argument
(in that case addLibrary.py oauth)

Differential Revision: https://reviews.llvm.org/D87758

1 files changed, 7 insertions, 0 deletions

diff --git a/lld/include/lld/Common/ErrorHandler.h b/lld/include/lld/Common/ErrorHandler.h
index 79a5940823bd..64f363014400 100644
--- a/lld/include/lld/Common/ErrorHandler.h
+++ b/lld/include/lld/Common/ErrorHandler.h
@@ -89,11 +89,14 @@ extern llvm::raw_ostream *stderrOS;
 llvm::raw_ostream &outs();
 llvm::raw_ostream &errs();
 
+enum class ErrorTag { LibNotFound };
+
 class ErrorHandler {
 public:
   uint64_t errorCount = 0;
   uint64_t errorLimit = 20;
   StringRef errorLimitExceededMsg = "too many errors emitted, stopping now";
+  StringRef errorHandlingScript;
   StringRef logName = "lld";
   bool exitEarly = true;
   bool fatalWarnings = false;
@@ -103,6 +106,7 @@ public:
   std::function<void()> cleanupCallback;
 
   void error(const Twine &msg);
+  void error(const Twine &msg, ErrorTag tag, ArrayRef<StringRef> args);
   LLVM_ATTRIBUTE_NORETURN void fatal(const Twine &msg);
   void log(const Twine &msg);
   void message(const Twine &msg);
@@ -126,6 +130,9 @@ private:
 ErrorHandler &errorHandler();
 
 inline void error(const Twine &msg) { errorHandler().error(msg); }
+inline void error(const Twine &msg, ErrorTag tag, ArrayRef<StringRef> args) {
+  errorHandler().error(msg, tag, args);
+}
 inline LLVM_ATTRIBUTE_NORETURN void fatal(const Twine &msg) {
   errorHandler().fatal(msg);
 }