Add a notion of "post-diagnostic hooks", which are callbacks attached

to a diagnostic that will be invoked after the diagnostic (if it is
not suppressed). The hooks are allowed to produce additional
diagnostics (typically notes) that provide more information. We should
be able to use this to help diagnostic clients link notes back to the
diagnostic they clarify. Comments welcome; I'll write up documentation
and convert other clients (e.g., overload resolution failures) if
there are no screams of protest.

As the first client of post-diagnostic hooks, we now produce a
template instantiation backtrace when a failure occurs during template
instantiation. There's still more work to do to make this output
pretty, if that's even possible.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@66557 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/Basic/Diagnostic.cpp b/lib/Basic/Diagnostic.cpp
index 893eae5d1a..fa5ca57dfe 100644
--- a/lib/Basic/Diagnostic.cpp
+++ b/lib/Basic/Diagnostic.cpp
@@ -201,6 +201,8 @@ Diagnostic::Diagnostic(DiagnosticClient *client) : Client(client) {
   
   ArgToStringFn = DummyArgToStringFn;
   ArgToStringCookie = 0;
+
+  InPostDiagnosticHook = false;
 }
 
 Diagnostic::~Diagnostic() {
@@ -225,6 +227,12 @@ bool Diagnostic::isBuiltinWarningOrExtension(unsigned DiagID) {
   return DiagID < diag::DIAG_UPPER_LIMIT && getBuiltinDiagClass(DiagID) < ERROR;
 }
 
+/// \brief Determine whether the given built-in diagnostic ID is a
+/// Note.
+bool Diagnostic::isBuiltinNote(unsigned DiagID) {
+  return DiagID < diag::DIAG_UPPER_LIMIT && getBuiltinDiagClass(DiagID) == NOTE;
+}
+
 
 /// getDescription - Given a diagnostic ID, return a description of the
 /// issue.
@@ -373,6 +381,16 @@ void Diagnostic::ProcessDiag() {
   // Finally, report it.
   Client->HandleDiagnostic(DiagLevel, Info);
   if (Client->IncludeInDiagnosticCounts()) ++NumDiagnostics;
+
+  // Invoke any post-diagnostic hooks.
+  unsigned LastDiag = CurDiagID;
+  CurDiagID = ~0U;
+  
+  InPostDiagnosticHook = true;
+  for (unsigned Hook = 0; Hook < NumPostDiagnosticHooks; ++Hook)
+    PostDiagnosticHooks[Hook].Hook(LastDiag, 
+                                   PostDiagnosticHooks[Hook].Cookie);
+  InPostDiagnosticHook = false;
 }