Optionally demote fatal errors to non-fatal errors.

This behavior is enabled when the new CXTranslationUnit_KeepGoing
option is passed to clang_parseTranslationUnit{,2}. It is geared
towards use by IDEs and similar consumers of the clang-c API where
fatal errors may arise when parsing incomplete code mid-edit, or
when include paths are not properly configured yet. In such situations
one still wants to get as much information as possible about a TU.
Previously, the semantic analysis would not instantiate templates
or report additional fatal errors after the first fatal error was
encountered.

Fixes PR24268.

Patch by Milian Wolff.

llvm-svn: 262318

2 files changed, 7 insertions, 0 deletions

diff --git a/clang/lib/Basic/Diagnostic.cpp b/clang/lib/Basic/Diagnostic.cpp
index 7cf7305827f..f10d156743b 100644
--- a/clang/lib/Basic/Diagnostic.cpp
+++ b/clang/lib/Basic/Diagnostic.cpp
@@ -68,6 +68,7 @@ DiagnosticsEngine::DiagnosticsEngine(
   WarningsAsErrors = false;
   EnableAllWarnings = false;
   ErrorsAsFatal = false;
+  FatalsAsError = false;
   SuppressSystemWarnings = false;
   SuppressAllDiagnostics = false;
   ElideType = true;
diff --git a/clang/lib/Basic/DiagnosticIDs.cpp b/clang/lib/Basic/DiagnosticIDs.cpp
index a34c7fecb53..efc3f94c959 100644
--- a/clang/lib/Basic/DiagnosticIDs.cpp
+++ b/clang/lib/Basic/DiagnosticIDs.cpp
@@ -462,6 +462,12 @@ DiagnosticIDs::getDiagnosticSeverity(unsigned DiagID, SourceLocation Loc,
       Result = diag::Severity::Fatal;
   }
 
+  // If explicitly requested, map fatal errors to errors.
+  if (Result == diag::Severity::Fatal) {
+      if (Diag.FatalsAsError)
+        Result = diag::Severity::Error;
+  }
+
   // Custom diagnostics always are emitted in system headers.
   bool ShowInSystemHeader =
       !GetDiagInfo(DiagID) || GetDiagInfo(DiagID)->WarnShowInSystemHeader;