C-import: treat import errors as warnings and continue importing

Author: emillaine

src/sema/c-import.cpp

@@ -249,8 +249,8 @@ struct CToCxConverter final : clang::ASTConsumer {
     }
 
     bool HandleTopLevelDecl(clang::DeclGroupRef declGroup) override {
-        try {
-            for (clang::Decl* decl : declGroup) {
+        for (clang::Decl* decl : declGroup) {
+            try {
                 switch (decl->getKind()) {
                 case clang::Decl::Function: {
                     auto functionDecl = toCx(*llvm::cast<clang::FunctionDecl>(decl));
@@ -304,15 +304,18 @@ struct CToCxConverter final : clang::ASTConsumer {
                 default:
                     break;
                 }
-            }
 
-            // Can't throw exceptions through the Clang API as it has exceptions disabled,
-            // so need to handle them here.
-        } catch (const CompileError& error) {
-            error.report();
-        } catch (...) {
-            llvm_unreachable("Unhandled exception");
+                // Can't throw exceptions through the Clang API as it has exceptions disabled,
+                // so need to handle them here.
+            } catch (const CompileError& error) {
+                CompileError augmentedError = error;
+                augmentedError.message.insert(0, "encountered an internal compiler error in C import: ");
+                augmentedError.reportAsWarning();
+            } catch (...) {
+                WARN(Location(), "Unhandled exception in C import");
+            }
         }
+
         return true; // continue parsing
     }
 

src/support/utility.cpp

@@ -82,13 +82,21 @@ CompileError::CompileError(Location location, std::string&& message, std::vector
 : location(location), message(std::move(message)), notes(std::move(notes)) {}
 
 void CompileError::report() const {
-    if (message.empty()) return; // This is a "silent" error, resulting from a previous, reported error.
+    if (message.empty()) return;
 
     StringFormatter s;
     s << message;
     reportError(location, s, notes);
 }
 
+void CompileError::reportAsWarning() const {
+    if (message.empty()) return;
+
+    StringFormatter s;
+    s << message;
+    reportWarning(location, s, notes);
+}
+
 std::optional<std::string> cx::findExternalCCompiler() {
 #ifdef _WIN32
     auto compilers = {"cl.exe", "clang-cl.exe"};
@@ -128,12 +136,16 @@ void cx::reportError(Location location, StringFormatter& message, llvm::ArrayRef
     }
 }
 
-void cx::reportWarning(Location location, StringFormatter& message) {
+void cx::reportWarning(Location location, StringFormatter& message, llvm::ArrayRef<Note> notes) {
     if (disableWarnings) return;
 
     if (warningsAsErrors) {
-        reportError(location, message);
+        reportError(location, message, notes);
     } else {
         printDiagnostic(location, "warning", llvm::raw_ostream::YELLOW, message.str());
+
+        for (auto& note : notes) {
+            printDiagnostic(note.location, "note", llvm::raw_ostream::BLACK, note.message);
+        }
     }
 }

src/support/utility.h

@@ -60,9 +60,10 @@ struct CompileError : std::exception {
     static CompileError dependentError() { return CompileError(Location(), ""); }
     const char* what() const noexcept override { return message.c_str(); }
     void report() const;
+    void reportAsWarning() const;
 
     Location location;
-    std::string message;
+    std::string message; // Empty if this is a silent "dependent error", resulting from a previous, reported error.
     std::vector<Note> notes;
 };
 
@@ -75,7 +76,7 @@ template<typename T> void printColored(const T& text, llvm::raw_ostream::Colors
 void printStackTrace();
 [[noreturn]] void abort(StringFormatter& message);
 void reportError(Location location, StringFormatter& message, llvm::ArrayRef<Note> notes = {});
-void reportWarning(Location location, StringFormatter& message);
+void reportWarning(Location location, StringFormatter& message, llvm::ArrayRef<Note> notes = {});
 
 #define ABORT(args) \
     { \