Initial frames support

2 files changed, 9 insertions, 3 deletions

diff --git a/src/libutil/error.cc b/src/libutil/error.cc
index 5f86e1e76..cf4f4a56f 100644
--- a/src/libutil/error.cc
+++ b/src/libutil/error.cc
@@ -9,9 +9,9 @@ namespace nix {
 
 const std::string nativeSystem = SYSTEM;
 
-void BaseError::addTrace(std::optional<ErrPos> e, hintformat hint)
+void BaseError::addTrace(std::optional<ErrPos> e, hintformat hint, bool frame)
 {
-    err.traces.push_front(Trace { .pos = e, .hint = hint });
+    err.traces.push_front(Trace { .pos = e, .hint = hint, .frame = frame });
 }
 
 // c++ std::exception descendants must have a 'const char* what()' function.
@@ -382,6 +382,7 @@ std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool s
      *
      */
 
+    bool frameOnly = false;
     if (!einfo.traces.empty()) {
         unsigned int count = 0;
         for (auto iter = einfo.traces.rbegin(); iter != einfo.traces.rend(); ++iter) {
@@ -391,7 +392,11 @@ std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool s
             }
 
             if (iter->hint.str().empty()) continue;
+            if (frameOnly && !iter->frame) continue;
+
             count++;
+            frameOnly = iter->frame;
+
             oss << "\n" << "… " << iter->hint.str() << "\n";
 
             if (iter->pos.has_value() && (*iter->pos)) {
diff --git a/src/libutil/error.hh b/src/libutil/error.hh
index 50335676e..bf99581e2 100644
--- a/src/libutil/error.hh
+++ b/src/libutil/error.hh
@@ -110,6 +110,7 @@ void printAtPos(const ErrPos & pos, std::ostream & out);
 struct Trace {
     std::optional<ErrPos> pos;
     hintformat hint;
+    bool frame;
 };
 
 struct ErrorInfo {
@@ -188,7 +189,7 @@ public:
         addTrace(e, hintfmt(std::string(fs), args...));
     }
 
-    void addTrace(std::optional<ErrPos> e, hintformat hint);
+    void addTrace(std::optional<ErrPos> e, hintformat hint, bool frame = false);
 
     bool hasTrace() const { return !err.traces.empty(); }
 };