addErrorTrace

src/libexpr/eval.cc

@@ -592,19 +592,19 @@ LocalNoInlineNoReturn(void throwUndefinedVarError(const Pos & pos, const char *
     });
 }
 
-LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2))
+LocalNoInline(void addErrorTrace(Error & e, const char * s, const string & s2))
 {
-    e.addPrefix(format(s) % s2);
+    e.addTrace(std::nullopt, hintfmt(s) % s2);
 }
 
-LocalNoInline(void addErrorPrefix(Error & e, const char * s, const ExprLambda & fun, const Pos & pos))
+LocalNoInline(void addErrorTrace(Error & e, const Pos & pos, const char * s, const ExprLambda & fun))
 {
-    e.addPrefix(format(s) % fun.showNamePos() % pos);
+    e.addTrace(pos, hintfmt(s) % fun.showNamePos());
 }
 
-LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2, const Pos & pos))
+LocalNoInline(void addErrorTrace(Error & e, const Pos & pos, const char * s, const string & s2))
 {
-    e.addPrefix(format(s) % s2 % pos);
+    e.addTrace(pos, hintfmt(s) % s2);
 }
 
 
@@ -818,7 +818,7 @@ void EvalState::evalFile(const Path & path_, Value & v)
     try {
         eval(e, v);
     } catch (Error & e) {
-        addErrorPrefix(e, "while evaluating the file '%1%':\n", path2);
+        addErrorTrace(e, "while evaluating the file '%1%':", path2);
         throw;
     }
 
@@ -1068,8 +1068,8 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
 
     } catch (Error & e) {
         if (pos2 && pos2->file != state.sDerivationNix)
-            addErrorPrefix(e, "while evaluating the attribute '%1%' at %2%:\n",
+            addErrorTrace(e, *pos2, "while evaluating the attribute '%1%'",
-                showAttrPath(state, env, attrPath), *pos2);
+                showAttrPath(state, env, attrPath));
         throw;
     }
 
@@ -1241,7 +1241,9 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & po
         try {
             lambda.body->eval(*this, env2, v);
         } catch (Error & e) {
-            addErrorPrefix(e, "while evaluating %1%, called from %2%:\n", lambda, pos);
+            // TODO something different for 'called from' than usual addTrace?
+            // addErrorTrace(e, pos, "while evaluating %1%, called from %2%:", lambda);
+            addErrorTrace(e, pos, "while evaluating %1%:", lambda);
             throw;
         }
     else
@@ -1516,7 +1518,7 @@ void EvalState::forceValueDeep(Value & v)
                 try {
                     recurse(*i.value);
                 } catch (Error & e) {
-                    addErrorPrefix(e, "while evaluating the attribute '%1%' at %2%:\n", i.name, *i.pos);
+                    addErrorTrace(e, *i.pos, "while evaluating the attribute '%1%'", i.name);
                     throw;
                 }
         }

src/libexpr/primops.cc

@@ -471,7 +471,8 @@ static void prim_addErrorContext(EvalState & state, const Pos & pos, Value * * a
         v = *args[1];
     } catch (Error & e) {
         PathSet context;
-        e.addPrefix(format("%1%\n") % state.coerceToString(pos, *args[0], context));
+        // TODO: is this right, include this pos??  Test it.  esp with LOC.
+        e.addTrace(pos, hintfmt("%1%") % state.coerceToString(pos, *args[0], context));
         throw;
     }
 }
@@ -563,7 +564,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     try {
         drvName = state.forceStringNoCtx(*attr->value, pos);
     } catch (Error & e) {
-        e.addPrefix(fmt("while evaluating the derivation attribute 'name' at %1%:\n", posDrvName));
+        e.addTrace(posDrvName, hintfmt("while evaluating the derivation attribute 'name'"));
         throw;
     }
 
@@ -696,8 +697,9 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             }
 
         } catch (Error & e) {
-            e.addPrefix(format("while evaluating the attribute '%1%' of the derivation '%2%' at %3%:\n")
+            e.addTrace(posDrvName, 
-                % key % drvName % posDrvName);
+                hintfmt("while evaluating the attribute '%1%' of the derivation '%2%'",
+                    key, drvName));
             throw;
         }
     }

src/libmain/shared.cc

@@ -323,11 +323,13 @@ int handleExceptions(const string & programName, std::function<void()> fun)
         printError("Try '%1% --help' for more information.", programName);
         return 1;
     } catch (BaseError & e) {
-        if (settings.showTrace && e.prefix() != "")
+        // TODO showTrace as argument, or have calcWhat check settings?
-            printError(e.prefix());
+        // if (settings.showTrace && e.prefix() != "")
+        //     printError(e.prefix());
         logError(e.info());
-        if (e.prefix() != "" && !settings.showTrace)
+        // TODO fix to detect non-empty trace here.
-            printError("(use '--show-trace' to show detailed location information)");
+        // if (e.prefix() != "" && !settings.showTrace)
+        //     printError("(use '--show-trace' to show detailed location information)");
         return e.status;
     } catch (std::bad_alloc & e) {
         printError(error + "out of memory");

src/libutil/error.cc

@@ -12,20 +12,43 @@ const std::string nativeSystem = SYSTEM;
 
 // addPrefix is used for show-trace.  Strings added with addPrefix
 // will print ahead of the error itself.
-BaseError & BaseError::addPrefix(const FormatOrString & fs)
+// BaseError & BaseError::addPrefix(const FormatOrString & fs)
-{
+// {
-    prefix_ = fs.s + prefix_;
+//     prefix_ = fs.s + prefix_;
-    return *this;
+//     return *this;
-}
+// }
+
+// const string & prefix() const
+// {
+//   // build prefix string on demand??
+
+// }
+// ; //  { return prefix_; }
+
 
 // addPrefix is used for show-trace.  Strings added with addPrefix
 // will print ahead of the error itself.
-BaseError & BaseError::addTrace(hintformat hint, ErrPos e)
+BaseError & BaseError::addTrace(std::optional<ErrPos> e, hintformat hint)
 {
     err.traces.push_front(Trace { .pos = e, .hint = hint});
     return *this;
 }
 
+// const string& BaseError::calcTrace() const
+// {
+//     if (trace_.has_value())
+//         return *trace_;
+//     else {
+//         err.name = sname();
+
+//         std::ostringstream oss;
+//         oss << err;
+//         trace_ = oss.str();
+
+//         return *trace_;
+//     }
+// }
+
 // c++ std::exception descendants must have a 'const char* what()' function.
 // This stringifies the error and caches it for use by what(), or similarly by msg().
 const string& BaseError::calcWhat() const
@@ -284,6 +307,22 @@ std::ostream& operator<<(std::ostream &out, const ErrorInfo &einfo)
         nl = true;
     }
 
+    // traces
+    for (auto iter = einfo.traces.begin(); iter != einfo.traces.end(); ++iter)
+    {
+
+        try {
+            auto pos = *iter->pos;
+            out << iter->hint.str() << showErrPos(pos) << std::endl;
+            NixCode nc { .errPos = pos };
+            getCodeLines(nc);
+            printCodeLines(out, prefix, nc);
+        } catch(const std::bad_optional_access& e) {
+            out << iter->hint.str() << std::endl;
+        }
+
+    }
+
     // description
     if (einfo.description != "") {
         if (nl)

src/libutil/error.hh

@@ -94,7 +94,7 @@ struct NixCode {
 };
 
 struct Trace {
-    ErrPos pos;
+    std::optional<ErrPos> pos;
     hintformat hint;
 };
 
@@ -116,9 +116,12 @@ std::ostream& operator<<(std::ostream &out, const ErrorInfo &einfo);
 class BaseError : public std::exception
 {
 protected:
-    string prefix_; // used for location traces etc.
+    // string prefix_; // used for location traces etc.
     mutable ErrorInfo err;
 
+    // mutable std::optional<string> trace_;
+    // const string& calcTrace() const;
+
     mutable std::optional<string> what_;
     const string& calcWhat() const;
 
@@ -164,9 +167,9 @@ public:
 #endif
 
     const string & msg() const { return calcWhat(); }
-    const string & prefix() const { return prefix_; }
+    // const string & trace() const { return calcTrace(); }
-    BaseError & addPrefix(const FormatOrString & fs);
+    // BaseError & addPrefix(const FormatOrString & fs);
-    BaseError & addTrace(ErrPos e, hintformat hint);
+    BaseError & addTrace(std::optional<ErrPos> e, hintformat hint);
 
     const ErrorInfo & info() { calcWhat(); return err; }
 };

src/nix-env/nix-env.cc

@@ -593,7 +593,7 @@ static void upgradeDerivations(Globals & globals,
                 } else newElems.push_back(i);
 
             } catch (Error & e) {
-                e.addPrefix(fmt("while trying to find an upgrade for '%s':\n", i.queryName()));
+                e.addTrace(std::nullopt, hintfmt("while trying to find an upgrade for '%s'", i.queryName()));
                 throw;
             }
         }
@@ -1185,7 +1185,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
         } catch (AssertionError & e) {
             printMsg(lvlTalkative, "skipping derivation named '%1%' which gives an assertion failure", i.queryName());
         } catch (Error & e) {
-            e.addPrefix(fmt("while querying the derivation named '%1%':\n", i.queryName()));
+            e.addTrace(std::nullopt, hintfmt("while querying the derivation named '%1%'", i.queryName()));
             throw;
         }
     }

src/nix/repl.cc

@@ -211,12 +211,14 @@ void NixRepl::mainLoop(const std::vector<std::string> & files)
                 // input without clearing the input so far.
                 continue;
             } else {
-              printMsg(lvlError, error + "%1%%2%", (settings.showTrace ? e.prefix() : ""), e.msg());
+                printMsg(lvlError, e.msg());
             }
         } catch (Error & e) {
-            printMsg(lvlError, error + "%1%%2%", (settings.showTrace ? e.prefix() : ""), e.msg());
+            // printMsg(lvlError, error + "%1%%2%", (settings.showTrace ? e.prefix() : ""), e.msg());
+            printMsg(lvlError, e.msg());
         } catch (Interrupted & e) {
-            printMsg(lvlError, error + "%1%%2%", (settings.showTrace ? e.prefix() : ""), e.msg());
+            // printMsg(lvlError, error + "%1%%2%", (settings.showTrace ? e.prefix() : ""), e.msg());
+            printMsg(lvlError, e.msg());
         }
 
         // We handled the current input fully, so we should clear it

src/nix/search.cc

@@ -216,7 +216,7 @@ struct CmdSearch : SourceExprCommand, MixJSON
             } catch (AssertionError & e) {
             } catch (Error & e) {
                 if (!toplevel) {
-                    e.addPrefix(fmt("While evaluating the attribute '%s':\n", attrPath));
+                    e.addTrace(std::nullopt, hintfmt("While evaluating the attribute '%s'", attrPath));
                     throw;
                 }
             }