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Improve error formatting

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Changes:

* The divider lines are gone. These were in practice a bit confusing,
  in particular with --show-trace or --keep-going, since then there
  were multiple lines, suggesting a start/end which wasn't the case.

* Instead, multi-line error messages are now indented to align with
  the prefix (e.g. "error: ").

* The 'description' field is gone since we weren't really using it.

* 'hint' is renamed to 'msg' since it really wasn't a hint.

* The error is now printed *before* the location info.

* The 'name' field is no longer printed since most of the time it
  wasn't very useful since it was just the name of the exception (like
  EvalError). Ideally in the future this would be a unique, easily
  googleable error ID (like rustc).

* "trace:" is now just "…". This assumes error contexts start with
  something like "while doing X".

Example before:

  error: --- AssertionError ---------------------------------------------------------------------------------------- nix
  at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix

       6|
       7|   x = assert false; 1;
        |       ^
       8|

  assertion 'false' failed
  ----------------------------------------------------- show-trace -----------------------------------------------------
  trace: while evaluating the attribute 'x' of the derivation 'hello-2.10'
  at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix

     191|         // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) {
     192|           name = "${attrs.pname}-${attrs.version}";
        |           ^
     193|         } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) {

Example after:

  error: assertion 'false' failed

         at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix

              6|
              7|   x = assert false; 1;
               |       ^
              8|

         … while evaluating the attribute 'x' of the derivation 'hello-2.10'

         at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix

            191|         // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) {
            192|           name = "${attrs.pname}-${attrs.version}";
               |           ^
            193|         } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) {
This commit is contained in:
Eelco Dolstra 2021-01-21 00:27:36 +01:00
parent 259100332f
commit 8d4268d190
31 changed files with 249 additions and 422 deletions
Download patch file Download diff file Expand all files Collapse all files

169
src/libutil/error.cc
View file

@ -204,168 +204,109 @@ void printAtPos(const string & prefix, const ErrPos & pos, std::ostream & out)
}
}
static std::string indent(std::string_view indentFirst, std::string_view indentRest, std::string_view s)
{
std::string res;
bool first = true;
while (!s.empty()) {
auto end = s.find('\n');
if (!first) res += "\n";
res += first ? indentFirst : indentRest;
res += s.substr(0, end);
first = false;
if (end == s.npos) break;
s = s.substr(end + 1);
}
return res;
}
std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool showTrace)
{
auto errwidth = std::max<size_t>(getWindowSize().second, 20);
string prefix = "";
string levelString;
std::string prefix;
switch (einfo.level) {
case Verbosity::lvlError: {
levelString = ANSI_RED;
levelString += "error:";
levelString += ANSI_NORMAL;
prefix = ANSI_RED "error";
break;
}
case Verbosity::lvlNotice: {
prefix = ANSI_RED "note";
break;
}
case Verbosity::lvlWarn: {
levelString = ANSI_YELLOW;
levelString += "warning:";
levelString += ANSI_NORMAL;
prefix = ANSI_YELLOW "warning";
break;
}
case Verbosity::lvlInfo: {
levelString = ANSI_GREEN;
levelString += "info:";
levelString += ANSI_NORMAL;
prefix = ANSI_GREEN "info";
break;
}
case Verbosity::lvlTalkative: {
levelString = ANSI_GREEN;
levelString += "talk:";
levelString += ANSI_NORMAL;
prefix = ANSI_GREEN "talk";
break;
}
case Verbosity::lvlChatty: {
levelString = ANSI_GREEN;
levelString += "chat:";
levelString += ANSI_NORMAL;
prefix = ANSI_GREEN "chat";
break;
}
case Verbosity::lvlVomit: {
levelString = ANSI_GREEN;
levelString += "vomit:";
levelString += ANSI_NORMAL;
prefix = ANSI_GREEN "vomit";
break;
}
case Verbosity::lvlDebug: {
levelString = ANSI_YELLOW;
levelString += "debug:";
levelString += ANSI_NORMAL;
break;
}
default: {
levelString = fmt("invalid error level: %1%", einfo.level);
prefix = ANSI_YELLOW "debug";
break;
}
default:
assert(false);
}
auto ndl = prefix.length()
+ filterANSIEscapes(levelString, true).length()
+ 7
+ einfo.name.length()
+ einfo.programName.value_or("").length();
auto dashwidth = std::max<int>(errwidth - ndl, 3);
std::string dashes(dashwidth, '-');
// divider.
if (einfo.name != "")
out << fmt("%1%%2%" ANSI_BLUE " --- %3% %4% %5%" ANSI_NORMAL,
prefix,
levelString,
einfo.name,
dashes,
einfo.programName.value_or(""));
// FIXME: show the program name as part of the trace?
if (einfo.programName && einfo.programName != ErrorInfo::programName)
prefix += fmt(" [%s]:" ANSI_NORMAL " ", einfo.programName.value_or(""));
else
out << fmt("%1%%2%" ANSI_BLUE " -----%3% %4%" ANSI_NORMAL,
prefix,
levelString,
dashes,
einfo.programName.value_or(""));
prefix += ":" ANSI_NORMAL " ";
bool nl = false; // intersperse newline between sections.
if (einfo.errPos.has_value() && (*einfo.errPos)) {
out << prefix << std::endl;
printAtPos(prefix, *einfo.errPos, out);
nl = true;
}
std::ostringstream oss;
oss << einfo.msg << "\n";
// description
if (einfo.description != "") {
if (nl)
out << std::endl << prefix;
out << std::endl << prefix << einfo.description;
nl = true;
}
if (einfo.errPos.has_value() && *einfo.errPos) {
oss << "\n";
printAtPos("", *einfo.errPos, oss);
if (einfo.errPos.has_value() && (*einfo.errPos)) {
auto loc = getCodeLines(*einfo.errPos);
// lines of code.
if (loc.has_value()) {
if (nl)
out << std::endl << prefix;
printCodeLines(out, prefix, *einfo.errPos, *loc);
nl = true;
oss << "\n";
printCodeLines(oss, "", *einfo.errPos, *loc);
oss << "\n";
}
}
// hint
if (einfo.hint.has_value()) {
if (nl)
out << std::endl << prefix;
out << std::endl << prefix << *einfo.hint;
nl = true;
}
// traces
if (showTrace && !einfo.traces.empty())
{
const string tracetitle(" show-trace ");
int fill = errwidth - tracetitle.length();
int lw = 0;
int rw = 0;
const int min_dashes = 3;
if (fill > min_dashes * 2) {
if (fill % 2 != 0) {
lw = fill / 2;
rw = lw + 1;
}
else
{
lw = rw = fill / 2;
}
}
else
lw = rw = min_dashes;
if (nl)
out << std::endl << prefix;
out << ANSI_BLUE << std::string(lw, '-') << tracetitle << std::string(rw, '-') << ANSI_NORMAL;
for (auto iter = einfo.traces.rbegin(); iter != einfo.traces.rend(); ++iter)
{
out << std::endl << prefix;
out << ANSI_BLUE << "trace: " << ANSI_NORMAL << iter->hint.str();
if (showTrace && !einfo.traces.empty()) {
for (auto iter = einfo.traces.rbegin(); iter != einfo.traces.rend(); ++iter) {
oss << "\n" << "… " << iter->hint.str() << "\n";
if (iter->pos.has_value() && (*iter->pos)) {
auto pos = iter->pos.value();
out << std::endl << prefix;
printAtPos(prefix, pos, out);
oss << "\n";
printAtPos("", pos, oss);
auto loc = getCodeLines(pos);
if (loc.has_value())
{
out << std::endl << prefix;
printCodeLines(out, prefix, pos, *loc);
out << std::endl << prefix;
if (loc.has_value()) {
oss << "\n";
printCodeLines(oss, "", pos, *loc);
oss << "\n";
}
}
}
}
out << indent(prefix, std::string(filterANSIEscapes(prefix, true).size(), ' '), chomp(oss.str()));
return out;
}
}

19
src/libutil/error.hh
View file

@ -107,9 +107,8 @@ struct Trace {
struct ErrorInfo {
Verbosity level;
string name;
string description; // FIXME: remove? it seems to be barely used
std::optional<hintformat> hint;
string name; // FIXME: rename
hintformat msg;
std::optional<ErrPos> errPos;
std::list<Trace> traces;
@ -133,23 +132,17 @@ public:
template<typename... Args>
BaseError(unsigned int status, const Args & ... args)
: err {.level = lvlError,
.hint = hintfmt(args...)
}
: err { .level = lvlError, .msg = hintfmt(args...) }
, status(status)
{ }
template<typename... Args>
BaseError(const std::string & fs, const Args & ... args)
: err {.level = lvlError,
.hint = hintfmt(fs, args...)
}
: err { .level = lvlError, .msg = hintfmt(fs, args...) }
{ }
BaseError(hintformat hint)
: err {.level = lvlError,
.hint = hint
}
: err { .level = lvlError, .msg = hint }
{ }
BaseError(ErrorInfo && e)
@ -206,7 +199,7 @@ public:
{
errNo = errno;
auto hf = hintfmt(args...);
err.hint = hintfmt("%1%: %2%", normaltxt(hf.str()), strerror(errNo));
err.msg = hintfmt("%1%: %2%", normaltxt(hf.str()), strerror(errNo));
}
virtual const char* sname() const override { return "SysError"; }

7
src/libutil/logging.cc
View file

@ -184,7 +184,7 @@ struct JSONLogger : Logger {
json["action"] = "msg";
json["level"] = ei.level;
json["msg"] = oss.str();
json["raw_msg"] = ei.hint->str();
json["raw_msg"] = ei.msg.str();
if (ei.errPos.has_value() && (*ei.errPos)) {
json["line"] = ei.errPos->line;
@ -305,10 +305,7 @@ bool handleJSONLogMessage(const std::string & msg,
}
} catch (std::exception & e) {
logError({
.name = "JSON log message",
.hint = hintfmt("bad log message from builder: %s", e.what())
});
printError("bad JSON log message from builder: %s", e.what());
}
return true;

22
src/libutil/serialise.cc
View file

@ -52,10 +52,7 @@ size_t threshold = 256 * 1024 * 1024;
static void warnLargeDump()
{
logWarning({
.name = "Large path",
.description = "dumping very large path (> 256 MiB); this may run out of memory"
});
warn("dumping very large path (> 256 MiB); this may run out of memory");
}
@ -306,8 +303,7 @@ Sink & operator << (Sink & sink, const Error & ex)
<< "Error"
<< info.level
<< info.name
<< info.description
<< (info.hint ? info.hint->str() : "")
<< info.msg.str()
<< 0 // FIXME: info.errPos
<< info.traces.size();
for (auto & trace : info.traces) {
@ -374,12 +370,14 @@ Error readError(Source & source)
{
auto type = readString(source);
assert(type == "Error");
ErrorInfo info;
info.level = (Verbosity) readInt(source);
info.name = readString(source);
info.description = readString(source);
auto hint = readString(source);
if (hint != "") info.hint = hintformat(std::move(format("%s") % hint));
auto level = (Verbosity) readInt(source);
auto name = readString(source);
auto msg = readString(source);
ErrorInfo info {
.level = level,
.name = name,
.msg = hintformat(std::move(format("%s") % msg)),
};
auto havePos = readNum<size_t>(source);
assert(havePos == 0);
auto nrTraces = readNum<size_t>(source);

35
src/libutil/tests/logging.cc
View file

@ -1,3 +1,5 @@
#if 0
#include "logging.hh"
#include "nixexpr.hh"
#include "util.hh"
@ -41,8 +43,7 @@ namespace nix {
makeJSONLogger(*logger)->logEI({
.name = "error name",
.description = "error without any code lines.",
.hint = hintfmt("this hint has %1% templated %2%!!",
.msg = hintfmt("this hint has %1% templated %2%!!",
"yellow",
"values"),
.errPos = Pos(foFile, problem_file, 02, 13)
@ -62,7 +63,7 @@ namespace nix {
throw TestError(e.info());
} catch (Error &e) {
ErrorInfo ei = e.info();
ei.hint = hintfmt("%s; subsequent error message.", normaltxt(e.info().hint ? e.info().hint->str() : ""));
ei.msg = hintfmt("%s; subsequent error message.", normaltxt(e.info().msg.str()));
testing::internal::CaptureStderr();
logger->logEI(ei);
@ -95,7 +96,6 @@ namespace nix {
logger->logEI({ .level = lvlInfo,
.name = "Info name",
.description = "Info description",
});
auto str = testing::internal::GetCapturedStderr();
@ -109,7 +109,6 @@ namespace nix {
logger->logEI({ .level = lvlTalkative,
.name = "Talkative name",
.description = "Talkative description",
});
auto str = testing::internal::GetCapturedStderr();
@ -123,7 +122,6 @@ namespace nix {
logger->logEI({ .level = lvlChatty,
.name = "Chatty name",
.description = "Talkative description",
});
auto str = testing::internal::GetCapturedStderr();
@ -137,7 +135,6 @@ namespace nix {
logger->logEI({ .level = lvlDebug,
.name = "Debug name",
.description = "Debug description",
});
auto str = testing::internal::GetCapturedStderr();
@ -151,7 +148,6 @@ namespace nix {
logger->logEI({ .level = lvlVomit,
.name = "Vomit name",
.description = "Vomit description",
});
auto str = testing::internal::GetCapturedStderr();
@ -167,7 +163,6 @@ namespace nix {
logError({
.name = "name",
.description = "error description",
});
auto str = testing::internal::GetCapturedStderr();
@ -182,8 +177,7 @@ namespace nix {
logError({
.name = "error name",
.description = "error with code lines",
.hint = hintfmt("this hint has %1% templated %2%!!",
.msg = hintfmt("this hint has %1% templated %2%!!",
"yellow",
"values"),
.errPos = Pos(foString, problem_file, 02, 13),
@ -200,8 +194,7 @@ namespace nix {
logError({
.name = "error name",
.description = "error without any code lines.",
.hint = hintfmt("this hint has %1% templated %2%!!",
.msg = hintfmt("this hint has %1% templated %2%!!",
"yellow",
"values"),
.errPos = Pos(foFile, problem_file, 02, 13)
@ -216,7 +209,7 @@ namespace nix {
logError({
.name = "error name",
.hint = hintfmt("hint %1%", "only"),
.msg = hintfmt("hint %1%", "only"),
});
auto str = testing::internal::GetCapturedStderr();
@ -233,8 +226,7 @@ namespace nix {
logWarning({
.name = "name",
.description = "warning description",
.hint = hintfmt("there was a %1%", "warning"),
.msg = hintfmt("there was a %1%", "warning"),
});
auto str = testing::internal::GetCapturedStderr();
@ -250,8 +242,7 @@ namespace nix {
logWarning({
.name = "warning name",
.description = "warning description",
.hint = hintfmt("this hint has %1% templated %2%!!",
.msg = hintfmt("this hint has %1% templated %2%!!",
"yellow",
"values"),
.errPos = Pos(foStdin, problem_file, 2, 13),
@ -274,8 +265,7 @@ namespace nix {
auto e = AssertionError(ErrorInfo {
.name = "wat",
.description = "show-traces",
.hint = hintfmt("it has been %1% days since our last error", "zero"),
.msg = hintfmt("it has been %1% days since our last error", "zero"),
.errPos = Pos(foString, problem_file, 2, 13),
});
@ -301,8 +291,7 @@ namespace nix {
auto e = AssertionError(ErrorInfo {
.name = "wat",
.description = "hide traces",
.hint = hintfmt("it has been %1% days since our last error", "zero"),
.msg = hintfmt("it has been %1% days since our last error", "zero"),
.errPos = Pos(foString, problem_file, 2, 13),
});
@ -377,3 +366,5 @@ namespace nix {
}
}
#endif