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nix/src/libexpr/eval-inline.hh
Eelco Dolstra 8d4268d190 Improve error formatting
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)))) {
2021-01-21 11:02:09 +01:00

100 lines
2.1 KiB
C++

#pragma once
#include "eval.hh"
#define LocalNoInline(f) static f __attribute__((noinline)); f
#define LocalNoInlineNoReturn(f) static f __attribute__((noinline, noreturn)); f
namespace nix {
LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s))
{
throw EvalError({
.msg = hintfmt(s),
.errPos = pos
});
}
LocalNoInlineNoReturn(void throwTypeError(const char * s, const Value & v))
{
throw TypeError(s, showType(v));
}
LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const Value & v))
{
throw TypeError({
.msg = hintfmt(s, showType(v)),
.errPos = pos
});
}
void EvalState::forceValue(Value & v, const Pos & pos)
{
if (v.isThunk()) {
Env * env = v.thunk.env;
Expr * expr = v.thunk.expr;
try {
v.mkBlackhole();
//checkInterrupt();
expr->eval(*this, *env, v);
} catch (...) {
v.mkThunk(env, expr);
throw;
}
}
else if (v.isApp())
callFunction(*v.app.left, *v.app.right, v, noPos);
else if (v.isBlackhole())
throwEvalError(pos, "infinite recursion encountered");
}
inline void EvalState::forceAttrs(Value & v)
{
forceValue(v);
if (v.type() != nAttrs)
throwTypeError("value is %1% while a set was expected", v);
}
inline void EvalState::forceAttrs(Value & v, const Pos & pos)
{
forceValue(v, pos);
if (v.type() != nAttrs)
throwTypeError(pos, "value is %1% while a set was expected", v);
}
inline void EvalState::forceList(Value & v)
{
forceValue(v);
if (!v.isList())
throwTypeError("value is %1% while a list was expected", v);
}
inline void EvalState::forceList(Value & v, const Pos & pos)
{
forceValue(v, pos);
if (!v.isList())
throwTypeError(pos, "value is %1% while a list was expected", v);
}
/* Note: Various places expect the allocated memory to be zeroed. */
inline void * allocBytes(size_t n)
{
void * p;
#if HAVE_BOEHMGC
p = GC_MALLOC(n);
#else
p = calloc(n, 1);
#endif
if (!p) throw std::bad_alloc();
return p;
}
}