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* When something goes wrong in the evaluation of a Nix expression,

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print a nice backtrace of the stack, rather than vomiting a gigantic
  (and useless) aterm on the screen.  Example:

    error: while evaluating file `.../pkgs/system/test.nix':
    while evaluating attribute `subversion' at `.../pkgs/system/all-packages-generic.nix', line 533:
    while evaluating function at `.../pkgs/applications/version-management/subversion/default.nix', line 1:
    assertion failed at `.../pkgs/applications/version-management/subversion/default.nix', line 13

  Since the Nix expression language is lazy, the trace may be
  misleading.  The purpose is to provide a hint as to the location of
  the problem.
This commit is contained in:
Eelco Dolstra 2004-04-05 22:27:41 +00:00
parent a520b1cbc3
commit 59b94ee18a
8 changed files with 201 additions and 90 deletions
Download patch file Download diff file Expand all files Collapse all files

27
src/libexpr/parser.cc
View file

@ -12,8 +12,8 @@
struct ParseData
{
Expr result;
string basePath;
string location;
Path basePath;
Path path;
string error;
};
@ -39,8 +39,8 @@ ATerm absParsedPath(ParseData * data, ATerm t)
void parseError(ParseData * data, char * error, int line, int column)
{
data->error = (format("%1%, at line %2%, column %3%, of %4%")
% error % line % column % data->location).str();
data->error = (format("%1%, at `%2%':%3%:%4%")
% error % data->path % line % column).str();
}
ATerm fixAttrs(int recursive, ATermList as)
@ -51,13 +51,15 @@ ATerm fixAttrs(int recursive, ATermList as)
for (ATermIterator i(as); i; ++i) {
ATermList names;
Expr src;
if (atMatch(m, *i) >> "Inherit" >> src >> names) {
ATerm pos;
if (atMatch(m, *i) >> "Inherit" >> src >> names >> pos) {
bool fromScope = atMatch(m, src) >> "Scope";
for (ATermIterator j(names); j; ++j) {
Expr rhs = fromScope
? ATmake("Var(<term>)", *j)
: ATmake("Select(<term>, <term>)", src, *j);
*is = ATinsert(*is, ATmake("Bind(<term>, <term>)", *j, rhs));
*is = ATinsert(*is, ATmake("Bind(<term>, <term>, <term>)",
*j, rhs, pos));
}
} else bs = ATinsert(bs, *i);
}
@ -67,18 +69,23 @@ ATerm fixAttrs(int recursive, ATermList as)
return ATmake("Attrs(<term>)", bs);
}
const char * getPath(ParseData * data)
{
return data->path.c_str();
}
int yyparse(yyscan_t scanner, ParseData * data);
}
static Expr parse(EvalState & state,
const char * text, const string & location,
const char * text, const Path & path,
const Path & basePath)
{
yyscan_t scanner;
ParseData data;
data.basePath = basePath;
data.location = location;
data.path = path;
yylex_init(&scanner);
yy_scan_string(text, scanner);
@ -90,7 +97,7 @@ static Expr parse(EvalState & state,
try {
checkVarDefs(state.primOpsAll, data.result);
} catch (Error & e) {
throw Error(format("%1%, in %2%") % e.msg() % location);
throw Error(format("%1%, in `%2%'") % e.msg() % path);
}
return data.result;
@ -133,7 +140,7 @@ Expr parseExprFromFile(EvalState & state, Path path)
readFull(fd, (unsigned char *) text, st.st_size);
text[st.st_size] = 0;
return parse(state, text, "`" + path + "'", dirOf(path));
return parse(state, text, path, dirOf(path));
}