* Add a Nix expression search path feature. Paths between angle
brackets, e.g.
import <nixpkgs/pkgs/lib>
are resolved by looking them up relative to the elements listed in
the search path. This allows us to get rid of hacks like
import "${builtins.getEnv "NIXPKGS_ALL"}/pkgs/lib"
The search path can be specified through the ‘-I’ command-line flag
and through the colon-separated ‘NIX_PATH’ environment variable,
e.g.,
$ nix-build -I /etc/nixos ...
If a file is not found in the search path, an error message is
lazily thrown.
This commit is contained in:
Eelco Dolstra
parent
54945a2950
commit
1ecc97b6bd
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@ -36,6 +36,10 @@
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<para>TODO: “or” keyword.</para>
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</listitem>
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<listitem>
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<para>TODO: Nix expression search path (<literal>import <foo/bar.nix></literal>).</para>
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</listitem>
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</itemizedlist>
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</section>
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@ -76,10 +76,10 @@ EOF
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$outLink = $ARGV[$n];
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}
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elsif ($arg eq "--attr" or $arg eq "-A") {
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elsif ($arg eq "--attr" or $arg eq "-A" or $arg eq "-I") {
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$n++;
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die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
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push @instArgs, ("--attr", $ARGV[$n]);
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push @instArgs, ($arg, $ARGV[$n]);
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}
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elsif ($arg eq "--arg" || $arg eq "--argstr") {
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@ -33,5 +33,15 @@ bool parseOptionArg(const string & arg, Strings::iterator & i,
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return true;
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}
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bool parseSearchPathArg(const string & arg, Strings::iterator & i,
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const Strings::iterator & argsEnd, EvalState & state)
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{
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if (arg != "-I") return false;
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if (i == argsEnd) throw UsageError(format("`%1%' requires an argument") % arg);;
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state.addToSearchPath(*i++);
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return true;
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}
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}
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@ -11,6 +11,9 @@ bool parseOptionArg(const string & arg, Strings::iterator & i,
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const Strings::iterator & argsEnd, EvalState & state,
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Bindings & autoArgs);
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bool parseSearchPathArg(const string & arg, Strings::iterator & i,
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const Strings::iterator & argsEnd, EvalState & state);
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}
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@ -181,6 +181,12 @@ EvalState::EvalState()
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gcInitialised = true;
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}
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#endif
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/* Initialise the Nix expression search path. */
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searchPathInsertionPoint = searchPath.end();
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Strings paths = tokenizeString(getEnv("NIX_PATH", ""), ":");
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foreach (Strings::iterator, i, paths) addToSearchPath(*i);
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searchPathInsertionPoint = searchPath.begin();
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}
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@ -213,11 +213,16 @@ private:
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std::map<Path, Expr *> parseTrees;
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Paths searchPath;
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Paths::iterator searchPathInsertionPoint;
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public:
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EvalState();
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~EvalState();
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void addToSearchPath(const string & s);
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/* Parse a Nix expression from the specified file. If `path'
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refers to a directory, then "/default.nix" is appended. */
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Expr * parseExprFromFile(Path path);
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@ -229,6 +234,9 @@ public:
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form. */
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void evalFile(const Path & path, Value & v);
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/* Look up a file in the search path. */
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Path findFile(const string & path);
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/* Evaluate an expression to normal form, storing the result in
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value `v'. */
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void eval(Expr * e, Value & v);
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@ -81,6 +81,7 @@ static Expr * unescapeStr(SymbolTable & symbols, const char * s)
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ID [a-zA-Z\_][a-zA-Z0-9\_\']*
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INT [0-9]+
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PATH [a-zA-Z0-9\.\_\-\+]*(\/[a-zA-Z0-9\.\_\-\+]+)+
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SPATH \<[a-zA-Z0-9\.\_\-\+]+(\/[a-zA-Z0-9\.\_\-\+]+)*\>
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URI [a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+
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@ -153,6 +154,7 @@ or { return OR_KW; }
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<IND_STRING>. return yytext[0]; /* just in case: shouldn't be reached */
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{PATH} { yylval->path = strdup(yytext); return PATH; }
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{SPATH} { yylval->path = strdup(yytext); return SPATH; }
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{URI} { yylval->uri = strdup(yytext); return URI; }
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[ \t\r\n]+ /* eat up whitespace */
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@ -17,19 +17,22 @@
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#include "util.hh"
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#include "nixexpr.hh"
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#include "eval.hh"
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namespace nix {
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struct ParseData
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{
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EvalState & state;
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SymbolTable & symbols;
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Expr * result;
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Path basePath;
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Path path;
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string error;
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Symbol sLetBody;
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ParseData(SymbolTable & symbols)
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: symbols(symbols)
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ParseData(EvalState & state)
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: state(state)
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, symbols(state.symbols)
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, sLetBody(symbols.create("<let-body>"))
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{ };
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};
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@ -253,7 +256,7 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
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%token <id> ID ATTRPATH
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%token <e> STR IND_STR
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%token <n> INT
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%token <path> PATH
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%token <path> PATH SPATH
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%token <uri> URI
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%token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL OR_KW
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%token DOLLAR_CURLY /* == ${ */
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@ -350,6 +353,20 @@ expr_simple
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$$ = stripIndentation(data->symbols, *$2);
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}
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| PATH { $$ = new ExprPath(absPath($1, data->basePath)); }
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| SPATH {
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string path($1 + 1, strlen($1) - 2);
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Path path2 = data->state.findFile(path);
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/* The file wasn't found in the search path. However, we can't
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throw an error here, because the expression might never be
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evaluated. So return an expression that lazily calls
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‘abort’. */
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$$ = path2 == ""
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? (Expr * ) new ExprApp(
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new ExprVar(data->symbols.create("throw")),
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new ExprString(data->symbols.create(
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(format("file `%1%' was not found in the Nix search path (add it using $NIX_PATH or -I)") % path).str())))
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: (Expr * ) new ExprPath(path2);
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}
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| URI { $$ = new ExprString(data->symbols.create($1)); }
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| '(' expr ')' { $$ = $2; }
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/* Let expressions `let {..., body = ...}' are just desugared
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@ -454,7 +471,7 @@ Expr * EvalState::parse(const char * text,
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const Path & path, const Path & basePath)
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{
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yyscan_t scanner;
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ParseData data(symbols);
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ParseData data(*this);
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data.basePath = basePath;
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data.path = path;
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@ -510,5 +527,25 @@ Expr * EvalState::parseExprFromString(const string & s, const Path & basePath)
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return parse(s.c_str(), "(string)", basePath);
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}
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void EvalState::addToSearchPath(const string & s)
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{
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Path path = absPath(s);
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if (pathExists(path)) {
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debug(format("adding path `%1%' to the search path") % path);
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searchPath.insert(searchPathInsertionPoint, path);
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}
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}
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Path EvalState::findFile(const string & path)
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{
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foreach (Paths::iterator, i, searchPath) {
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Path res = *i + "/" + path;
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if (pathExists(res)) return canonPath(res);
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}
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return "";
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}
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}
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@ -1253,6 +1253,8 @@ void run(Strings args)
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else if (parseOptionArg(arg, i, args.end(),
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globals.state, globals.instSource.autoArgs))
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;
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else if (parseSearchPathArg(arg, i, args.end(), globals.state))
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;
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else if (arg == "--force-name") // undocumented flag for nix-install-package
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globals.forceName = needArg(i, args, arg);
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else if (arg == "--uninstall" || arg == "-e")
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@ -107,6 +107,8 @@ void run(Strings args)
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}
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else if (parseOptionArg(arg, i, args.end(), state, autoArgs))
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;
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else if (parseSearchPathArg(arg, i, args.end(), state))
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;
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else if (arg == "--add-root") {
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if (i == args.end())
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throw UsageError("`--add-root' requires an argument");
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@ -40,7 +40,7 @@ for i in lang/eval-okay-*.nix; do
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if test -e lang/$i.flags; then
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flags=$(cat lang/$i.flags)
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fi
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if ! $nixinstantiate $flags --eval-only --strict lang/$i.nix > lang/$i.out; then
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if ! NIX_PATH=lang/dir3:lang/dir4 $nixinstantiate $flags --eval-only --strict lang/$i.nix > lang/$i.out; then
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echo "FAIL: $i should evaluate"
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fail=1
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elif ! diff lang/$i.out lang/$i.exp; then
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@ -0,0 +1 @@
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"a"
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@ -0,0 +1 @@
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"X"
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@ -0,0 +1 @@
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"b"
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@ -0,0 +1 @@
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"X"
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@ -0,0 +1 @@
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"X"
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@ -0,0 +1 @@
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"c"
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@ -0,0 +1 @@
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"X"
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@ -0,0 +1 @@
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"X"
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@ -0,0 +1 @@
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"abc"
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@ -0,0 +1 @@
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-I lang/dir1 -I lang/dir2
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@ -0,0 +1,3 @@
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import <a.nix> + import <b.nix> + import <c.nix>
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@ -0,0 +1 @@
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(import <a.nix>)
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@ -0,0 +1 @@
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"abc"
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