Merge "Print top-level errors normally in nix repl" into main

This commit is contained in:
Rebecca Turner 2024-04-10 15:40:03 +00:00 committed by Gerrit Code Review
commit 99845e0e01
6 changed files with 120 additions and 62 deletions

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@ -1,6 +1,7 @@
--- ---
synopsis: Concise error printing in `nix repl` synopsis: Concise error printing in `nix repl`
prs: 9928 prs: 9928
cls: 811
--- ---
Previously, if an element of a list or attribute set threw an error while Previously, if an element of a list or attribute set threw an error while

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@ -167,7 +167,8 @@ struct NixRepl
.force = true, .force = true,
.derivationPaths = true, .derivationPaths = true,
.maxDepth = maxDepth, .maxDepth = maxDepth,
.prettyIndent = 2 .prettyIndent = 2,
.errors = ErrorPrintBehavior::ThrowTopLevel,
}); });
} }
}; };

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@ -8,6 +8,29 @@
namespace nix { namespace nix {
/**
* How errors should be handled when printing values.
*/
enum class ErrorPrintBehavior {
/**
* Print the first line of the error in brackets: `«error: oh no!»`
*/
Print,
/**
* Throw the error to the code that attempted to print the value, instead
* of suppressing it it.
*/
Throw,
/**
* Only throw the error if encountered at the top level of the expression.
*
* This will cause expressions like `builtins.throw "uh oh!"` to throw
* errors, but will print attribute sets and other nested structures
* containing values that error (like `nixpkgs`) normally.
*/
ThrowTopLevel,
};
/** /**
* Options for printing Nix values. * Options for printing Nix values.
*/ */
@ -68,6 +91,11 @@ struct PrintOptions
*/ */
size_t prettyIndent = 0; size_t prettyIndent = 0;
/**
* How to handle errors encountered while printing values.
*/
ErrorPrintBehavior errors = ErrorPrintBehavior::Print;
/** /**
* True if pretty-printing is enabled. * True if pretty-printing is enabled.
*/ */
@ -86,7 +114,7 @@ static PrintOptions errorPrintOptions = PrintOptions {
.maxDepth = 10, .maxDepth = 10,
.maxAttrs = 10, .maxAttrs = 10,
.maxListItems = 10, .maxListItems = 10,
.maxStringLength = 1024 .maxStringLength = 1024,
}; };
} }

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@ -229,7 +229,6 @@ private:
void printDerivation(Value & v) void printDerivation(Value & v)
{ {
try {
Bindings::iterator i = v.attrs->find(state.sDrvPath); Bindings::iterator i = v.attrs->find(state.sDrvPath);
NixStringContext context; NixStringContext context;
std::string storePath; std::string storePath;
@ -245,9 +244,6 @@ private:
output << "»"; output << "»";
if (options.ansiColors) if (options.ansiColors)
output << ANSI_NORMAL; output << ANSI_NORMAL;
} catch (Error & e) {
printError_(e);
}
} }
bool shouldPrettyPrintAttrs(AttrVec & v) bool shouldPrettyPrintAttrs(AttrVec & v)
@ -472,13 +468,9 @@ private:
output.flush(); output.flush();
checkInterrupt(); checkInterrupt();
if (options.force) {
try { try {
if (options.force) {
state.forceValue(v, v.determinePos(noPos)); state.forceValue(v, v.determinePos(noPos));
} catch (Error & e) {
printError_(e);
return;
}
} }
switch (v.type()) { switch (v.type()) {
@ -531,6 +523,14 @@ private:
printUnknown(); printUnknown();
break; break;
} }
} catch (Error & e) {
if (options.errors == ErrorPrintBehavior::Throw
|| (options.errors == ErrorPrintBehavior::ThrowTopLevel
&& depth == 0)) {
throw;
}
printError_(e);
}
} }
public: public:

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@ -0,0 +1,27 @@
Errors at the top of an expression are printed normally:
nix-repl> builtins.throw "Evil puppy detected!!!"
error:
… while calling the 'throw' builtin
at «string»:1:1:
1| builtins.throw "Evil puppy detected!!!"
| ^
error: Evil puppy detected!!!
Errors in attribute values are printed inline, to make it easier to explore
values like nixpkgs where some parts of the value fail to evaluate:
nix-repl> { puppy = builtins.throw "This puppy is EVIL!!!"; puppy2 = "This puppy is GOOD :)"; }
{
puppy = «error: This puppy is EVIL!!!»;
puppy2 = "This puppy is GOOD :)";
}
Same for list values:
nix-repl> [ (builtins.throw "This puppy is EVIL!!!") ("This puppy is GOOD :)") ]
[
«error: This puppy is EVIL!!!»
"This puppy is GOOD :)"
]

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@ -186,5 +186,6 @@ REPL_TEST(repl_overlays_destructure_without_formals_ok);
REPL_TEST(repl_overlays_error); REPL_TEST(repl_overlays_error);
REPL_TEST(repl_printing); REPL_TEST(repl_printing);
REPL_TEST(stack_vars); REPL_TEST(stack_vars);
REPL_TEST(errors);
}; // namespace nix }; // namespace nix