4c7165be86
Turns errors like this:
let
throwMsg = a: throw (a + " invalid bar");
in throwMsg "bullshit"
error:
… from call site
at «string»:3:4:
2| throwMsg = a: throw (a + " invalid bar");
3| in throwMsg "bullshit"
| ^
… while calling 'throwMsg'
at «string»:2:14:
1| let
2| throwMsg = a: throw (a + " invalid bar");
| ^
3| in throwMsg "bullshit"
… while calling the 'throw' builtin
at «string»:2:17:
1| let
2| throwMsg = a: throw (a + " invalid bar");
| ^
3| in throwMsg "bullshit"
error: bullshit invalid bar
into errors like this:
let
throwMsg = a: throw (a + " invalid bar");
in throwMsg "bullshit"
error:
… from call site
at «string»:3:4:
2| throwMsg = a: throw (a + " invalid bar");
3| in throwMsg "bullshit"
| ^
… while calling 'throwMsg'
at «string»:2:14:
1| let
2| throwMsg = a: throw (a + " invalid bar");
| ^
3| in throwMsg "bullshit"
… caused by explicit throw
at «string»:2:17:
1| let
2| throwMsg = a: throw (a + " invalid bar");
| ^
3| in throwMsg "bullshit"
error: bullshit invalid bar
Change-Id: I593688928ece20f97999d1bf03b2b46d9ac338cb
70 lines
2.2 KiB
Markdown
70 lines
2.2 KiB
Markdown
---
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synopsis: "Distinguish between explicit throws and errors that happened while evaluating a throw"
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cls: 1511
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credits: Qyriad
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category: Improvements
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---
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Previously, errors caused by an expression like `throw "invalid argument"` were treated like an error that happened simply while some builtin function was being called:
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```
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let
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throwMsg = p: throw "${p} isn't the right package";
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in throwMsg "linuz"
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error:
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… while calling the 'throw' builtin
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at «string»:2:17:
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1| let
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2| throwMsg = p: throw "${p} isn't the right package";
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| ^
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3| in throwMsg "linuz"
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error: linuz isn't the right package
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```
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But the error didn't just happen "while" calling the `throw` builtin — it's a throw error!
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Now it looks like this:
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```
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let
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throwMsg = p: throw "${p} isn't the right package";
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in throwMsg "linuz"
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error:
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… caused by explicit throw
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at «string»:2:17:
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1| let
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2| throwMsg = p: throw "${p} isn't the right package";
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| ^
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3| in throwMsg "linuz"
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error: linuz isn't the right package
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```
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This also means that incorrect usage of `throw` or errors evaluating its arguments are easily distinguishable from explicit throws:
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```
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let
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throwMsg = p: throw "${p} isn't the right package";
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in throwMsg { attrs = "error when coerced in string interpolation"; }
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error:
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… while calling the 'throw' builtin
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at «string»:2:17:
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1| let
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2| throwMsg = p: throw "${p} isn't the right package";
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| ^
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3| in throwMsg { attrs = "error when coerced in string interpolation"; }
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… while evaluating a path segment
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at «string»:2:24:
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1| let
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2| throwMsg = p: throw "${p} isn't the right package";
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| ^
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3| in throwMsg { attrs = "error when coerced in string interpolation"; }
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error: cannot coerce a set to a string: { attrs = "error when coerced in string interpolation"; }
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```
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Here, instead of an actual thrown error, a type error happens first (trying to coerce an attribute set to a string), but that type error happened *while* calling `throw`.
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