Commit b9fccbc8 authored by Simon Peyton Jones's avatar Simon Peyton Jones

Do not do type-class defaulting if there are insoluble constraints

Type-class defaulting won't help with those insolubles,
and it does make arbitrary choices that obfuscate the
error messages from the insolubles.
parent 629d1f48
......@@ -79,7 +79,9 @@ simplifyTop wanteds
; simpl_top_loop wc_first_go }
simpl_top_loop wc
| isEmptyWC wc
| isEmptyWC wc || insolubleWC wc
-- Don't do type-class defaulting if there are insolubles
-- Doing so is not going to solve the insolubles
= return wc
| otherwise
= do { wc_residual <- nestTcS (solve_wanteds_and_drop wc)
......
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