diff options
| author | Simon Peyton Jones <simonpj@microsoft.com> | 2012-10-04 17:55:38 +0100 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2012-10-04 17:55:38 +0100 |
| commit | b9fccbc8bc377cde8e75bce8c78470e3c4fa4018 (patch) | |
| tree | dcc0de15f0e1d44a6cbabfd1d12468776a5b6a32 /compiler | |
| parent | 629d1f48b513be3cc662ea79376737dbcdb6b18f (diff) | |
| download | haskell-b9fccbc8bc377cde8e75bce8c78470e3c4fa4018.tar.gz | |
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.
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/typecheck/TcSimplify.lhs | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs index c0ff59d793..09a5b11c22 100644 --- a/compiler/typecheck/TcSimplify.lhs +++ b/compiler/typecheck/TcSimplify.lhs @@ -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) |