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Simon Peyton Jones pushed to branch wip/T25325 at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
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<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/904852da052e0f3b5df8b2c979fa07105f5f5227">904852da</a></strong>
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<span> by Simon Peyton Jones </span> <i> at 2024-10-07T16:34:12+01:00 </i>
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compiler/GHC/Tc/Types/Constraint.hs
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<a href="https://gitlab.haskell.org/ghc/ghc/-/commit/904852da052e0f3b5df8b2c979fa07105f5f5227#3b6d78a50c8462304f843b952a88e531718dbbd2"><strong style="font-weight: 600;">compiler/GHC/Tc/Types/Constraint.hs</strong></a>
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<td class="diff-line-num unfold js-unfold old_line" data-linenumber="1327" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">...</td>
<td class="diff-line-num unfold js-unfold new_line" data-linenumber="1327" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">...</td>
<td class="line_content match" style="color: rgba(5,5,6,.24); padding: inherit;" bgcolor="#fbfafd">@@ -1327,7 +1327,7 @@ insolubleWC (WC { wc_impl = implics, wc_simple = simples, wc_errors = errors })</td>
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<td class="old_line diff-line-num" data-linenumber="1327" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1327
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<td class="new_line diff-line-num" data-linenumber="1327" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1327
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1327" class="line" lang="haskell"><span class="n" style="color: #333;">insolubleWantedCt</span> <span class="o" style="font-weight: 600;">::</span> <span class="kt" style="color: #458; font-weight: 600;">Ct</span> <span class="o" style="font-weight: 600;">-></span> <span class="kt" style="color: #458; font-weight: 600;">Bool</span></span>
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<td class="old_line diff-line-num" data-linenumber="1328" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1328
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<td class="new_line diff-line-num" data-linenumber="1328" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1328
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1328" class="line" lang="haskell"><span class="c1" style="color: #998; font-style: italic;">-- Definitely insoluble, in particular /excluding/ type-hole constraints</span></span>
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<td class="old_line diff-line-num" data-linenumber="1329" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1329
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<td class="new_line diff-line-num" data-linenumber="1329" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1329
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1329" class="line" lang="haskell"><span class="c1" style="color: #998; font-style: italic;">-- Namely:</span></span>
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<td class="old_line diff-line-num old" data-linenumber="1330" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
1330
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<td class="new_line diff-line-num old" data-linenumber="1330" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC1330" class="line" lang="haskell"><span class="c1" style="color: #998; font-style: italic;">-- a) an insoluble constraint as per 'insoluble<span class="idiff left right deletion" style="background-color: #fac5cd;">i</span>rredCt', i.e. either</span></span>
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<td class="old_line diff-line-num new" data-linenumber="1331" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="new_line diff-line-num new" data-linenumber="1330" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
1330
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1330" class="line" lang="haskell"><span class="c1" style="color: #998; font-style: italic;">-- a) an insoluble constraint as per 'insoluble<span class="idiff left right addition" style="background-color: #c7f0d2;">I</span>rredCt', i.e. either</span></span>
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<td class="old_line diff-line-num" data-linenumber="1331" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1331
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<td class="new_line diff-line-num" data-linenumber="1331" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1331
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1331" class="line" lang="haskell"><span class="c1" style="color: #998; font-style: italic;">-- - an insoluble equality constraint (e.g. Int ~ Bool), or</span></span>
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1332
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<td class="new_line diff-line-num" data-linenumber="1332" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1332
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1332" class="line" lang="haskell"><span class="c1" style="color: #998; font-style: italic;">-- - a custom type error constraint, TypeError msg :: Constraint</span></span>
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1333
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<td class="new_line diff-line-num" data-linenumber="1333" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1333
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1333" class="line" lang="haskell"><span class="c1" style="color: #998; font-style: italic;">-- b) that does not arise from a Given or a Wanted/Wanted fundep interaction</span></span>
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<td class="diff-line-num unfold js-unfold old_line" data-linenumber="1341" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">...</td>
<td class="diff-line-num unfold js-unfold new_line" data-linenumber="1341" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">...</td>
<td class="line_content match" style="color: rgba(5,5,6,.24); padding: inherit;" bgcolor="#fbfafd">@@ -1341,7 +1341,7 @@ insolubleWantedCt ct</td>
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<td class="old_line diff-line-num" data-linenumber="1341" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1341
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<td class="new_line diff-line-num" data-linenumber="1341" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1341
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1341" class="line" lang="haskell"> <span class="p">,</span> <span class="n" style="color: #333;">insolubleIrredCt</span> <span class="n" style="color: #333;">ir_ct</span></span>
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<td class="old_line diff-line-num" data-linenumber="1342" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1342
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<td class="new_line diff-line-num" data-linenumber="1342" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1342
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1342" class="line" lang="haskell"> <span class="c1" style="color: #998; font-style: italic;">-- It's insoluble</span></span>
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<td class="old_line diff-line-num" data-linenumber="1343" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1343
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<td class="new_line diff-line-num" data-linenumber="1343" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1343
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1343" class="line" lang="haskell"> <span class="p">,</span> <span class="n" style="color: #333;">isEmptyRewriterSet</span> <span class="n" style="color: #333;">rewriters</span></span>
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<td class="old_line diff-line-num old" data-linenumber="1344" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
1344
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<td class="new_line diff-line-num old" data-linenumber="1344" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC1344" class="line" lang="haskell"> <span class="c1" style="color: #998; font-style: italic;">-- rewriters; see (IW2) in Note [Insoluble Wanteds]</span></span>
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<td class="new_line diff-line-num new" data-linenumber="1344" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
1344
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1344" class="line" lang="haskell"> <span class="c1" style="color: #998; font-style: italic;">-- <span class="idiff left right addition" style="background-color: #c7f0d2;">It has no </span>rewriters; see (IW2) in Note [Insoluble Wanteds]</span></span>
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1345
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<td class="new_line diff-line-num" data-linenumber="1345" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1345
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1345" class="line" lang="haskell"> <span class="p">,</span> <span class="n" style="color: #333;">not</span> <span class="p">(</span><span class="n" style="color: #333;">isGivenLoc</span> <span class="n" style="color: #333;">loc</span><span class="p">)</span></span>
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1346
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1346
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1347
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1347" class="line" lang="haskell"> <span class="p">,</span> <span class="n" style="color: #333;">not</span> <span class="p">(</span><span class="n" style="color: #333;">isWantedWantedFunDepOrigin</span> <span class="p">(</span><span class="n" style="color: #333;">ctLocOrigin</span> <span class="n" style="color: #333;">loc</span><span class="p">))</span></span>
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<td class="line_content match" style="color: rgba(5,5,6,.24); padding: inherit;" bgcolor="#fbfafd">@@ -1441,14 +1441,14 @@ can't be solved. But not quite all such constraints; see wrinkles.</td>
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1441
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1441
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1441" class="line" lang="haskell"></span>
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<td class="old_line diff-line-num" data-linenumber="1442" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1442
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<td class="new_line diff-line-num" data-linenumber="1442" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1442
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1442" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;">(IW1) insolubleWantedCt is tuned for application /after/ constraint</span></span>
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<td class="old_line diff-line-num" data-linenumber="1443" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1443
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<td class="new_line diff-line-num" data-linenumber="1443" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1443
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1443" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> solving i.e. assuming canonicalisation has been done. That's why</span></span>
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<td class="old_line diff-line-num old" data-linenumber="1444" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
1444
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<td class="new_line diff-line-num old" data-linenumber="1444" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC1444" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> it looks only for IrredCt; all insoluble constraints <span class="idiff left right deletion" style="background-color: #fac5cd;">o</span>are put into</span></span>
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<td class="old_line diff-line-num new" data-linenumber="1445" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="new_line diff-line-num new" data-linenumber="1444" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
1444
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1444" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> it looks only for IrredCt; all insoluble constraints are put into</span></span>
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1445
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1445" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> CIrredCan</span></span>
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1446
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1446
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1446" class="line" lang="haskell"></span>
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1447
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<td class="new_line diff-line-num" data-linenumber="1447" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1447
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1447" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;">(IW2) We only treat it as insoluble if it has an empty rewriter set. (See Note</span></span>
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<td class="old_line diff-line-num" data-linenumber="1448" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1448
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<td class="new_line diff-line-num" data-linenumber="1448" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1448
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1448" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> [Wanteds rewrite Wanteds].) Otherwise #25325 happens: a Wanted constraint A</span></span>
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<td class="old_line diff-line-num" data-linenumber="1449" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1449
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<td class="new_line diff-line-num" data-linenumber="1449" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1449
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1449" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> that is /not/ insoluble rewrites some other Wanted constraint B, so B has A</span></span>
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<td class="old_line diff-line-num" data-linenumber="1450" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1450
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<td class="new_line diff-line-num" data-linenumber="1450" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1450
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1450" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> in its rewriter set. Now B looks insoluble. The danger is that we'll</span></span>
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<td class="old_line diff-line-num old" data-linenumber="1451" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
1451
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<td class="new_line diff-line-num old" data-linenumber="1451" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC1451" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> suppress reporting B bec<span class="idiff left right deletion" style="background-color: #fac5cd;">u</span>ase of its empty rewriter set; and suppress</span></span>
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<td class="old_line diff-line-num new" data-linenumber="1452" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="new_line diff-line-num new" data-linenumber="1451" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
1451
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1451" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> suppress reporting B beca<span class="idiff left right addition" style="background-color: #c7f0d2;">u</span>se of its empty rewriter set; and suppress</span></span>
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1452
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<td class="new_line diff-line-num" data-linenumber="1452" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1452
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1452" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> reporting A because there is an insoluble B lying around. (This suppression</span></span>
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<td class="old_line diff-line-num" data-linenumber="1453" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1453
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<td class="new_line diff-line-num" data-linenumber="1453" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1453
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1453" class="line" lang="haskell"><span class="cm" style="color: #998; font-style: italic;"> happens in GHC.Tc.Errors.mkErrorItem.) Solution: don't treat B as insoluble.</span></span>
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1454
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1454" class="line" lang="haskell"></span>
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