ptext SLIT("at ") <+> ppr loc1,
ptext SLIT("and") <+> ppr loc2]
\end{code}
+
+
+\begin{code}
+checkEarlyExit mod_name
+ = traceRn (text "Considering whether compilation is required...") `thenRn_`
+
+ -- Read the old interface file, if any, for the module being compiled
+ findAndReadIface doc_str mod_name False {- Not hi-boot -} `thenRn` \ maybe_iface ->
+
+ -- CHECK WHETHER WE HAVE IT ALREADY
+ case maybe_iface of
+ Left err -> -- Old interface file not found, so we'd better bail out
+ traceRn (vcat [ptext SLIT("No old interface file for") <+> ppr mod_name,
+ err]) `thenRn_`
+ returnRn (outOfDate, Nothing)
+
+ Right iface
+ | panic "checkEarlyExit: ???: not opt_SourceUnchanged"
+ -> -- Source code changed
+ traceRn (nest 4 (text "source file changed or recompilation check turned off")) `thenRn_`
+ returnRn (False, Just iface)
+
+ | otherwise
+ -> -- Source code unchanged and no errors yet... carry on
+ checkModUsage (pi_usages iface) `thenRn` \ up_to_date ->
+ returnRn (up_to_date, Just iface)
+ where
+ -- Only look in current directory, with suffix .hi
+ doc_str = sep [ptext SLIT("need usage info from"), ppr mod_name]
+\end{code}
+
+%********************************************************
+%* *
+\subsection{Checking usage information}
+%* *
+%********************************************************
+
+\begin{code}
+upToDate = True
+outOfDate = False
+
+checkModUsage :: [ImportVersion OccName] -> RnMG Bool
+-- Given the usage information extracted from the old
+-- M.hi file for the module being compiled, figure out
+-- whether M needs to be recompiled.
+
+checkModUsage [] = returnRn upToDate -- Yes! Everything is up to date!
+
+checkModUsage ((mod_name, _, _, NothingAtAll) : rest)
+ -- If CurrentModule.hi contains
+ -- import Foo :: ;
+ -- then that simply records that Foo lies below CurrentModule in the
+ -- hierarchy, but CurrentModule doesn't depend in any way on Foo.
+ -- In this case we don't even want to open Foo's interface.
+ = traceRn (ptext SLIT("Nothing used from:") <+> ppr mod_name) `thenRn_`
+ checkModUsage rest -- This one's ok, so check the rest
+
+checkModUsage ((mod_name, _, _, whats_imported) : rest)
+ = tryLoadInterface doc_str mod_name ImportBySystem `thenRn` \ (ifaces, maybe_err) ->
+ case maybe_err of {
+ Just err -> out_of_date (sep [ptext SLIT("Can't find version number for module"),
+ ppr mod_name]) ;
+ -- Couldn't find or parse a module mentioned in the
+ -- old interface file. Don't complain -- it might just be that
+ -- the current module doesn't need that import and it's been deleted
+
+ Nothing ->
+ let
+ (_, new_mod_vers, new_fix_vers, new_rule_vers, _, _)
+ = case lookupFM (iImpModInfo ifaces) mod_name of
+ Just (_, _, Just stuff) -> stuff
+
+ old_mod_vers = case whats_imported of
+ Everything v -> v
+ Specifically v _ _ _ -> v
+ -- NothingAtAll case dealt with by previous eqn for checkModUsage
+ in
+ -- If the module version hasn't changed, just move on
+ if new_mod_vers == old_mod_vers then
+ traceRn (sep [ptext SLIT("Module version unchanged:"), ppr mod_name])
+ `thenRn_` checkModUsage rest
+ else
+ traceRn (sep [ptext SLIT("Module version has changed:"), ppr mod_name])
+ `thenRn_`
+ -- Module version changed, so check entities inside
+
+ -- If the usage info wants to say "I imported everything from this module"
+ -- it does so by making whats_imported equal to Everything
+ -- In that case, we must recompile
+ case whats_imported of { -- NothingAtAll dealt with earlier
+
+ Everything _
+ -> out_of_date (ptext SLIT("...and I needed the whole module")) ;
+
+ Specifically _ old_fix_vers old_rule_vers old_local_vers ->
+
+ if old_fix_vers /= new_fix_vers then
+ out_of_date (ptext SLIT("Fixities changed"))
+ else if old_rule_vers /= new_rule_vers then
+ out_of_date (ptext SLIT("Rules changed"))
+ else
+ -- Non-empty usage list, so check item by item
+ checkEntityUsage mod_name (iDecls ifaces) old_local_vers `thenRn` \ up_to_date ->
+ if up_to_date then
+ traceRn (ptext SLIT("...but the bits I use haven't.")) `thenRn_`
+ checkModUsage rest -- This one's ok, so check the rest
+ else
+ returnRn outOfDate -- This one failed, so just bail out now
+ }}
+ where
+ doc_str = sep [ptext SLIT("need version info for"), ppr mod_name]
+
+
+checkEntityUsage mod decls []
+ = returnRn upToDate -- Yes! All up to date!
+
+checkEntityUsage mod decls ((occ_name,old_vers) : rest)
+ = newGlobalName mod occ_name `thenRn` \ name ->
+ case lookupNameEnv decls name of
+
+ Nothing -> -- We used it before, but it ain't there now
+ out_of_date (sep [ptext SLIT("No longer exported:"), ppr name])
+
+ Just (new_vers,_,_,_) -- It's there, but is it up to date?
+ | new_vers == old_vers
+ -- Up to date, so check the rest
+ -> checkEntityUsage mod decls rest
+
+ | otherwise
+ -- Out of date, so bale out
+ -> out_of_date (sep [ptext SLIT("Out of date:"), ppr name])
+
+out_of_date msg = traceRn msg `thenRn_` returnRn outOfDate
+\end{code}
+
+
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