Testsuite: don't warn about missing specialisations

They can only occur with `-O`, but we want tests to produce the same
output for all test ways.

This brings us closer to passing the complete testsuite.

Differential Revision: https://phabricator.haskell.org/D1203

compiler/specialise/Specialise.hs

@@ -738,6 +738,7 @@ warnMissingSpecs :: DynFlags -> [Id] -> Bool
 -- See Note [Warning about missed specialisations]
 warnMissingSpecs dflags callers
   | wopt Opt_WarnAllMissedSpecs dflags = True
+  | not (wopt Opt_WarnMissedSpecs dflags) = False
   | null callers                       = False
   | otherwise                          = all has_inline_prag callers
   where

testsuite/mk/test.mk

@@ -44,6 +44,10 @@ TEST_HC_OPTS = -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-
 #
 TEST_HC_OPTS += -fno-warn-tabs
 
+# Don't warn about missing specialisations. They can only occur with `-O`, but
+# we want tests to produce the same output for all test ways.
+TEST_HC_OPTS += -fno-warn-missed-specialisations
+
 RUNTEST_OPTS =
 
 ifeq "$(filter $(TargetOS_CPP), cygwin32 mingw32)" ""