Fix #15953 by consistently using dumpIfSet_dyn to print debug output

Summary:
In some modules we directly dump the debugging output to STDOUT
via 'putLogMsg', 'printInfoForUser' etc. However, if `-ddump-to-file`
is enabled, that output should be written to a file. Easily fixed.

Certain tests (T3017, Roles3, T12763 etc.) expect part of the
output generated by `-ddump-types` to be in 'PprUser' style. However,
generally we want all other debugging output to use 'PprDump'
style. `traceTcRn` and `traceTcRnForUser` help us accomplish this.

This patch also documents some missing flags in the users guide.

Reviewers: RyanGlScott, bgamari, hvr

Reviewed By: RyanGlScott

Subscribers: rwbarton, carter

GHC Trac Issues: #15953

Differential Revision: https://phabricator.haskell.org/D5382

1 files changed, 3 insertions, 4 deletions

diff --git a/compiler/main/Packages.hs b/compiler/main/Packages.hs
index 2ee2136581..70c9c26c11 100644
--- a/compiler/main/Packages.hs
+++ b/compiler/main/Packages.hs
@@ -82,7 +82,7 @@ import Maybes
 
 import System.Environment ( getEnv )
 import FastString
-import ErrUtils         ( debugTraceMsg, MsgDoc, printInfoForUser )
+import ErrUtils         ( debugTraceMsg, MsgDoc, dumpIfSet_dyn )
 import Exception
 
 import System.Directory
@@ -1583,9 +1583,8 @@ mkPackageState dflags dbs preload0 = do
       mod_map2 = mkUnusableModuleToPkgConfAll unusable
       mod_map = Map.union mod_map1 mod_map2
 
-  when (dopt Opt_D_dump_mod_map dflags) $
-      printInfoForUser (dflags { pprCols = 200 })
-                       alwaysQualify (pprModuleMap mod_map)
+  dumpIfSet_dyn (dflags { pprCols = 200 }) Opt_D_dump_mod_map "Mod Map"
+    (pprModuleMap mod_map)
 
   -- Force pstate to avoid leaking the dflags0 passed to mkPackageState
   let !pstate = PackageState{