rts: More const correct-ness fixes

In addition to more const-correctness fixes this patch fixes an
infelicity of the previous const-correctness patch (995cf0f356) which
left `UNTAG_CLOSURE` taking a `const StgClosure` pointer parameter
but returning a non-const pointer. Here we restore the original type
signature of `UNTAG_CLOSURE` and add a new function
`UNTAG_CONST_CLOSURE` which takes and returns a const `StgClosure`
pointer and uses that wherever possible.

Test Plan: Validate on Linux, OS X and Windows

Reviewers: Phyx, hsyl20, bgamari, austin, simonmar, trofi

Reviewed By: simonmar, trofi

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2231

1 files changed, 5 insertions, 5 deletions

diff --git a/rts/Hash.c b/rts/Hash.c
index b0939c49bc..1b193e3247 100644
--- a/rts/Hash.c
+++ b/rts/Hash.c
@@ -29,7 +29,7 @@
 /* Linked list of (key, data) pairs for separate chaining */
 typedef struct hashlist {
     StgWord key;
-    void *data;
+    const void *data;
     struct hashlist *next;  /* Next cell in bucket chain (same hash value) */
 } HashList;
 
@@ -200,7 +200,7 @@ lookupHashTable(const HashTable *table, StgWord key)
 
     for (hl = table->dir[segment][index]; hl != NULL; hl = hl->next)
         if (table->compare(hl->key, key))
-            return hl->data;
+            return (void *) hl->data;
 
     /* It's not there */
     return NULL;
@@ -274,7 +274,7 @@ freeHashList (HashTable *table, HashList *hl)
 }
 
 void
-insertHashTable(HashTable *table, StgWord key, void *data)
+insertHashTable(HashTable *table, StgWord key, const void *data)
 {
     int bucket;
     int segment;
@@ -323,7 +323,7 @@ removeHashTable(HashTable *table, StgWord key, void *data)
                 prev->next = hl->next;
             freeHashList(table,hl);
             table->kcount--;
-            return hl->data;
+            return (void *) hl->data;
         }
         prev = hl;
     }
@@ -357,7 +357,7 @@ freeHashTable(HashTable *table, void (*freeDataFun)(void *) )
             for (hl = table->dir[segment][index]; hl != NULL; hl = next) {
                 next = hl->next;
                 if (freeDataFun != NULL)
-                    (*freeDataFun)(hl->data);
+                    (*freeDataFun)((void *) hl->data);
             }
             index--;
         }