RtsFlags: Fix const warning

Reviewers: austin

Reviewed By: austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1509

1 files changed, 8 insertions, 1 deletions

diff --git a/rts/RtsFlags.c b/rts/RtsFlags.c
index e3051287e6..94572792de 100644
--- a/rts/RtsFlags.c
+++ b/rts/RtsFlags.c
@@ -1531,9 +1531,15 @@ static void read_debug_flags(const char* arg)
 
 #ifdef PROFILING
 // Parse a "-h" flag, returning whether the parse resulted in an error.
-static rtsBool read_heap_profiling_flag(const char *arg)
+static rtsBool read_heap_profiling_flag(const char *arg_in)
 {
     // Already parsed "-h"
+
+    // For historical reasons the parser here mutates the arguments.
+    // However, for sanity we want to guarantee const-correctness and parsing
+    // really ought to be an immutable operation. To avoid rewriting the parser
+    // we just operate on a temporary copy of the argument.
+    char *arg = strdup(arg_in);
     rtsBool error = rtsFalse;
     switch (arg[2]) {
     case '\0':
@@ -1638,6 +1644,7 @@ static rtsBool read_heap_profiling_flag(const char *arg)
         error = rtsTrue;
     }
 
+    free(arg);
     return error;
 }
 #endif