dynamic_alloc: Replace implicit type conversion with incorrect semant…

…ics by proper return value (microsoft#99)

The dynamic_alloc example fails to compile on Visual Studio 2015 due to an C4800 / C2220 compiler error (LONG status is used as return value). Apart from the performance warning, which is treated as error because of the /WX flag, the semantics of this operation seem to be wrong. At the end of the function, we find return status == NO_ERROR. That means that in line 70 a successful execution results in a return value of true and an unsuccessful execution results in false. However, if the function is left in line 52, the return code is true (because the test status != NO_ERROR was positive).

Fix this, and force /we4800 to be enabled to catch issues in the future. 

Co-authored-by: Brian Gianforcaro <[email protected]>

samples/common.mak

@@ -23,7 +23,7 @@ CLIB=/MT
 !ENDIF
 
 AFLAGS=/nologo /Zi /c /Fl
-CFLAGS=/nologo /Zi $(CLIB) /Gm- /W4 /WX /Od
+CFLAGS=/nologo /Zi $(CLIB) /Gm- /W4 /WX /we4800 /Od
 
 !IF $(DETOURS_SOURCE_BROWSING)==1
 CFLAGS=$(CFLAGS) /FR

samples/dynamic_alloc/main.cpp

@@ -49,7 +49,7 @@ bool DetourTransaction(std::function<bool()> callback) {
   LONG status = DetourTransactionBegin();
   if (status != NO_ERROR) {
     Log("DetourTransactionBegin failed with %08x\n", status);
-    return status;
+    return status == NO_ERROR;
   }
 
   if (callback()) {

src/Makefile

@@ -16,7 +16,7 @@ DETOURS_SOURCE_BROWSING = 0
 
 #######################/#######################################################
 ##
-CFLAGS=/nologo /W4 /WX /Zi /MT /Gy /Gm- /Zl /Od
+CFLAGS=/nologo /W4 /WX /we4800 /Zi /MT /Gy /Gm- /Zl /Od
 
 !IF $(DETOURS_SOURCE_BROWSING)==1
 CFLAGS=$(CFLAGS) /FR