[OCaml] Use LLVMCreateMessage with constant strings when calling llvm_raise

[jketema]

Summary

The llvm_string_of_message function, called by llvm_raise, calls LLVMDisposeMessage, which expects the message to be dynamically allocated; it fails freeing the message otherwise. So always dynamically allocate with LLVMCreateMessage.

[whitequark]

LGTM

[whitequark]

By the way, it would be wonderful if you found a moment to add support for LLVMContextSetDiagnosticHandler—it's in my backlog for a while, but I'm unlikely to get to it soon... right now the error messages from the OCaml bindings are quite useless.

[jketema]

Yeah something needs to be done with LLVMContextSetDiagnosticHandler anyway, as two regression tests currently fail because no handler is installed. I might do an easy fix for that first (just to get the tests back in working order) and then revisit how to properly expose the handlers.

bindings/ocaml/analysis/analysis_ocaml.c

 |* This file glues LLVM's OCaml interface to its C interface. These functions *|
 |* are by and large transparent wrappers to the corresponding C functions.    *|
 |*                                                                            *|
 |* Note that these functions intentionally take liberties with the CAMLparamX *|
 |* macros, since most of the parameters are not GC heap objects.              *|
 |*                                                                            *|
 \*===----------------------------------------------------------------------===*/
 
-#include "llvm-c/Core.h"
 #include "llvm-c/Analysis.h"
+#include "llvm-c/Core.h"
 #include "caml/alloc.h"
 #include "caml/mlvalues.h"
 #include "caml/memory.h"
 
 /* Llvm.llmodule -> string option */
 CAMLprim value llvm_verify_module(LLVMModuleRef M) {
   CAMLparam0();
   CAMLlocal2(String, Option);

bindings/ocaml/bitreader/bitreader_ocaml.c

 /*===-- bitwriter_ocaml.c - LLVM OCaml Glue ---------------------*- C++ -*-===*\
 |*                                                                            *|
 |*                     The LLVM Compiler Infrastructure                       *|
 |*                                                                            *|
 |* This file is distributed under the University of Illinois Open Source      *|
 |* License. See LICENSE.TXT for details.                                      *|
 |*                                                                            *|
 |*===----------------------------------------------------------------------===*|
 |*                                                                            *|
 |* This file glues LLVM's OCaml interface to its C interface. These functions *|
 |* are by and large transparent wrappers to the corresponding C functions.    *|
 |*                                                                            *|
 \*===----------------------------------------------------------------------===*/
 
 #include "llvm-c/BitReader.h"
+#include "llvm-c/Core.h"
 #include "caml/alloc.h"
 #include "caml/fail.h"
 #include "caml/memory.h"
 #include "caml/callback.h"
 
 void llvm_raise(value Prototype, char *Message);
 
 /* Llvm.llcontext -> Llvm.llmemorybuffer -> Llvm.llmodule */
 CAMLprim LLVMModuleRef llvm_get_module(LLVMContextRef C, LLVMMemoryBufferRef MemBuf) {
   LLVMModuleRef M;
 
   if (LLVMGetBitcodeModuleInContext2(C, MemBuf, &M))
-    llvm_raise(*caml_named_value("Llvm_bitreader.Error"), "");
+    llvm_raise(*caml_named_value("Llvm_bitreader.Error"), LLVMCreateMessage(""));
 
   return M;
 }
 
 /* Llvm.llcontext -> Llvm.llmemorybuffer -> Llvm.llmodule */
 CAMLprim LLVMModuleRef llvm_parse_bitcode(LLVMContextRef C, LLVMMemoryBufferRef MemBuf) {
   LLVMModuleRef M;
 
   if (LLVMParseBitcodeInContext2(C, MemBuf, &M))
-    llvm_raise(*caml_named_value("Llvm_bitreader.Error"), "");
+    llvm_raise(*caml_named_value("Llvm_bitreader.Error"), LLVMCreateMessage(""));
 
   return M;
 }

bindings/ocaml/linker/linker_ocaml.c

 |* This file glues LLVM's OCaml interface to its C interface. These functions *|
 |* are by and large transparent wrappers to the corresponding C functions.    *|
 |*                                                                            *|
 |* Note that these functions intentionally take liberties with the CAMLparamX *|
 |* macros, since most of the parameters are not GC heap objects.              *|
 |*                                                                            *|
 \*===----------------------------------------------------------------------===*/
 
+#include "llvm-c/Core.h"
 #include "llvm-c/Linker.h"
 #include "caml/alloc.h"
 #include "caml/memory.h"
 #include "caml/fail.h"
 #include "caml/callback.h"
 
 void llvm_raise(value Prototype, char *Message);
 
 /* llmodule -> llmodule -> unit */
 CAMLprim value llvm_link_modules(LLVMModuleRef Dst, LLVMModuleRef Src) {
   if (LLVMLinkModules2(Dst, Src))
-    llvm_raise(*caml_named_value("Llvm_linker.Error"), "Linking failed");
+    llvm_raise(*caml_named_value("Llvm_linker.Error"), LLVMCreateMessage("Linking failed"));
 
   return Val_unit;
 }

bindings/ocaml/llvm/llvm_ocaml.c

 |* macros, since most of the parameters are not GC heap objects.              *|
 |*                                                                            *|
 \*===----------------------------------------------------------------------===*/
 
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 #include "llvm-c/Core.h"
+#include "llvm-c/Support.h"
 #include "caml/alloc.h"
 #include "caml/custom.h"
 #include "caml/memory.h"
 #include "caml/fail.h"
 #include "caml/callback.h"
 
 value llvm_string_of_message(char* Message) {
   value String = caml_copy_string(Message);