CodeView debug information for Windows does not like "non-class" methods.

Following [Rust's solution](rust-lang/rust#35991 (comment)), we make a dummy scope for primitive methods.

This change also reorders some imports in codegen.h and gendebug.cc, as gendebug.h now depends on having PONY_LLVM defined.

Author: chalcolith

src/libponyc/codegen/codegen.h

@@ -1,12 +1,6 @@
 #ifndef CODEGEN_H
 #define CODEGEN_H
 
-#include "gendebug.h"
-#include "../reach/reach.h"
-#include "../pass/pass.h"
-#include "../ast/ast.h"
-#include "../ast/printbuf.h"
-
 #include <platform.h>
 #include <llvm-c/Core.h>
 #include <llvm-c/Target.h>
@@ -15,10 +9,16 @@
 #include <llvm-c/Analysis.h>
 #include <stdio.h>
 
-PONY_EXTERN_C_BEGIN
-
 #define PONY_LLVM ((LLVM_VERSION_MAJOR * 100) + LLVM_VERSION_MINOR)
 
+#include "gendebug.h"
+#include "../reach/reach.h"
+#include "../pass/pass.h"
+#include "../ast/ast.h"
+#include "../ast/printbuf.h"
+
+PONY_EXTERN_C_BEGIN
+
 // Missing from C API.
 char* LLVMGetHostCPUName();
 char* LLVMGetHostCPUFeatures();

src/libponyc/codegen/gendebug.cc

@@ -1,5 +1,5 @@
-#include "gendebug.h"
 #include "codegen.h"
+#include "gendebug.h"
 
 #ifdef _MSC_VER
 #  pragma warning(push)
@@ -97,6 +97,18 @@ LLVMMetadataRef LLVMDIBuilderCreateFile(LLVMDIBuilderRef d, const char* file)
   return wrap(pd->createFile(filename, dir));
 }
 
+#if PONY_LLVM >= 309
+
+LLVMMetadataRef LLVMDIBuilderCreateNamespace(LLVMDIBuilderRef d, 
+  LLVMMetadataRef scope, const char* name, LLVMMetadataRef file, unsigned line)
+{
+  DIBuilder* pd = unwrap(d);
+  return wrap(pd->createNameSpace(unwrap<DIScope>(scope), name, 
+    unwrap<DIFile>(file), line));
+}
+
+#endif
+
 LLVMMetadataRef LLVMDIBuilderCreateLexicalBlock(LLVMDIBuilderRef d,
   LLVMMetadataRef scope, LLVMMetadataRef file, unsigned line, unsigned col)
 {

src/libponyc/codegen/gendebug.h

@@ -54,6 +54,12 @@ LLVMMetadataRef LLVMDIBuilderCreateCompileUnit(LLVMDIBuilderRef d,
 
 LLVMMetadataRef LLVMDIBuilderCreateFile(LLVMDIBuilderRef d, const char* file);
 
+#if PONY_LLVM >= 309
+LLVMMetadataRef LLVMDIBuilderCreateNamespace(LLVMDIBuilderRef d, 
+  LLVMMetadataRef scope, const char* name, LLVMMetadataRef file, 
+  unsigned line);
+#endif
+
 LLVMMetadataRef LLVMDIBuilderCreateLexicalBlock(LLVMDIBuilderRef d,
   LLVMMetadataRef scope, LLVMMetadataRef file, unsigned line, unsigned col);
 

src/libponyc/codegen/genfun.c

@@ -189,6 +189,15 @@ static void make_function_debug(compile_t* c, reach_type_t* t,
   else
     scope = c_t->di_type;
 
+#if PONY_LLVM >= 309 && defined(_MSC_VER)
+  // CodeView on Windows doesn't like "non-class" methods
+  if (c_t->primitive != NULL)
+  {
+    scope = LLVMDIBuilderCreateNamespace(c->di, c->di_unit, t->name, 
+      c_t->di_file, (unsigned)ast_line(t->ast));
+  }
+#endif
+
   c_m->di_method = LLVMDIBuilderCreateMethod(c->di, scope, ast_name(id),
     m->full_name, c_m->di_file, (unsigned)ast_line(m->r_fun), subroutine, func,
     c->opt->release);