manual c function interop

compiler/ir/ir.odin

@@ -7,6 +7,21 @@ import "core:mem"
 
 INVALID_ID :: -1
 
+Calling_Convention :: enum {
+	Brolang,
+	C,
+}
+
+Implementation :: enum {
+	Definition,
+	Declaration,
+}
+
+Linkage :: enum {
+	Internal,
+	External,
+}
+
 Opcode :: enum {
 	Param,
 	Const,
@@ -35,13 +50,15 @@ Instruction :: struct {
 }
 
 Function :: struct {
-	link_name:    string,
-	c_abi:        bool,
-	is_main:      bool,
-	param_types:  []types.Type,
-	result:       types.Type,
-	instructions: []Instruction,
-	problematic:  bool,
+	link_name:          string,
+	calling_convention: Calling_Convention,
+	implementation:     Implementation,
+	linkage:            Linkage,
+	is_main:            bool,
+	param_types:        []types.Type,
+	result:             types.Type,
+	instructions:       []Instruction,
+	problematic:        bool,
 }
 
 Global :: struct {