Compiler: correctly copy anonymous struct types from other contexts. Fixes #4078 . Fixes #4082

Ary Borenszweig · Ary Borenszweig · commit e586dd23b487 · 2017-03-01T12:28:23.000-03:00
diff --git a/spec/compiler/codegen/c_abi/c_abi_x86_64_spec.cr b/spec/compiler/codegen/c_abi/c_abi_x86_64_spec.cr
@@ -85,6 +85,30 @@ require "../../../spec_helper"
       str.should contain("declare void @foo({ i64, i64 })")
     end
 
+    it "passes struct between 64 and 128 bits as { i64, i64 } (with multiple modules/contexts)" do
+      codegen(%(
+        require "prelude"
+
+        lib LibFoo
+          struct Struct
+            x : Int64
+            y : Int16
+          end
+
+          fun foo(s : Struct)
+        end
+
+        module Moo
+          def self.moo
+            s = LibFoo::Struct.new
+            LibFoo.foo(s)
+          end
+        end
+
+        Moo.moo
+        ))
+    end
+
     it "passes struct between 64 and 128 bits (for real)" do
       test_c(
         %(
diff --git a/src/compiler/crystal/codegen/llvm_typer.cr b/src/compiler/crystal/codegen/llvm_typer.cr
@@ -523,11 +523,17 @@ module Crystal
         LLVM::Type.function(params_types, ret_type, type.varargs?)
       when .struct?
         llvm_name = type.struct_name
-        @structs[llvm_name] ||= begin
-          @llvm_context.struct(llvm_name, type.packed_struct?) do |the_struct|
-            @structs[llvm_name] = the_struct
-            copy_types(type.struct_element_types)
+        if llvm_name
+          @structs[llvm_name] ||= begin
+            @llvm_context.struct(llvm_name, type.packed_struct?) do |the_struct|
+              @structs[llvm_name] = the_struct
+              copy_types(type.struct_element_types)
+            end
           end
+        else
+          # The case of an anonymous struct (only happens with C bindings and C ABI,
+          # where structs like `{ double, double }` are generated)
+          @llvm_context.struct(copy_types(type.struct_element_types), packed: type.packed_struct?)
         end
       else
         raise "don't know how to copy type: #{type} (#{type.kind})"
diff --git a/src/llvm/type.cr b/src/llvm/type.cr
@@ -63,10 +63,14 @@ struct LLVM::Type
     LibLLVM.is_packed_struct(self) != 0
   end
 
-  def struct_name
+  # Assuming this type is a struct, returns its name.
+  # The name can be `nil` if the struct is anynomous.
+  # Raises if this type is not a struct.
+  def struct_name : String?
     raise "not a Struct" unless kind == Kind::Struct
 
-    String.new(LibLLVM.get_struct_name(self))
+    name = LibLLVM.get_struct_name(self)
+    name ? String.new(name) : nil
   end
 
   def struct_element_types
