[cxx-interop] Fix calling rvalue ref of a trivial type

Gabor Horvath · Gabor Horvath · commit 6b863f9575ab · 2025-04-06T18:58:12.000+01:00
The Swift compiler used to generate a direct call to functions taking
rvalue references to trivial types even though they expected an indirect
calling conventions. This PR changes the calling convention on the Swift
side to match C++.

rdar://148585343
diff --git a/lib/SIL/IR/SILFunctionType.cpp b/lib/SIL/IR/SILFunctionType.cpp
@@ -1543,6 +1543,9 @@ static bool isClangTypeMoreIndirectThanSubstType(TypeConverter &TC,
   if (importer::isCxxConstReferenceType(clangTy))
     return true;
 
+  if (clangTy->isRValueReferenceType())
+    return true;
+
   return false;
 }
 
diff --git a/test/Interop/Cxx/reference/reference.swift b/test/Interop/Cxx/reference/reference.swift
@@ -103,4 +103,9 @@ ReferenceTestSuite.test("const reference to template") {
   expectEqual(53, ref.pointee)
 }
 
+ReferenceTestSuite.test("rvalue reference of trivial type") {
+  setStaticIntRvalueRef(consuming: 2)
+  expectEqual(2, getStaticInt())
+}
+
 runAllTests()

Original file line number	Diff line number	Diff line change
`@@ -1543,6 +1543,9 @@ static bool isClangTypeMoreIndirectThanSubstType(TypeConverter &TC,`
`1543`	`1543`	`if (importer::isCxxConstReferenceType(clangTy))`
`1544`	`1544`	`return true;`
`1545`	`1545`
	`1546`	`+ if (clangTy->isRValueReferenceType())`
	`1547`	`+ return true;`
	`1548`	`+`
`1546`	`1549`	`return false;`
`1547`	`1550`	`}`
`1548`	`1551`
Original file line number	Diff line number	Diff line change
`@@ -103,4 +103,9 @@ ReferenceTestSuite.test("const reference to template") {`
`103`	`103`	`expectEqual(53, ref.pointee)`
`104`	`104`	`}`
`105`	`105`
	`106`	`+ReferenceTestSuite.test("rvalue reference of trivial type") {`
	`107`	`+ setStaticIntRvalueRef(consuming: 2)`
	`108`	`+ expectEqual(2, getStaticInt())`
	`109`	`+}`
	`110`	`+`
`106`	`111`	`runAllTests()`