[clang] f63bd03 - [CIR] Handle CK_UserDefinedConversion and related casts in emitCastLValue (#193611)

[via cfe-commits]

Author: adams381
Date: 2026-04-23T13:45:47-05:00
New Revision: f63bd03c1db0e11fd22a7a7eeea7a7a961accc2e

URL: https://github.com/llvm/llvm-project/commit/f63bd03c1db0e11fd22a7a7eeea7a7a961accc2e
DIFF: https://github.com/llvm/llvm-project/commit/f63bd03c1db0e11fd22a7a7eeea7a7a961accc2e.diff

LOG: [CIR] Handle CK_UserDefinedConversion and related casts in emitCastLValue (#193611)

`emitCastLValue` was hitting an NYI error for
`CK_UserDefinedConversion`, `CK_ConstructorConversion`,
`CK_CPointerToObjCPointerCast`, `CK_BlockPointerToObjCPointerCast`, and
`CK_LValueToRValue`. Classic codegen handles all of these as a
pass-through to the sub-expression (`CGExpr.cpp:6197`), and CIR should
do the same.

Made with [Cursor](https://cursor.com)

Added: 
    clang/test/CIR/CodeGen/cast-lvalue-conv.cpp

Modified: 
    clang/lib/CIR/CodeGen/CIRGenExpr.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/CIR/CodeGen/CIRGenExpr.cpp b/clang/lib/CIR/CodeGen/CIRGenExpr.cpp
index aeef7c910e62e..92a520e1237d3 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExpr.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExpr.cpp
@@ -1508,15 +1508,17 @@ LValue CIRGenFunction::emitCastLValue(const CastExpr *e) {
   case CK_ToUnion:
     return emitAggExprToLValue(e);
 
-  case CK_NonAtomicToAtomic:
-  case CK_AtomicToNonAtomic:
-  case CK_ObjCObjectLValueCast:
-  case CK_VectorSplat:
   case CK_ConstructorConversion:
   case CK_UserDefinedConversion:
   case CK_CPointerToObjCPointerCast:
   case CK_BlockPointerToObjCPointerCast:
-  case CK_LValueToRValue: {
+  case CK_LValueToRValue:
+    return emitLValue(e->getSubExpr());
+
+  case CK_NonAtomicToAtomic:
+  case CK_AtomicToNonAtomic:
+  case CK_ObjCObjectLValueCast:
+  case CK_VectorSplat: {
     cgm.errorNYI(e->getSourceRange(),
                  std::string("emitCastLValue for unhandled cast kind: ") +
                      e->getCastKindName());

diff  --git a/clang/test/CIR/CodeGen/cast-lvalue-conv.cpp b/clang/test/CIR/CodeGen/cast-lvalue-conv.cpp
new file mode 100644
index 0000000000000..164b97966e6d8
--- /dev/null
+++ b/clang/test/CIR/CodeGen/cast-lvalue-conv.cpp
@@ -0,0 +1,57 @@
+// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --check-prefix=LLVM --input-file=%t-cir.ll %s
+// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o %t.ll
+// RUN: FileCheck --check-prefix=OGCG --input-file=%t.ll %s
+
+// Test CK_ConstructorConversion and CK_UserDefinedConversion
+// in emitCastLValue (pass-through to sub-expression).
+
+struct Source {
+  int val;
+  operator int() const { return val; }
+};
+
+struct Dest {
+  int val;
+  Dest(const Source &s) : val(s.val) {}
+};
+
+// CK_ConstructorConversion: implicit conversion via constructor
+// when binding a reference.
+void takeDestRef(const Dest &d);
+
+void testConstructorConversion() {
+  Source s{42};
+  takeDestRef(s);
+}
+
+// CIR-LABEL: cir.func {{.*}} @_Z25testConstructorConversionv
+// CIR:   cir.call @_ZN4DestC1ERK6Source
+// CIR:   cir.call @_Z11takeDestRefRK4Dest
+
+// LLVM-LABEL: define {{.*}} @_Z25testConstructorConversionv
+// LLVM:   call void @_ZN4DestC1ERK6Source
+// LLVM:   call void @_Z11takeDestRefRK4Dest
+
+// OGCG-LABEL: define {{.*}} @_Z25testConstructorConversionv
+// OGCG:   call void @_ZN4DestC1ERK6Source
+// OGCG:   call void @_Z11takeDestRefRK4Dest
+
+// CK_UserDefinedConversion: implicit conversion via operator.
+void takeInt(int x);
+
+int testUserDefinedConversion() {
+  Source s{7};
+  return static_cast<int>(s);
+}
+
+// CIR-LABEL: cir.func {{.*}} @_Z25testUserDefinedConversionv
+// CIR:   cir.call @_ZNK6SourcecviEv
+
+// LLVM-LABEL: define {{.*}} @_Z25testUserDefinedConversionv
+// LLVM:   call noundef i32 @_ZNK6SourcecviEv
+
+// OGCG-LABEL: define {{.*}} @_Z25testUserDefinedConversionv
+// OGCG:   call noundef i32 @_ZNK6SourcecviEv