[clang] [clang] Only use CheckVectorOperands for fixed-length vector operands (PR #170485)

[Benjamin Maxwell via cfe-commits]

https://github.com/MacDue updated https://github.com/llvm/llvm-project/pull/170485

>From 3e55858c79df00e3e2890279fc9673cd33931f29 Mon Sep 17 00:00:00 2001
From: Benjamin Maxwell <benjamin.maxwell at arm.com>
Date: Wed, 3 Dec 2025 14:28:16 +0000
Subject: [PATCH 1/2] [clang] Only use CheckVectorOperands for fixed-length
 vector operands

Fixes #170279
---
 clang/lib/Sema/SemaExprCXX.cpp                        |  4 +++-
 clang/test/Sema/AArch64/sve-vector-conditional-op.cpp | 10 ++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 69719ebd1fc8c..b5adc52a8450e 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -5724,12 +5724,14 @@ QualType Sema::CheckVectorConditionalTypes(ExprResult &Cond, ExprResult &LHS,
       ResultType = CheckSizelessVectorOperands(LHS, RHS, QuestionLoc,
                                                /*IsCompAssign*/ false,
                                                ArithConvKind::Conditional);
-    else
+    else if (LHSType->isVectorType() || LHSType->isVectorType())
       ResultType = CheckVectorOperands(
           LHS, RHS, QuestionLoc, /*isCompAssign*/ false, /*AllowBothBool*/ true,
           /*AllowBoolConversions*/ false,
           /*AllowBoolOperation*/ true,
           /*ReportInvalid*/ true);
+    else
+      return InvalidOperands(QuestionLoc, LHS, RHS);
     if (ResultType.isNull())
       return {};
   } else {
diff --git a/clang/test/Sema/AArch64/sve-vector-conditional-op.cpp b/clang/test/Sema/AArch64/sve-vector-conditional-op.cpp
index 0ca55e6268658..cda995ece744c 100644
--- a/clang/test/Sema/AArch64/sve-vector-conditional-op.cpp
+++ b/clang/test/Sema/AArch64/sve-vector-conditional-op.cpp
@@ -22,6 +22,16 @@ auto error_sve_vector_result_matched_element_count(__SVBool_t svbool, __SVUint32
   return svbool ? a : b;
 }
 
+auto error_fixed_cond_mixed_scalar_and_vector_operands(fixed_vector cond, unsigned char a, __SVUint8_t b) {
+  // expected-error at +1 {{invalid operands to binary expression ('unsigned char' and '__SVUint8_t')}}
+  return cond ? a : b;
+}
+
+auto error_scalable_cond_mixed_scalar_and_vector_operands(__SVBool_t svbool, unsigned char a, fixed_vector b) {
+  // expected-error at +1 {{cannot convert between vector and non-scalar values ('unsigned char' and 'fixed_vector' (vector of 1 'int' value))}}
+  return svbool ? a : b;
+}
+
 // The following cases should be supported:
 
 __SVBool_t cond_svbool(__SVBool_t a, __SVBool_t b) {

>From 5a25ee29730105e8593e4df5095de1764a3d0d91 Mon Sep 17 00:00:00 2001
From: Benjamin Maxwell <benjamin.maxwell at arm.com>
Date: Wed, 3 Dec 2025 16:29:42 +0000
Subject: [PATCH 2/2] Fix condition check for vector types in SemaExprCXX

---
 clang/lib/Sema/SemaExprCXX.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index b5adc52a8450e..ae59903ddc00e 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -5724,7 +5724,7 @@ QualType Sema::CheckVectorConditionalTypes(ExprResult &Cond, ExprResult &LHS,
       ResultType = CheckSizelessVectorOperands(LHS, RHS, QuestionLoc,
                                                /*IsCompAssign*/ false,
                                                ArithConvKind::Conditional);
-    else if (LHSType->isVectorType() || LHSType->isVectorType())
+    else if (LHSType->isVectorType() || RHSType->isVectorType())
       ResultType = CheckVectorOperands(
           LHS, RHS, QuestionLoc, /*isCompAssign*/ false, /*AllowBothBool*/ true,
           /*AllowBoolConversions*/ false,