[clang] Ensure fixed point conversions work in C++ (#68344)

5 files changed, 56 insertions, 4 deletions

diff --git a/clang/include/clang/Sema/Overload.h b/clang/include/clang/Sema/Overload.h
index a97968d..333309a 100644
--- a/clang/include/clang/Sema/Overload.h
+++ b/clang/include/clang/Sema/Overload.h
@@ -192,6 +192,9 @@ class Sema;
     /// C-only conversion between pointers with incompatible types
     ICK_Incompatible_Pointer_Conversion,
 
+    /// Fixed point type conversions according to N1169.
+    ICK_Fixed_Point_Conversion,
+
     /// The number of conversion kinds
     ICK_Num_Conversion_Kinds,
   };
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index a6cd0bb..da8e2db 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -148,6 +148,9 @@ bool Sema::isSimpleTypeSpecifier(tok::TokenKind Kind) const {
   case tok::kw___ibm128:
   case tok::kw_wchar_t:
   case tok::kw_bool:
+  case tok::kw__Accum:
+  case tok::kw__Fract:
+  case tok::kw__Sat:
 #define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) case tok::kw___##Trait:
 #include "clang/Basic/TransformTypeTraits.def"
   case tok::kw___auto_type:
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 023411c..081b568 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -4506,6 +4506,36 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
                  .get();
     break;
 
+  case ICK_Fixed_Point_Conversion:
+    assert((FromType->isFixedPointType() || ToType->isFixedPointType()) &&
+           "Attempting implicit fixed point conversion without a fixed "
+           "point operand");
+    if (FromType->isFloatingType())
+      From = ImpCastExprToType(From, ToType, CK_FloatingToFixedPoint,
+                               VK_PRValue,
+                               /*BasePath=*/nullptr, CCK).get();
+    else if (ToType->isFloatingType())
+      From = ImpCastExprToType(From, ToType, CK_FixedPointToFloating,
+                               VK_PRValue,
+                               /*BasePath=*/nullptr, CCK).get();
+    else if (FromType->isIntegralType(Context))
+      From = ImpCastExprToType(From, ToType, CK_IntegralToFixedPoint,
+                               VK_PRValue,
+                               /*BasePath=*/nullptr, CCK).get();
+    else if (ToType->isIntegralType(Context))
+      From = ImpCastExprToType(From, ToType, CK_FixedPointToIntegral,
+                               VK_PRValue,
+                               /*BasePath=*/nullptr, CCK).get();
+    else if (ToType->isBooleanType())
+      From = ImpCastExprToType(From, ToType, CK_FixedPointToBoolean,
+                               VK_PRValue,
+                               /*BasePath=*/nullptr, CCK).get();
+    else
+      From = ImpCastExprToType(From, ToType, CK_FixedPointCast,
+                               VK_PRValue,
+                               /*BasePath=*/nullptr, CCK).get();
+    break;
+
   case ICK_Compatible_Conversion:
     From = ImpCastExprToType(From, ToType, CK_NoOp, From->getValueKind(),
                              /*BasePath=*/nullptr, CCK).get();
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 858654e..9800d7f 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -158,7 +158,8 @@ ImplicitConversionRank clang::GetConversionRank(ImplicitConversionKind Kind) {
                      // it was omitted by the patch that added
                      // ICK_Zero_Queue_Conversion
     ICR_C_Conversion,
-    ICR_C_Conversion_Extension
+    ICR_C_Conversion_Extension,
+    ICR_Conversion,
   };
   static_assert(std::size(Rank) == (int)ICK_Num_Conversion_Kinds);
   return Rank[(int)Kind];
@@ -197,7 +198,8 @@ static const char* GetImplicitConversionName(ImplicitConversionKind Kind) {
     "OpenCL Zero Event Conversion",
     "OpenCL Zero Queue Conversion",
     "C specific type conversion",
-    "Incompatible pointer conversion"
+    "Incompatible pointer conversion",
+    "Fixed point conversion",
   };
   static_assert(std::size(Name) == (int)ICK_Num_Conversion_Kinds);
   return Name[Kind];
@@ -2189,6 +2191,9 @@ static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
              From->isIntegerConstantExpr(S.getASTContext())) {
     SCS.Second = ICK_Compatible_Conversion;
     FromType = ToType;
+  } else if (ToType->isFixedPointType() || FromType->isFixedPointType()) {
+    SCS.Second = ICK_Fixed_Point_Conversion;
+    FromType = ToType;
   } else {
     // No second conversion required.
     SCS.Second = ICK_Identity;
@@ -5947,6 +5952,7 @@ static bool CheckConvertedConstantConversions(Sema &S,
   case ICK_Zero_Event_Conversion:
   case ICK_C_Only_Conversion:
   case ICK_Incompatible_Pointer_Conversion:
+  case ICK_Fixed_Point_Conversion:
     return false;
 
   case ICK_Lvalue_To_Rvalue:
diff --git a/clang/test/Frontend/fixed_point_conversions.c b/clang/test/Frontend/fixed_point_conversions.c
index ebd1d7e..efa3f1b 100644
--- a/clang/test/Frontend/fixed_point_conversions.c
+++ b/clang/test/Frontend/fixed_point_conversions.c
@@ -1,6 +1,12 @@
 // NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
-// RUN: %clang_cc1 -ffixed-point -triple x86_64-unknown-linux-gnu -S -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,SIGNED
-// RUN: %clang_cc1 -ffixed-point -triple x86_64-unknown-linux-gnu -S -emit-llvm %s -o - -fpadding-on-unsigned-fixed-point | FileCheck %s --check-prefixes=CHECK,UNSIGNED
+// RUN: %clang_cc1 -x c -ffixed-point -triple x86_64-unknown-linux-gnu -S -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,SIGNED
+// RUN: %clang_cc1 -x c -ffixed-point -triple x86_64-unknown-linux-gnu -S -emit-llvm %s -o - -fpadding-on-unsigned-fixed-point | FileCheck %s --check-prefixes=CHECK,UNSIGNED
+// RUN: %clang_cc1 -x c++ -ffixed-point -triple x86_64-unknown-linux-gnu -S -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,SIGNED
+// RUN: %clang_cc1 -x c++ -ffixed-point -triple x86_64-unknown-linux-gnu -S -emit-llvm %s -o - -fpadding-on-unsigned-fixed-point | FileCheck %s --check-prefixes=CHECK,UNSIGNED
+
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 short _Accum sa;
 _Accum a, a2;
@@ -994,3 +1000,7 @@ void float_sat5(void) {
 void float_sat6(void) {
   sat_uf = fl;
 }
+
+#ifdef __cplusplus
+}
+#endif