[ExprConstant] Handle compound assignment when LHS has integral type and RHS has floating point type

Fixes PR39858

Differential Revision: https://reviews.llvm.org/D55413

llvm-svn: 349444

2 files changed, 27 insertions, 7 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 837dc9c2a8e..2022b07bffe 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -3439,19 +3439,31 @@ struct CompoundAssignSubobjectHandler {
     if (!checkConst(SubobjType))
       return false;
 
-    if (!SubobjType->isIntegerType() || !RHS.isInt()) {
+    if (!SubobjType->isIntegerType()) {
       // We don't support compound assignment on integer-cast-to-pointer
       // values.
       Info.FFDiag(E);
       return false;
     }
 
-    APSInt LHS = HandleIntToIntCast(Info, E, PromotedLHSType,
-                                    SubobjType, Value);
-    if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
-      return false;
-    Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
-    return true;
+    if (RHS.isInt()) {
+      APSInt LHS =
+          HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
+      if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
+        return false;
+      Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
+      return true;
+    } else if (RHS.isFloat()) {
+      APFloat FValue(0.0);
+      return HandleIntToFloatCast(Info, E, SubobjType, Value, PromotedLHSType,
+                                  FValue) &&
+             handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
+             HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
+                                  Value);
+    }
+
+    Info.FFDiag(E);
+    return false;
   }
   bool found(APFloat &Value, QualType SubobjType) {
     return checkConst(SubobjType) &&
diff --git a/clang/test/SemaCXX/constant-expression-cxx1y.cpp b/clang/test/SemaCXX/constant-expression-cxx1y.cpp
index a71dbc0eb50..3c57ac573f2 100644
--- a/clang/test/SemaCXX/constant-expression-cxx1y.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx1y.cpp
@@ -356,6 +356,14 @@ namespace compound_assign {
     if (a != 13) return false;
     a &= 14;
     if (a != 12) return false;
+    a += -1.2;
+    if (a != 10) return false;
+    a -= 3.1;
+    if (a != 6) return false;
+    a *= 2.2;
+    if (a != 13) return false;
+    if (&(a /= 1.5) != &a) return false;
+    if (a != 8) return false;
     return true;
   }
   static_assert(test_int(), "");