[clang] fix divide by zero in ComplexExprEvaluator (#104666)

fix: #55390.

---------

Co-authored-by: Sergei Barannikov <[email protected]>

Author: c8ef

clang/docs/ReleaseNotes.rst

@@ -274,6 +274,8 @@ Bug Fixes to C++ Support
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
+- Fixed a crash that occurred when dividing by zero in complex integer division. (#GH55390).
+
 Miscellaneous Bug Fixes
 ^^^^^^^^^^^^^^^^^^^^^^^
 

clang/lib/AST/ExprConstant.cpp

@@ -15615,12 +15615,12 @@ bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
         HandleComplexComplexDiv(A, B, C, D, ResR, ResI);
       }
     } else {
-      if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0)
-        return Error(E, diag::note_expr_divide_by_zero);
-
       ComplexValue LHS = Result;
       APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() +
         RHS.getComplexIntImag() * RHS.getComplexIntImag();
+      if (Den.isZero())
+        return Error(E, diag::note_expr_divide_by_zero);
+
       Result.getComplexIntReal() =
         (LHS.getComplexIntReal() * RHS.getComplexIntReal() +
          LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den;

clang/test/SemaCXX/constant-expression-cxx11.cpp

@@ -1268,6 +1268,9 @@ constexpr complex_wrap makeComplexWrap(int re, int im) {
 static_assert(makeComplexWrap(1,0) == complex(1), "");
 static_assert(makeComplexWrap(1,0) != complex(0, 1), "");
 
+constexpr auto GH55390 = 1 / 65536j; // expected-note {{division by zero}} \
+                                     // expected-error {{constexpr variable 'GH55390' must be initialized by a constant expression}} \
+                                     // expected-warning {{imaginary constants are a GNU extension}}
 }
 
 namespace PR11595 {