[clang][Interp] Don't abort on float div-by-zero

The result in that case can still be computed, and it's inf.

Author: tbaederr

clang/lib/AST/Interp/Interp.h

@@ -168,7 +168,8 @@ bool CheckDivRem(InterpState &S, CodePtr OpPC, const T &LHS, const T &RHS) {
     const auto *Op = cast<BinaryOperator>(S.Current->getExpr(OpPC));
     S.FFDiag(Op, diag::note_expr_divide_by_zero)
         << Op->getRHS()->getSourceRange();
-    return false;
+    if constexpr (!std::is_same_v<T, Floating>)
+      return false;
   }
 
   if (LHS.isSigned() && LHS.isMin() && RHS.isNegative() && RHS.isMinusOne()) {

clang/test/AST/Interp/c23.c

@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -std=c23 -fexperimental-new-constant-interpreter -verify=expected,both %s
+// RUN: %clang_cc1 -std=c23 -verify=ref,both %s
+
+
+
+const _Bool inf1 =  (1.0/0.0 == __builtin_inf());
+constexpr _Bool inf2 = (1.0/0.0 == __builtin_inf()); // both-error {{must be initialized by a constant expression}} \
+                                                     // both-note {{division by zero}}
+constexpr _Bool inf3 = __builtin_inf() == __builtin_inf();
+
+