[clang] Emit bad shift warnings

Author: budimirarandjelovichtec

clang/lib/AST/ExprConstant.cpp

@@ -2856,6 +2856,9 @@ static bool handleIntIntBinOp(EvalInfo &Info, const BinaryOperator *E,
       else if (LHS.countl_zero() < SA)
         Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
     }
+    if (Info.EvalStatus.Diag && !Info.EvalStatus.Diag->empty() &&
+        Info.getLangOpts().CPlusPlus)
+      return false;
     Result = LHS << SA;
     return true;
   }
@@ -2879,6 +2882,10 @@ static bool handleIntIntBinOp(EvalInfo &Info, const BinaryOperator *E,
     if (SA != RHS)
       Info.CCEDiag(E, diag::note_constexpr_large_shift)
         << RHS << E->getType() << LHS.getBitWidth();
+
+    if (Info.EvalStatus.Diag && !Info.EvalStatus.Diag->empty() &&
+        Info.getLangOpts().CPlusPlus)
+      return false;
     Result = LHS >> SA;
     return true;
   }

clang/lib/Sema/SemaExpr.cpp

@@ -11246,7 +11246,7 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
   if (Right.isNegative()) {
     S.DiagRuntimeBehavior(Loc, RHS.get(),
                           S.PDiag(diag::warn_shift_negative)
-                            << RHS.get()->getSourceRange());
+                              << RHS.get()->getSourceRange());
     return;
   }
 
@@ -11261,7 +11261,7 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
   if (Right.uge(LeftSize)) {
     S.DiagRuntimeBehavior(Loc, RHS.get(),
                           S.PDiag(diag::warn_shift_gt_typewidth)
-                            << RHS.get()->getSourceRange());
+                              << RHS.get()->getSourceRange());
     return;
   }
 
@@ -11294,7 +11294,7 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
   if (Left.isNegative()) {
     S.DiagRuntimeBehavior(Loc, LHS.get(),
                           S.PDiag(diag::warn_shift_lhs_negative)
-                            << LHS.get()->getSourceRange());
+                              << LHS.get()->getSourceRange());
     return;
   }
 
@@ -17130,11 +17130,20 @@ Sema::VerifyIntegerConstantExpression(Expr *E, llvm::APSInt *Result,
   // Circumvent ICE checking in C++11 to avoid evaluating the expression twice
   // in the non-ICE case.
   if (!getLangOpts().CPlusPlus11 && E->isIntegerConstantExpr(Context)) {
+    SmallVector<PartialDiagnosticAt, 8> Notes;
     if (Result)
-      *Result = E->EvaluateKnownConstIntCheckOverflow(Context);
+      *Result = E->EvaluateKnownConstIntCheckOverflow(Context, &Notes);
     if (!isa<ConstantExpr>(E))
       E = Result ? ConstantExpr::Create(Context, E, APValue(*Result))
                  : ConstantExpr::Create(Context, E);
+
+    if (Notes.size() && !Diagnoser.Suppress) {
+      Diagnoser.diagnoseNotICE(*this, DiagLoc) << E->getSourceRange();
+      for (const PartialDiagnosticAt &Note : Notes)
+        Diag(Note.first, Note.second);
+      return ExprError();
+    }
+
     return E;
   }
 

clang/test/C/drs/dr0xx.c

@@ -430,7 +430,7 @@ void dr081(void) {
   /* Demonstrate that we don't crash when left shifting a signed value; that's
    * implementation defined behavior.
    */
- _Static_assert(-1 << 1 == -2, "fail"); /* Didn't shift a zero into the "sign bit". */
+ _Static_assert(-1 << 1 == -2, "fail"); /* Undefined behavior since C99 */
  _Static_assert(1 << 3 == 1u << 3u, "fail"); /* Shift of a positive signed value does sensible things. */
 }
 

clang/test/Sema/shift-count-negative.c

@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify=expected,c -Wshift-count-negative %s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify=expected,c -Wall %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify=expected,cpp -Wshift-count-negative %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify=expected,cpp -Wall %s
+
+enum shiftof {
+    X = (1<<-29) // c-error {{expression is not an integer constant expression}}
+                 // cpp-error@-1 {{expression is not an integral constant expression}}
+                 // expected-note@-2 {{negative shift count -29}}
+};

clang/test/Sema/shift-count-overflow.c

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wshift-count-overflow %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wall %s
+
+enum shiftof {
+    X = (1<<32) // expected-error {{expression is not an integer constant expression}}
+                // expected-note@-1 {{shift count 32 >= width of type 'int'}}
+};

clang/test/Sema/shift-negative-value.c

@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify=expected,c -Wshift-negative-value %s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify=expected,c -Wall %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify=expected,cpp -Wshift-negative-value %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify=expected,cpp -Wall %s
+
+enum shiftof {
+    X = (-1<<29) // c-error {{expression is not an integer constant expression}}
+                 // cpp-error@-1 {{expression is not an integral constant expression}}
+                 // expected-note@-2 {{left shift of negative value -1}}
+};

clang/test/Sema/vla-2.c

@@ -4,11 +4,13 @@
 // a different codepath when we have already emitted an error.)
 
 int PotentiallyEvaluatedSizeofWarn(int n) {
-  return (int)sizeof *(0 << 32,(int(*)[n])0); // expected-warning {{left operand of comma operator has no effect}} expected-warning {{shift count >= width of type}}
+  return (int)sizeof *(0 << 32,(int(*)[n])0); /* expected-warning {{shift count >= width of type}}
+                                                 expected-warning {{left operand of comma operator has no effect}} */
 }
 
 void PotentiallyEvaluatedTypeofWarn(int n) {
-  __typeof(*(0 << 32,(int(*)[n])0)) x; // expected-warning {{left operand of comma operator has no effect}} expected-warning {{shift count >= width of type}}
+  __typeof(*(0 << 32,(int(*)[n])0)) x; /* expected-warning {{shift count >= width of type}}
+                                          expected-warning {{left operand of comma operator has no effect}} */
   (void)x;
 }
 

clang/test/SemaCXX/shift.cpp

@@ -22,7 +22,6 @@ void test() {
   c = 1 << -1; // expected-warning {{shift count is negative}}
   c = 1 >> -1; // expected-warning {{shift count is negative}}
   c = 1 << (unsigned)-1; // expected-warning {{shift count >= width of type}}
-                         // expected-warning@-1 {{implicit conversion}}
   c = 1 >> (unsigned)-1; // expected-warning {{shift count >= width of type}}
   c = 1 << c;
   c <<= 0;