Implement a warning for known shift overflows on constant shift

expressions. Consider the code:

  int64_t i = 10 << 30;

This compiles fine, but most developers expect it to produce the value
for 10 gigs, not -2 gigs. This is actually undefined behavior because
the LHS is a signed integer type.

The warning is currently gated behind -Wshift-overflow.

There is a special case where only the sign bit is overridden that gets
a custom error message and is by default ignored. This case is much less
likely to cause observed buggy behavior, it's just undefined behavior
according to the spec. This warning can be enabled with
-Wshift-sign-overflow.

Original patch by Oleg Slezberg, with style tweaks and some correctness
fixes by me.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126342 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index df327e7e5097177e8d2674c38d113a57e6c210be..d1e127b22bd60c90ddd3e57c404039f66099e95e 100644 (file)
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2340,6 +2340,14 @@ def warn_division_by_zero : Warning<"division by zero is undefined">;
 def warn_remainder_by_zero : Warning<"remainder by zero is undefined">;
 def warn_shift_negative : Warning<"shift count is negative">;
 def warn_shift_gt_typewidth : Warning<"shift count >= width of type">;
+def warn_shift_result_gt_typewidth : Warning<
+  "shift result (%0) requires %1 bits to represent, but the promoted type of "
+  "the shift expression is %2 with only %3 bits">,
+   InGroup<DiagGroup<"shift-overflow">>;
+def warn_shift_result_overrides_sign_bit : Warning<
+  "shift result (%0) overrides the sign bit of the promoted type of the shift "
+  "expression (%1) and becomes negative">,
+  InGroup<DiagGroup<"shift-sign-overflow">>, DefaultIgnore;
 
 def warn_precedence_bitwise_rel : Warning<
   "%0 has lower precedence than %1; %1 will be evaluated first">,

diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 6b74b863a8c1a7691c5a2ca76224160feceec39e..1cc20b60f79e4077d56ac3aad650ffe7c71f9109 100644 (file)
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -4790,7 +4790,8 @@ public:
   QualType CheckSubtractionOperands( // C99 6.5.6
     Expr *&lex, Expr *&rex, SourceLocation OpLoc, QualType* CompLHSTy = 0);
   QualType CheckShiftOperands( // C99 6.5.7
-    Expr *&lex, Expr *&rex, SourceLocation OpLoc, bool isCompAssign = false);
+    Expr *&lex, Expr *&rex, SourceLocation OpLoc, unsigned Opc,
+    bool isCompAssign = false);
   QualType CheckCompareOperands( // C99 6.5.8/9
     Expr *&lex, Expr *&rex, SourceLocation OpLoc, unsigned Opc,
                                 bool isRelational);

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 1ba8ea62b4165a2041ee14503eb189f549351ef3..076ffeb26878303ec4c2cc1dfc36867062cda0ce 100644 (file)
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -6626,9 +6626,61 @@ static bool isScopedEnumerationType(QualType T) {
   return false;
 }
 
+static void DiagnoseBadShiftValues(Sema& S, Expr *&lex, Expr *&rex,
+                                   SourceLocation Loc, unsigned Opc,
+                                   QualType LHSTy) {
+  llvm::APSInt Right;
+  // Check right/shifter operand
+  if (rex->isValueDependent() || !rex->isIntegerConstantExpr(Right, S.Context))
+    return;
+
+  if (Right.isNegative()) {
+    S.Diag(Loc, diag::warn_shift_negative) << rex->getSourceRange();
+    return;
+  }
+  llvm::APInt LeftBits(Right.getBitWidth(),
+                       S.Context.getTypeSize(lex->getType()));
+  if (Right.uge(LeftBits)) {
+    S.Diag(Loc, diag::warn_shift_gt_typewidth) << rex->getSourceRange();
+    return;
+  }
+  if (Opc != BO_Shl)
+    return;
+
+  // When left shifting an ICE which is signed, we can check for overflow which
+  // according to C++ has undefined behavior ([expr.shift] 5.8/2). Unsigned
+  // integers have defined behavior modulo one more than the maximum value
+  // representable in the result type, so never warn for those.
+  llvm::APSInt Left;
+  if (!lex->isIntegerConstantExpr(Left, S.Context) ||
+      LHSTy->hasUnsignedIntegerRepresentation())
+    return;
+  llvm::APInt ResultBits =
+      static_cast<llvm::APInt&>(Right) + Left.getMinSignedBits();
+  if (LeftBits.uge(ResultBits))
+    return;
+  llvm::APSInt Result = Left.extend(ResultBits.getLimitedValue());
+  Result = Result.shl(Right);
+
+  // If we are only missing a sign bit, this is less likely to result in actual
+  // bugs -- if the result is cast back to an unsigned type, it will have the
+  // expected value. Thus we place this behind a different warning that can be
+  // turned off separately if needed.
+  if (LeftBits == ResultBits - 1) {
+    S.Diag(Loc, diag::warn_shift_result_overrides_sign_bit)
+        << Result.toString(10) << LHSTy
+        << lex->getSourceRange() << rex->getSourceRange();
+    return;
+  }
+
+  S.Diag(Loc, diag::warn_shift_result_gt_typewidth)
+    << Result.toString(10) << Result.getMinSignedBits() << LHSTy
+    << Left.getBitWidth() << lex->getSourceRange() << rex->getSourceRange();
+}
+
 // C99 6.5.7
 QualType Sema::CheckShiftOperands(Expr *&lex, Expr *&rex, SourceLocation Loc,
-                                  bool isCompAssign) {
+                                  unsigned Opc, bool isCompAssign) {
   // C99 6.5.7p2: Each of the operands shall have integer type.
   if (!lex->getType()->hasIntegerRepresentation() || 
       !rex->getType()->hasIntegerRepresentation())
@@ -6659,19 +6711,7 @@ QualType Sema::CheckShiftOperands(Expr *&lex, Expr *&rex, SourceLocation Loc,
   UsualUnaryConversions(rex);
 
   // Sanity-check shift operands
-  llvm::APSInt Right;
-  // Check right/shifter operand
-  if (!rex->isValueDependent() &&
-      rex->isIntegerConstantExpr(Right, Context)) {
-    if (Right.isNegative())
-      Diag(Loc, diag::warn_shift_negative) << rex->getSourceRange();
-    else {
-      llvm::APInt LeftBits(Right.getBitWidth(),
-                          Context.getTypeSize(lex->getType()));
-      if (Right.uge(LeftBits))
-        Diag(Loc, diag::warn_shift_gt_typewidth) << rex->getSourceRange();
-    }
-  }
+  DiagnoseBadShiftValues(*this, lex, rex, Loc, Opc, LHSTy);
 
   // "The type of the result is that of the promoted left operand."
   return LHSTy;
@@ -7958,7 +7998,7 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
     break;
   case BO_Shl:
   case BO_Shr:
-    ResultTy = CheckShiftOperands(lhs, rhs, OpLoc);
+    ResultTy = CheckShiftOperands(lhs, rhs, OpLoc, Opc);
     break;
   case BO_LE:
   case BO_LT:
@@ -8005,7 +8045,7 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
     break;
   case BO_ShlAssign:
   case BO_ShrAssign:
-    CompResultTy = CheckShiftOperands(lhs, rhs, OpLoc, true);
+    CompResultTy = CheckShiftOperands(lhs, rhs, OpLoc, Opc, true);
     CompLHSTy = CompResultTy;
     if (!CompResultTy.isNull())
       ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);

diff --git a/test/Analysis/retain-release-basic-store.m b/test/Analysis/retain-release-basic-store.m
index 751dca0ce30b4c0b518e566877b142c72639d5c6..8c05efef66ee388f68b25d00019cf44e158bccdb 100644 (file)
--- a/test/Analysis/retain-release-basic-store.m
+++ b/test/Analysis/retain-release-basic-store.m
@@ -69,7 +69,7 @@ extern DADiskRef DADiskCopyWholeDisk( DADiskRef disk );
 @interface NSAppleEventManager : NSObject {
 }
 @end enum {
-kDAReturnSuccess = 0,     kDAReturnError = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
+kDAReturnSuccess = 0,     kDAReturnError = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
 typedef mach_error_t DAReturn;
 typedef const struct __DADissenter * DADissenterRef;
 extern DADissenterRef DADissenterCreate( CFAllocatorRef allocator, DAReturn status, CFStringRef string );

diff --git a/test/Analysis/retain-release-gc-only.m b/test/Analysis/retain-release-gc-only.m
index 6f1dd92df9971cd95fd0e850204045f8857327af..7d7c58fbcd5147c4419c6305a66773dd19fdf2d2 100644 (file)
--- a/test/Analysis/retain-release-gc-only.m
+++ b/test/Analysis/retain-release-gc-only.m
@@ -189,7 +189,7 @@ CVTimeStamp;
 }
 typedef int CIFormat;
 @end  enum {
-kDAReturnSuccess = 0,     kDAReturnError = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
+kDAReturnSuccess = 0,     kDAReturnError = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
 typedef mach_error_t DAReturn;
 typedef const struct __DADissenter * DADissenterRef;
 extern DADissenterRef DADissenterCreate( CFAllocatorRef allocator, DAReturn status, CFStringRef string );

diff --git a/test/Analysis/retain-release-region-store.m b/test/Analysis/retain-release-region-store.m
index 05b91fcf5c567e60d373d855a8c85f47c4e00dec..ec765e3fe809aad3bb890268667ccb77bd978bca 100644 (file)
--- a/test/Analysis/retain-release-region-store.m
+++ b/test/Analysis/retain-release-region-store.m
@@ -75,7 +75,7 @@ extern DADiskRef DADiskCopyWholeDisk( DADiskRef disk );
 @interface NSAppleEventManager : NSObject {
 }
 @end enum {
-kDAReturnSuccess = 0,     kDAReturnError = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
+kDAReturnSuccess = 0,     kDAReturnError = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
 typedef mach_error_t DAReturn;
 typedef const struct __DADissenter * DADissenterRef;
 extern DADissenterRef DADissenterCreate( CFAllocatorRef allocator, DAReturn status, CFStringRef string );

diff --git a/test/Analysis/retain-release.m b/test/Analysis/retain-release.m
index 81e015f5fc44702a0d85caaf84b852cddf417f70..71e1620aa534c16e56be4e1a8176372069b59634 100644 (file)
--- a/test/Analysis/retain-release.m
+++ b/test/Analysis/retain-release.m
@@ -217,7 +217,7 @@ CVTimeStamp;
 }
 typedef int CIFormat;
 @end  enum {
-kDAReturnSuccess = 0,     kDAReturnError = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
+kDAReturnSuccess = 0,     kDAReturnError = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
 typedef mach_error_t DAReturn;
 typedef const struct __DADissenter * DADissenterRef;
 extern DADissenterRef DADissenterCreate( CFAllocatorRef allocator, DAReturn status, CFStringRef string );

diff --git a/test/Sema/shift.c b/test/Sema/shift.c
index 4273cab98ee39b23a547b3372435ca896aa032ab..63c97fe7b029b25368828c3d3ecccaad86b07cd1 100644 (file)
--- a/test/Sema/shift.c
+++ b/test/Sema/shift.c
@@ -1,7 +1,9 @@
-// RUN: %clang -Wall -ffreestanding -fsyntax-only -Xclang -verify %s
+// RUN: %clang -Wall -Wshift-sign-overflow -ffreestanding -fsyntax-only -Xclang -verify %s
 
 #include <limits.h>
 
+#define WORD_BIT (sizeof(int) * CHAR_BIT)
+
 enum {
   X = 1 << 0,
   Y = 1 << 1,
@@ -32,6 +34,22 @@ void test() {
   c <<= CHAR_BIT+1; // expected-warning {{shift count >= width of type}}
   c >>= CHAR_BIT+1; // expected-warning {{shift count >= width of type}}
   (void)((long)c << CHAR_BIT);
+
+  int i;
+  i = 1 << (WORD_BIT - 2);
+  i = 2 << (WORD_BIT - 1); // expected-warning {{the promoted type of the shift expression is 'int'}}
+  i = 1 << (WORD_BIT - 1); // expected-warning {{overrides the sign bit of the promoted type of the shift expression ('int')}}
+  i = -1 << (WORD_BIT - 1);
+  i = 0 << (WORD_BIT - 1);
+  i = (char)1 << (WORD_BIT - 2);
+
+  unsigned u;
+  u = 1U << (WORD_BIT - 1);
+  u = 5U << (WORD_BIT - 1);
+
+  long long int lli;
+  lli = INT_MIN << 2; // expected-warning {{the promoted type of the shift expression is 'int'}}
+  lli = 1LL << (sizeof(long long) * CHAR_BIT - 2);
 }
 
 #define a 0