[PATCH] D24861: [Sema] extend Wshift-op-parentheses so it warns for multiplicative operators

[Daniel Marjamäki via cfe-commits]

danielmarjamaki created this revision.
danielmarjamaki added reviewers: dblaikie, rtrieu.
danielmarjamaki added a subscriber: cfe-commits.
danielmarjamaki set the repository for this revision to rL LLVM.

This patch makes Clang warn about following code:

    a = (b * c >> 2);

It might be a good idea to use parentheses to clarify the operator precedence.


Repository:
  rL LLVM

https://reviews.llvm.org/D24861

Files:
  lib/Sema/SemaExpr.cpp
  test/Sema/parentheses.cpp

Index: test/Sema/parentheses.cpp
===================================================================
--- test/Sema/parentheses.cpp
+++ test/Sema/parentheses.cpp
@@ -95,6 +95,21 @@
   // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:10-[[@LINE-2]]:10}:"("
   // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:15-[[@LINE-3]]:15}:")"
 
+  (void)(a >> b * c); // expected-warning {{operator '>>' has lower precedence than '*'; '*' will be evaluated first}} \
+                         expected-note {{place parentheses around the '*' expression to silence this warning}}
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:15-[[@LINE-2]]:15}:"("
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:20-[[@LINE-3]]:20}:")"
+
+  (void)(a / b << c); // expected-warning {{operator '<<' has lower precedence than '/'; '/' will be evaluated first}} \
+                         expected-note {{place parentheses around the '/' expression to silence this warning}}
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:10-[[@LINE-2]]:10}:"("
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:15-[[@LINE-3]]:15}:")"
+
+  (void)(a % b << c); // expected-warning {{operator '<<' has lower precedence than '%'; '%' will be evaluated first}} \
+                         expected-note {{place parentheses around the '%' expression to silence this warning}}
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:10-[[@LINE-2]]:10}:"("
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:15-[[@LINE-3]]:15}:")"
+
   Stream() << b + c;
   Stream() >> b + c; // expected-warning {{operator '>>' has lower precedence than '+'; '+' will be evaluated first}} \
                         expected-note {{place parentheses around the '+' expression to silence this warning}}
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -11246,10 +11246,10 @@
   }
 }
 
-static void DiagnoseAdditionInShift(Sema &S, SourceLocation OpLoc,
+static void DiagnoseAddOrMulInShift(Sema &S, SourceLocation OpLoc,
                                     Expr *SubExpr, StringRef Shift) {
   if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(SubExpr)) {
-    if (Bop->getOpcode() == BO_Add || Bop->getOpcode() == BO_Sub) {
+    if (Bop->isAdditiveOp() || Bop->isMultiplicativeOp()) {
       StringRef Op = Bop->getOpcodeStr();
       S.Diag(Bop->getOperatorLoc(), diag::warn_addition_in_bitshift)
           << Bop->getSourceRange() << OpLoc << Shift << Op;
@@ -11313,8 +11313,8 @@
   if ((Opc == BO_Shl && LHSExpr->getType()->isIntegralType(Self.getASTContext()))
       || Opc == BO_Shr) {
     StringRef Shift = BinaryOperator::getOpcodeStr(Opc);
-    DiagnoseAdditionInShift(Self, OpLoc, LHSExpr, Shift);
-    DiagnoseAdditionInShift(Self, OpLoc, RHSExpr, Shift);
+    DiagnoseAddOrMulInShift(Self, OpLoc, LHSExpr, Shift);
+    DiagnoseAddOrMulInShift(Self, OpLoc, RHSExpr, Shift);
   }
 
   // Warn on overloaded shift operators and comparisons, such as:


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D24861.72262.patch
Type: text/x-patch
Size: 2928 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20160923/19976d55/attachment-0001.bin>