[clang] [clang] Emit bad shift warnings (PR #70307)
Budimir Aranđelović via cfe-commits
cfe-commits at lists.llvm.org
Tue Mar 26 03:42:28 PDT 2024
https://github.com/budimirarandjelovicsyrmia updated https://github.com/llvm/llvm-project/pull/70307
>From 17fb77d094018db20de0ac2a65861338006f9d68 Mon Sep 17 00:00:00 2001
From: budimirarandjelovicsyrmia <budimir.arandjelovic at syrmia.com>
Date: Thu, 26 Oct 2023 10:39:52 +0200
Subject: [PATCH] [clang] Emit bad shift warnings
---
clang/lib/Sema/SemaExpr.cpp | 29 +++++++++++++++-------
clang/test/AST/Interp/shifts.cpp | 7 ++----
clang/test/C/drs/dr0xx.c | 2 +-
clang/test/Sema/shift-count-negative.c | 8 ++++++
clang/test/Sema/shift-count-overflow.c | 6 +++++
clang/test/Sema/shift-negative-value.c | 8 ++++++
clang/test/Sema/vla-2.c | 9 ++++---
clang/test/SemaCXX/cxx2a-explicit-bool.cpp | 2 +-
clang/test/SemaCXX/shift.cpp | 1 -
9 files changed, 52 insertions(+), 20 deletions(-)
create mode 100644 clang/test/Sema/shift-count-negative.c
create mode 100644 clang/test/Sema/shift-count-overflow.c
create mode 100644 clang/test/Sema/shift-negative-value.c
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 94f52004cf6c27..4fef5163c657f8 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -11444,9 +11444,12 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
llvm::APSInt Right = RHSResult.Val.getInt();
if (Right.isNegative()) {
- S.DiagRuntimeBehavior(Loc, RHS.get(),
- S.PDiag(diag::warn_shift_negative)
- << RHS.get()->getSourceRange());
+ if (S.ExprEvalContexts.back().isConstantEvaluated())
+ S.Diag(Loc, diag::warn_shift_negative) << RHS.get()->getSourceRange();
+ else
+ S.DiagRuntimeBehavior(Loc, RHS.get(),
+ S.PDiag(diag::warn_shift_negative)
+ << RHS.get()->getSourceRange());
return;
}
@@ -11460,9 +11463,14 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
}
llvm::APInt LeftBits(Right.getBitWidth(), LeftSize);
if (Right.uge(LeftBits)) {
- S.DiagRuntimeBehavior(Loc, RHS.get(),
- S.PDiag(diag::warn_shift_gt_typewidth)
- << RHS.get()->getSourceRange());
+ if (S.ExprEvalContexts.back().isConstantEvaluated()
+ && !S.getLangOpts().CPlusPlus11)
+ S.Diag(Loc, diag::warn_shift_gt_typewidth)
+ << RHS.get()->getSourceRange();
+ else
+ S.DiagRuntimeBehavior(Loc, RHS.get(),
+ S.PDiag(diag::warn_shift_gt_typewidth)
+ << RHS.get()->getSourceRange());
return;
}
@@ -11493,9 +11501,12 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
// If LHS does not have a non-negative value then, the
// behavior is undefined before C++2a. Warn about it.
if (Left.isNegative()) {
- S.DiagRuntimeBehavior(Loc, LHS.get(),
- S.PDiag(diag::warn_shift_lhs_negative)
- << LHS.get()->getSourceRange());
+ if (S.ExprEvalContexts.back().isConstantEvaluated())
+ S.Diag(Loc, diag::warn_shift_lhs_negative) << LHS.get()->getSourceRange();
+ else
+ S.DiagRuntimeBehavior(Loc, LHS.get(),
+ S.PDiag(diag::warn_shift_lhs_negative)
+ << LHS.get()->getSourceRange());
return;
}
diff --git a/clang/test/AST/Interp/shifts.cpp b/clang/test/AST/Interp/shifts.cpp
index b1df7b85cc9f2b..c11ba0f6f3a19e 100644
--- a/clang/test/AST/Interp/shifts.cpp
+++ b/clang/test/AST/Interp/shifts.cpp
@@ -33,13 +33,10 @@ namespace shifts {
// FIXME: 'implicit conversion' warning missing in the new interpreter. \
// cxx17-warning {{shift count >= width of type}} \
// ref-warning {{shift count >= width of type}} \
- // ref-warning {{implicit conversion}} \
- // ref-cxx17-warning {{shift count >= width of type}} \
- // ref-cxx17-warning {{implicit conversion}}
+ // ref-cxx17-warning {{shift count >= width of type}}
c = 1 >> (unsigned)-1; // expected-warning {{shift count >= width of type}} \
// cxx17-warning {{shift count >= width of type}} \
- // ref-warning {{shift count >= width of type}} \
- // ref-cxx17-warning {{shift count >= width of type}}
+ // ref-warning {{shift count >= width of type}}
c = 1 << c;
c <<= 0;
c >>= 0;
diff --git a/clang/test/C/drs/dr0xx.c b/clang/test/C/drs/dr0xx.c
index 6a3717f0729b60..6611b2b65264fa 100644
--- a/clang/test/C/drs/dr0xx.c
+++ b/clang/test/C/drs/dr0xx.c
@@ -426,7 +426,7 @@ 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. */
}
diff --git a/clang/test/Sema/shift-count-negative.c b/clang/test/Sema/shift-count-negative.c
new file mode 100644
index 00000000000000..af16332e0b0ee7
--- /dev/null
+++ b/clang/test/Sema/shift-count-negative.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wshift-count-negative %s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wall %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wshift-count-negative %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wall %s
+
+enum shiftof {
+ X = (1<<-29) // expected-warning {{shift count is negative}}
+};
diff --git a/clang/test/Sema/shift-count-overflow.c b/clang/test/Sema/shift-count-overflow.c
new file mode 100644
index 00000000000000..99803cdd8e5252
--- /dev/null
+++ b/clang/test/Sema/shift-count-overflow.c
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wshift-count-overflow %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wall %s
+
+enum shiftof {
+ X = (1<<32) // expected-warning {{shift count >= width of type}}
+};
diff --git a/clang/test/Sema/shift-negative-value.c b/clang/test/Sema/shift-negative-value.c
new file mode 100644
index 00000000000000..ce6c5f2c5c419e
--- /dev/null
+++ b/clang/test/Sema/shift-negative-value.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wshift-negative-value %s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wall %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wshift-negative-value %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wall %s
+
+enum shiftof {
+ X = (-1<<29) // expected-warning {{shifting a negative signed value is undefined}}
+};
diff --git a/clang/test/Sema/vla-2.c b/clang/test/Sema/vla-2.c
index 316931f2706077..140dd4facb7464 100644
--- a/clang/test/Sema/vla-2.c
+++ b/clang/test/Sema/vla-2.c
@@ -4,14 +4,17 @@
// 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;
}
void PotentiallyEvaluatedArrayBoundWarn(int n) {
- (void)*(int(*)[(0 << 32,n)])0; // expected-warning {{left operand of comma operator has no effect}}
+ (void)*(int(*)[(0 << 32,n)])0; /* expected-warning {{shift count >= width of type}}
+ expected-warning {{left operand of comma operator has no effect}} */
}
diff --git a/clang/test/SemaCXX/cxx2a-explicit-bool.cpp b/clang/test/SemaCXX/cxx2a-explicit-bool.cpp
index ad2a3a1ea75e9f..16b23348197e37 100644
--- a/clang/test/SemaCXX/cxx2a-explicit-bool.cpp
+++ b/clang/test/SemaCXX/cxx2a-explicit-bool.cpp
@@ -21,7 +21,7 @@ namespace special_cases
template<int a>
struct A {
// expected-note at -1+ {{candidate constructor}}
- explicit(1 << a)
+ explicit(1 << a) // expected-warning {{shift count is negative}}
// expected-note at -1 {{negative shift count -1}}
// expected-error at -2 {{explicit specifier argument is not a constant expression}}
A(int);
diff --git a/clang/test/SemaCXX/shift.cpp b/clang/test/SemaCXX/shift.cpp
index 89a98791d3eba7..c3249b124e926a 100644
--- a/clang/test/SemaCXX/shift.cpp
+++ b/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 at -1 {{implicit conversion}}
c = 1 >> (unsigned)-1; // expected-warning {{shift count >= width of type}}
c = 1 << c;
c <<= 0;
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