[clang] f39af73 - [clang][Sema] Warn consecutive builtin comparisons in an expression (#92200)
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Fri May 17 06:29:25 PDT 2024
Author: Youngsuk Kim
Date: 2024-05-17T09:29:20-04:00
New Revision: f39af73f3edcc949bf9dc3535effc59afbcdda22
URL: https://github.com/llvm/llvm-project/commit/f39af73f3edcc949bf9dc3535effc59afbcdda22
DIFF: https://github.com/llvm/llvm-project/commit/f39af73f3edcc949bf9dc3535effc59afbcdda22.diff
LOG: [clang][Sema] Warn consecutive builtin comparisons in an expression (#92200)
Add warning under `-Wparentheses` for consistency with `gcc 14.1`.
Closes #20456
---------
Co-authored-by: Aaron Ballman <aaron at aaronballman.com>
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaExpr.cpp
clang/test/Sema/bool-compare.c
clang/test/Sema/parentheses.cpp
clang/test/SemaCXX/bool-compare.cpp
clang/test/SemaCXX/cxx2a-adl-only-template-id.cpp
clang/test/SemaTemplate/typo-dependent-name.cpp
clang/test/SemaTemplate/typo-template-name.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9799f878d7d72..85327576548cf 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -498,6 +498,9 @@ Improvements to Clang's diagnostics
}
};
+- Clang emits a ``-Wparentheses`` warning for expressions with consecutive comparisons like ``x < y < z``.
+ Fixes #GH20456.
+
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 59f44bc26eaf2..09b1874f9fddd 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6919,6 +6919,10 @@ def warn_precedence_bitwise_conditional : Warning<
def note_precedence_conditional_first : Note<
"place parentheses around the '?:' expression to evaluate it first">;
+def warn_consecutive_comparison : Warning<
+ "comparisons like 'X<=Y<=Z' don't have their mathematical meaning">,
+ InGroup<Parentheses>;
+
def warn_enum_constant_in_bool_context : Warning<
"converting the enum constant to a boolean">,
InGroup<IntInBoolContext>, DefaultIgnore;
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index e0aae6333e1a1..5ecfdee21f09d 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14867,6 +14867,11 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
case BO_GT:
ConvertHalfVec = true;
ResultTy = CheckCompareOperands(LHS, RHS, OpLoc, Opc);
+
+ if (const auto *BI = dyn_cast<BinaryOperator>(LHSExpr);
+ BI && BI->isComparisonOp())
+ Diag(OpLoc, diag::warn_consecutive_comparison);
+
break;
case BO_EQ:
case BO_NE:
diff --git a/clang/test/Sema/bool-compare.c b/clang/test/Sema/bool-compare.c
index 923ff4208e8be..2308dc4bf2bb2 100644
--- a/clang/test/Sema/bool-compare.c
+++ b/clang/test/Sema/bool-compare.c
@@ -85,7 +85,7 @@ void f(int x, int y, int z) {
if ((a<y) != -1) {}// expected-warning {{comparison of constant -1 with boolean expression is always true}}
if ((a<y) == z) {} // no warning
- if (a>y<z) {} // no warning
+ if (a>y<z) {} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
if ((a<y) > z) {} // no warning
if((a<y)>(z<y)) {} // no warning
if((a<y)==(z<y)){} // no warning
@@ -145,7 +145,7 @@ void f(int x, int y, int z) {
if (-1 !=(a<y)) {} // expected-warning {{comparison of constant -1 with boolean expression is always true}}
if (z ==(a<y)) {} // no warning
- if (z<a>y) {} // no warning
+ if (z<a>y) {} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
if (z > (a<y)) {} // no warning
if((z<y)>(a<y)) {} // no warning
if((z<y)==(a<y)){} // no warning
diff --git a/clang/test/Sema/parentheses.cpp b/clang/test/Sema/parentheses.cpp
index 324d9b5f1e414..e991cee16b0e2 100644
--- a/clang/test/Sema/parentheses.cpp
+++ b/clang/test/Sema/parentheses.cpp
@@ -215,3 +215,14 @@ namespace PR20735 {
// fix-it:"{{.*}}":{[[@LINE-9]]:20-[[@LINE-9]]:20}:")"
}
}
+
+void consecutive_builtin_compare(int x, int y, int z) {
+ (void)(x < y < z); // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+ (void)(x < y > z); // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+ (void)(x < y <= z); // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+ (void)(x <= y > z); // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+ (void)((x < y) < z); // no-warning
+ (void)((x < y) >= z); // no-warning
+
+ // TODO: Also issue warning for consecutive comparisons that use overloaded comparison operators?
+}
diff --git a/clang/test/SemaCXX/bool-compare.cpp b/clang/test/SemaCXX/bool-compare.cpp
index fe47633bb23b6..4e33e076a7de4 100644
--- a/clang/test/SemaCXX/bool-compare.cpp
+++ b/clang/test/SemaCXX/bool-compare.cpp
@@ -98,7 +98,7 @@ void f(int x, int y, int z) {
if ((a<y) != -1) {}// expected-warning {{comparison of constant -1 with expression of type 'bool' is always true}}
if ((a<y) == z) {} // no warning
- if (a>y<z) {} // no warning
+ if (a>y<z) {} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
if ((a<y) > z) {} // no warning
if((a<y)>(z<y)) {} // no warning
if((a<y)==(z<y)){} // no warning
@@ -159,7 +159,7 @@ void f(int x, int y, int z) {
if (-1 !=(a<y)) {} // expected-warning {{comparison of constant -1 with expression of type 'bool' is always true}}
if (z ==(a<y)) {} // no warning
- if (z<a>y) {} // no warning
+ if (z<a>y) {} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
if (z > (a<y)) {} // no warning
if((z<y)>(a<y)) {} // no warning
if((z<y)==(a<y)){} // no warning
diff --git a/clang/test/SemaCXX/cxx2a-adl-only-template-id.cpp b/clang/test/SemaCXX/cxx2a-adl-only-template-id.cpp
index 28ecbade1b1a9..b8397f41febc3 100644
--- a/clang/test/SemaCXX/cxx2a-adl-only-template-id.cpp
+++ b/clang/test/SemaCXX/cxx2a-adl-only-template-id.cpp
@@ -27,7 +27,7 @@ int e = h<0>(q); // ok, found by unqualified lookup
void fn() {
f<0>(q);
int f;
- f<0>(q); // expected-error {{invalid operands to binary expression}}
+ f<0>(q); // expected-error {{invalid operands to binary expression}} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
}
void disambig() {
diff --git a/clang/test/SemaTemplate/typo-dependent-name.cpp b/clang/test/SemaTemplate/typo-dependent-name.cpp
index 88b2fc373b1f5..fb61b03e50109 100644
--- a/clang/test/SemaTemplate/typo-dependent-name.cpp
+++ b/clang/test/SemaTemplate/typo-dependent-name.cpp
@@ -20,11 +20,11 @@ struct X : Base<T> {
bool f(T other) {
// A pair of comparisons; 'inner' is a dependent name so can't be assumed
// to be a template.
- return this->inner < other > ::z;
+ return this->inner < other > ::z; // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
}
};
-void use_x(X<int> x) { x.f(0); }
+void use_x(X<int> x) { x.f(0); } // expected-note {{requested here}}
template<typename T>
struct Y {
diff --git a/clang/test/SemaTemplate/typo-template-name.cpp b/clang/test/SemaTemplate/typo-template-name.cpp
index fe5201a8e26c3..741aa708e81fc 100644
--- a/clang/test/SemaTemplate/typo-template-name.cpp
+++ b/clang/test/SemaTemplate/typo-template-name.cpp
@@ -36,7 +36,7 @@ namespace InExpr {
// These are valid expressions.
foo<foo; // expected-warning {{self-comparison}}
- foo<int()>(0);
+ foo<int()>(0); // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
foo<int(), true>(false);
foo<Base{}.n;
}
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