https://github.com/JOE1994 created
https://github.com/llvm/llvm-project/pull/92200
Made the following decisions for consistency with `gcc 14.1`:
* Add warning under -Wparentheses
* Set the warning to DefaultIgnore, although -Wparentheses is enabled by default
* This warning is only issued when -Wparentheses is explicitly enabled (via
-Wparentheses or -Wall)
Closes #20456
>From 2c7f9a083c129df70a79d019286b6a29643a8973 Mon Sep 17 00:00:00 2001
From: Youngsuk Kim <youngsuk....@hpe.com>
Date: Tue, 14 May 2024 17:42:59 -0500
Subject: [PATCH] [clang][Sema] Warn consecutive builtin comparisons in an
expression
Made the following decisions for consistency with `gcc 14.1`:
* Add warning under -Wparentheses
* Set the warning to DefaultIgnore, although -Wparentheses is enabled by default
* This warning is only issued when -Wparentheses is explicitly enabled
(via -Wparentheses or -Wall)
Closes #20456
---
clang/docs/ReleaseNotes.rst | 3 +++
clang/include/clang/Basic/DiagnosticSemaKinds.td | 4 ++++
clang/lib/Sema/SemaExpr.cpp | 5 +++++
clang/test/Sema/parentheses.cpp | 7 +++++++
4 files changed, 19 insertions(+)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index ae699ebfc6038..13d58e69aeeb7 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -487,6 +487,9 @@ Improvements to Clang's diagnostics
}
};
+- Clang emits a ``-Wparentheses`` warning for expressions with consecutive
comparisons like ``x < y < z``.
+ It was made a ``-Wparentheses`` warning to be consistent with gcc.
+
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 6100fba510059..612043f410890 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6911,6 +6911,10 @@ 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>, DefaultIgnore;
+
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 ec84798e4ce60..fab34f4fa3e14 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14878,6 +14878,11 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation
OpLoc,
case BO_GT:
ConvertHalfVec = true;
ResultTy = CheckCompareOperands(LHS, RHS, OpLoc, Opc);
+
+ if (const auto *BI = dyn_cast<BinaryOperator>(LHSExpr))
+ if (BI->isComparisonOp())
+ Diag(OpLoc, diag::warn_consecutive_comparison);
+
break;
case BO_EQ:
case BO_NE:
diff --git a/clang/test/Sema/parentheses.cpp b/clang/test/Sema/parentheses.cpp
index 324d9b5f1e414..8e546461fb643 100644
--- a/clang/test/Sema/parentheses.cpp
+++ b/clang/test/Sema/parentheses.cpp
@@ -215,3 +215,10 @@ 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}}
+}
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