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[Clang][diagnostics] Improve the diagnostics for chained comparisons #129285

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Merged
merged 3 commits into from
Mar 6, 2025
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[Clang][diagnostics] Improve the diagnostics for chained comparisons #129285

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[Clang][diagnostics] Improve the diagnostics for chained comparisons …
AmrDeveloper Feb 28, 2025
99197b6
Add issue number to release note
AmrDeveloper Mar 3, 2025
b0de9a9
Improve the error message
AmrDeveloper Mar 5, 2025
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2 changes: 2 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Expand Up @@ -220,6 +220,8 @@ Improvements to Clang's diagnostics
:doc:`ThreadSafetyAnalysis` still does not perform alias analysis. The
feature will be default-enabled with ``-Wthread-safety`` in a future release.

- Improve the diagnostics for chained comparisons to report actual expressions and operators (#GH129069).

- Improve the diagnostics for shadows template parameter to report correct location (#GH129060).

Improvements to Clang's time-trace
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2 changes: 1 addition & 1 deletion clang/include/clang/Basic/DiagnosticSemaKinds.td
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Expand Up @@ -7157,7 +7157,7 @@ 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">,
"comparisons like 'X %0 Y %1 Z' don't have their mathematical meaning">,
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@AaronBallman AaronBallman Mar 5, 2025

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Suggested change
"comparisons like 'X %0 Y %1 Z' don't have their mathematical meaning">,
"chained comparison 'X %0 Y %1 Z' does not behave the same as a mathematical expression">,

InGroup<Parentheses>, DefaultError;

def warn_enum_constant_in_bool_context : Warning<
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3 changes: 2 additions & 1 deletion clang/lib/Sema/SemaExpr.cpp
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Expand Up @@ -14924,7 +14924,8 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,

if (const auto *BI = dyn_cast<BinaryOperator>(LHSExpr);
BI && BI->isComparisonOp())
Diag(OpLoc, diag::warn_consecutive_comparison);
Diag(OpLoc, diag::warn_consecutive_comparison)
<< BI->getOpcodeStr() << BinaryOperator::getOpcodeStr(Opc);

break;
case BO_EQ:
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4 changes: 2 additions & 2 deletions clang/test/Sema/bool-compare.c
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Expand Up @@ -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) {} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
if (a>y<z) {} // expected-error {{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
Expand Down Expand Up @@ -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) {} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
if (z<a>y) {} // expected-error {{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
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8 changes: 4 additions & 4 deletions clang/test/Sema/parentheses.cpp
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Expand Up @@ -217,10 +217,10 @@ namespace PR20735 {
}

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); // 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

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4 changes: 2 additions & 2 deletions clang/test/SemaCXX/bool-compare.cpp
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Expand Up @@ -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) {} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
if (a>y<z) {} // expected-error {{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
Expand Down Expand Up @@ -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) {} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
if (z<a>y) {} // expected-error {{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
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2 changes: 1 addition & 1 deletion clang/test/SemaCXX/cxx2a-adl-only-template-id.cpp
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Expand Up @@ -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}} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
f<0>(q); // expected-error {{invalid operands to binary expression}} // expected-error {{comparisons like 'X < Y > Z' don't have their mathematical meaning}}
}

void disambig() {
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2 changes: 1 addition & 1 deletion clang/test/SemaTemplate/typo-dependent-name.cpp
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Expand Up @@ -20,7 +20,7 @@ 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; // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
return this->inner < other > ::z; // expected-error {{comparisons like 'X < Y > Z' don't have their mathematical meaning}}
}
};

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2 changes: 1 addition & 1 deletion clang/test/SemaTemplate/typo-template-name.cpp
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Expand Up @@ -36,7 +36,7 @@ namespace InExpr {

// These are valid expressions.
foo<foo; // expected-warning {{self-comparison}}
foo<int()>(0); // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
foo<int()>(0); // expected-error {{comparisons like 'X < Y > Z' don't have their mathematical meaning}}
foo<int(), true>(false);
foo<Base{}.n;
}
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