From 3f458cd9abbf99cddcded076b5e7b4049607b7b4 Mon Sep 17 00:00:00 2001 From: Amr Hesham Date: Sat, 7 Dec 2024 18:28:09 +0100 Subject: [PATCH] [Clang] Warning as error Array Comparisons from C++26 (#118872) Starting from C++26 the array comparison warning should converted to an error. Fixes: #117859 --- .../clang-tidy/checkers/misc/redundant-expression.cpp | 2 +- clang/docs/ReleaseNotes.rst | 3 +++ clang/include/clang/Basic/DiagnosticSemaKinds.td | 5 +++++ clang/lib/Sema/SemaExpr.cpp | 4 +++- clang/test/Sema/warn-stringcompare.c | 9 +++++---- clang/test/SemaCXX/warn-array-comparion.cpp | 6 ++++-- clang/test/SemaCXX/warn-self-comparisons.cpp | 2 ++ clang/www/cxx_status.html | 2 +- 8 files changed, 24 insertions(+), 9 deletions(-) diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/redundant-expression.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/redundant-expression.cpp index 1b271630e0d1..7396d2dce76c 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/misc/redundant-expression.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/misc/redundant-expression.cpp @@ -1,4 +1,4 @@ -// RUN: %check_clang_tidy %s misc-redundant-expression %t -- -- -fno-delayed-template-parsing +// RUN: %check_clang_tidy %s misc-redundant-expression %t -- -- -fno-delayed-template-parsing -Wno-array-compare-cxx26 typedef __INT64_TYPE__ I64; diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 59e3a6609123..12d8ebf3251b 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -428,6 +428,9 @@ New Compiler Flags - The ``-Warray-compare`` warning has been added to warn about array comparison on versions older than C++20. +- The ``-Warray-compare-cxx26`` warning has been added to warn about array comparison + starting from C++26, this warning is enabled as an error by default. + Deprecated Compiler Flags ------------------------- diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 61dd0c53581a..f185a98720f5 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -10274,6 +10274,11 @@ def warn_array_comparison : Warning< "to compare array addresses, use unary '+' to decay operands to pointers">, InGroup>; +def warn_array_comparison_cxx26 : Warning< + "comparison between two arrays is ill-formed in C++26; " + "to compare array addresses, use unary '+' to decay operands to pointers">, + InGroup>, DefaultError; + def warn_stringcompare : Warning< "result of comparison against %select{a string literal|@encode}0 is " "unspecified (use an explicit string comparison function instead)">, diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 4ffce2c12366..14564b99de44 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -11843,7 +11843,9 @@ static void diagnoseTautologicalComparison(Sema &S, SourceLocation Loc, RHSStripped->getType()->isArrayType()) { auto IsDeprArrayComparionIgnored = S.getDiagnostics().isIgnored(diag::warn_depr_array_comparison, Loc); - auto DiagID = !S.getLangOpts().CPlusPlus20 || IsDeprArrayComparionIgnored + auto DiagID = S.getLangOpts().CPlusPlus26 + ? diag::warn_array_comparison_cxx26 + : !S.getLangOpts().CPlusPlus20 || IsDeprArrayComparionIgnored ? diag::warn_array_comparison : diag::warn_depr_array_comparison; S.Diag(Loc, DiagID) << LHS->getSourceRange() << RHS->getSourceRange() diff --git a/clang/test/Sema/warn-stringcompare.c b/clang/test/Sema/warn-stringcompare.c index 78145cf42578..44dc0a5de3a4 100644 --- a/clang/test/Sema/warn-stringcompare.c +++ b/clang/test/Sema/warn-stringcompare.c @@ -1,5 +1,6 @@ // RUN: %clang_cc1 -x c -fsyntax-only -verify %s // RUN: %clang_cc1 -x c++ -fsyntax-only -verify=expected,cxx %s +// RUN: %clang_cc1 -x c++ -std=c++26 -fsyntax-only -verify=expected,cxx26 %s #define DELIM "/" #define DOT "." @@ -15,15 +16,15 @@ void test(const char *d) { if (NULL == "/") return; if ("/" != DELIM) // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}} - return; // cxx-warning@-1 {{comparison between two arrays}} + return; // cxx-warning@-1 {{comparison between two arrays}} cxx26-error@-1 {{comparison between two arrays is ill-formed in C++26}} if (DELIM == "/") // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}} - return; // cxx-warning@-1 {{comparison between two arrays}} + return; // cxx-warning@-1 {{comparison between two arrays}} cxx26-error@-1 {{comparison between two arrays is ill-formed in C++26}} if (DELIM != NULL) return; if (NULL == DELIM) return; if (DOT != DELIM) // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}} - return; // cxx-warning@-1 {{comparison between two arrays}} + return; // cxx-warning@-1 {{comparison between two arrays}} cxx26-error@-1 {{comparison between two arrays is ill-formed in C++26}} if (DELIM == DOT) // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}} - return; // cxx-warning@-1 {{comparison between two arrays}} + return; // cxx-warning@-1 {{comparison between two arrays}} cxx26-error@-1 {{comparison between two arrays is ill-formed in C++26}} } diff --git a/clang/test/SemaCXX/warn-array-comparion.cpp b/clang/test/SemaCXX/warn-array-comparion.cpp index a6eaaab22fc1..2bd4218f3a27 100644 --- a/clang/test/SemaCXX/warn-array-comparion.cpp +++ b/clang/test/SemaCXX/warn-array-comparion.cpp @@ -1,6 +1,7 @@ // RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify %s -verify=expected,not-cxx20 // RUN: %clang_cc1 -std=c++20 -fsyntax-only -Wno-deprecated-array-compare -verify %s -verify=expected,not-cxx20 // RUN: %clang_cc1 -std=c++20 -fsyntax-only -Wdeprecated -verify %s -verify=expected,cxx20 +// RUN: %clang_cc1 -std=c++26 -fsyntax-only -Wdeprecated -verify %s -verify=expected,cxx26 typedef struct { char str[16]; @@ -9,13 +10,14 @@ typedef struct { bool object_equal(const Object &obj1, const Object &obj2) { if (obj1.str != obj2.str) // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} - return false; + return false; // cxx26-error@-1 {{comparison between two arrays is ill-formed in C++26}} if (obj1.id != obj2.id) // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} - return false; + return false; // cxx26-error@-1 {{comparison between two arrays is ill-formed in C++26}} return true; } void foo(int (&array1)[2], int (&array2)[2]) { if (array1 == array2) { } // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} + // cxx26-error@-1 {{comparison between two arrays is ill-formed in C++26}} } diff --git a/clang/test/SemaCXX/warn-self-comparisons.cpp b/clang/test/SemaCXX/warn-self-comparisons.cpp index 3847c2d918bf..1ea8b971fcd5 100644 --- a/clang/test/SemaCXX/warn-self-comparisons.cpp +++ b/clang/test/SemaCXX/warn-self-comparisons.cpp @@ -1,6 +1,8 @@ // RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify %s -verify=expected,not-cxx20 // RUN: %clang_cc1 -std=c++20 -fsyntax-only -Wdeprecated -verify %s -verify=expected,cxx20 +// RUN: %clang_cc1 -std=c++26 -fsyntax-only -Wdeprecated -verify %s -verify=expected,cxx26 void f(int (&array1)[2], int (&array2)[2]) { if (array1 == array2) { } // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} + // cxx26-error@-1 {{comparison between two arrays is ill-formed in C++26}} } diff --git a/clang/www/cxx_status.html b/clang/www/cxx_status.html index fdb9807b1168..a8e79cd3475a 100755 --- a/clang/www/cxx_status.html +++ b/clang/www/cxx_status.html @@ -239,7 +239,7 @@ C++23, informally referred to as C++26.

Remove Deprecated Array Comparisons from C++26 P2865R6 - No + Clang 20 Structured Bindings can introduce a Pack