Author: Amr Hesham Date: 2024-12-04T19:33:25+01:00 New Revision: 7347e5e89a671d675ba144e181e3d24bd072f527
URL: https://github.com/llvm/llvm-project/commit/7347e5e89a671d675ba144e181e3d24bd072f527 DIFF: https://github.com/llvm/llvm-project/commit/7347e5e89a671d675ba144e181e3d24bd072f527.diff LOG: [Clang] Add '-Warray-compare' flag for C++ below version 20 (#118031) Currently, we support `-wdeprecated-array-compare` for C++20 or above and don't report any warning for older versions, this PR supports `-Warray-compare` for older versions and for GCC compatibility. Fixes #114770 Added: clang/test/SemaCXX/warn-array-comparion.cpp Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Basic/DiagnosticSemaKinds.td clang/lib/Sema/SemaExpr.cpp clang/test/Analysis/reference.cpp clang/test/Sema/warn-stringcompare.c clang/test/SemaCXX/deprecated.cpp clang/test/SemaCXX/warn-self-comparisons.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 7f7d077e284af3..16c7f770f9b858 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -419,6 +419,9 @@ New Compiler Flags existing ``-fno-c++-static-destructors`` flag) skips all static destructors registration. +- The ``-Warray-compare`` warning has been added to warn about array comparison + on versions older than C++20. + Deprecated Compiler Flags ------------------------- diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 8020be6c57bcfb..2137cb713164ad 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -10269,6 +10269,11 @@ def warn_depr_array_comparison : Warning< "to compare array addresses, use unary '+' to decay operands to pointers">, InGroup<DeprecatedArrayCompare>; +def warn_array_comparison : Warning< + "comparison between two arrays compare their addresses and will be deprecated in c++20; " + "to compare array addresses, use unary '+' to decay operands to pointers">, + InGroup<DiagGroup<"array-compare">>; + 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 adad14cc0f1f6b..4ffce2c1236610 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -11833,14 +11833,21 @@ static void diagnoseTautologicalComparison(Sema &S, SourceLocation Loc, AlwaysEqual, // std::strong_ordering::equal from operator<=> }; + // C++1a [array.comp]: + // Equality and relational comparisons ([expr.eq], [expr.rel]) between two + // operands of array type. // C++2a [depr.array.comp]: // Equality and relational comparisons ([expr.eq], [expr.rel]) between two // operands of array type are deprecated. - if (S.getLangOpts().CPlusPlus20 && LHSStripped->getType()->isArrayType() && + if (S.getLangOpts().CPlusPlus && LHSStripped->getType()->isArrayType() && RHSStripped->getType()->isArrayType()) { - S.Diag(Loc, diag::warn_depr_array_comparison) - << LHS->getSourceRange() << RHS->getSourceRange() - << LHSStripped->getType() << RHSStripped->getType(); + auto IsDeprArrayComparionIgnored = + S.getDiagnostics().isIgnored(diag::warn_depr_array_comparison, Loc); + auto DiagID = !S.getLangOpts().CPlusPlus20 || IsDeprArrayComparionIgnored + ? diag::warn_array_comparison + : diag::warn_depr_array_comparison; + S.Diag(Loc, DiagID) << LHS->getSourceRange() << RHS->getSourceRange() + << LHSStripped->getType() << RHSStripped->getType(); // Carry on to produce the tautological comparison warning, if this // expression is potentially-evaluated, we can resolve the array to a // non-weak declaration, and so on. diff --git a/clang/test/Analysis/reference.cpp b/clang/test/Analysis/reference.cpp index b893aec2a7d542..91ba3cd23249a3 100644 --- a/clang/test/Analysis/reference.cpp +++ b/clang/test/Analysis/reference.cpp @@ -89,8 +89,8 @@ namespace PR13440 { S s = { a }; S2 s2 = { a }; - if (s.x != a) return; - if (s2.x != a) return; + if (s.x != a) return; // expected-warning {{comparison between two arrays}} + if (s2.x != a) return; // expected-warning {{comparison between two arrays}} a[0] = 42; clang_analyzer_eval(s.x[0] == 42); // expected-warning{{TRUE}} diff --git a/clang/test/Sema/warn-stringcompare.c b/clang/test/Sema/warn-stringcompare.c index 77876ad6abd6e7..78145cf42578a4 100644 --- a/clang/test/Sema/warn-stringcompare.c +++ b/clang/test/Sema/warn-stringcompare.c @@ -1,5 +1,5 @@ // RUN: %clang_cc1 -x c -fsyntax-only -verify %s -// RUN: %clang_cc1 -x c++ -fsyntax-only -verify %s +// RUN: %clang_cc1 -x c++ -fsyntax-only -verify=expected,cxx %s #define DELIM "/" #define DOT "." @@ -15,15 +15,15 @@ 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; + return; // cxx-warning@-1 {{comparison between two arrays}} if (DELIM == "/") // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}} - return; + return; // cxx-warning@-1 {{comparison between two arrays}} 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; + return; // cxx-warning@-1 {{comparison between two arrays}} if (DELIM == DOT) // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}} - return; + return; // cxx-warning@-1 {{comparison between two arrays}} } diff --git a/clang/test/SemaCXX/deprecated.cpp b/clang/test/SemaCXX/deprecated.cpp index 667f4d7d3edb03..4282239af81b4c 100644 --- a/clang/test/SemaCXX/deprecated.cpp +++ b/clang/test/SemaCXX/deprecated.cpp @@ -246,17 +246,19 @@ namespace ArithConv { namespace ArrayComp { int arr1[3], arr2[4]; - bool b1 = arr1 == arr2; // expected-warning {{array comparison always evaluates to false}} cxx20-warning {{comparison between two arrays is deprecated}} - bool b2 = arr1 < arr2; // expected-warning {{array comparison always evaluates to a constant}} cxx20-warning {{comparison between two arrays is deprecated}} + bool b1 = arr1 == arr2; // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} + // expected-warning@-1 {{array comparison always evaluates to false}} + bool b2 = arr1 < arr2; // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} + // expected-warning@-1 {{array comparison always evaluates to a constant}} __attribute__((weak)) int arr3[3]; - bool b3 = arr1 == arr3; // cxx20-warning {{comparison between two arrays is deprecated}} - bool b4 = arr1 < arr3; // cxx20-warning {{comparison between two arrays is deprecated}} + bool b3 = arr1 == arr3; // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} + bool b4 = arr1 < arr3; // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} #if __cplusplus > 201703L bool b5 = arr1 <=> arr2; // cxx20-error {{invalid operands}} #endif int (&f())[3]; - bool b6 = arr1 == f(); // cxx20-warning {{comparison between two arrays is deprecated}} + bool b6 = arr1 == f(); // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} bool b7 = arr1 == +f(); } diff --git a/clang/test/SemaCXX/warn-array-comparion.cpp b/clang/test/SemaCXX/warn-array-comparion.cpp new file mode 100644 index 00000000000000..a6eaaab22fc16d --- /dev/null +++ b/clang/test/SemaCXX/warn-array-comparion.cpp @@ -0,0 +1,21 @@ +// 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 + +typedef struct { + char str[16]; + int id[16]; +} Object; + +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; + 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 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}} +} diff --git a/clang/test/SemaCXX/warn-self-comparisons.cpp b/clang/test/SemaCXX/warn-self-comparisons.cpp index 2e8d130bcd5a0a..3847c2d918bf61 100644 --- a/clang/test/SemaCXX/warn-self-comparisons.cpp +++ b/clang/test/SemaCXX/warn-self-comparisons.cpp @@ -1,6 +1,6 @@ -// RUN: %clang_cc1 -fsyntax-only -verify %s -// expected-no-diagnostics +// 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 void f(int (&array1)[2], int (&array2)[2]) { - if (array1 == array2) { } // no warning + if (array1 == array2) { } // not-cxx20-warning {{comparison between two arrays compare their addresses}} cxx20-warning {{comparison between two arrays is deprecated}} } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
