https://github.com/budimirarandjelovicsyrmia created https://github.com/llvm/llvm-project/pull/70024
Enable flag -Wmissing-format-attribute to catch missing attributes From 9d0b6ae67776a9adf9ca3eee64b2e01de9f07af4 Mon Sep 17 00:00:00 2001 From: budimirarandjelovicsyrmia <budimir.arandjelo...@syrmia.com> Date: Fri, 13 Oct 2023 14:45:15 +0200 Subject: [PATCH] [clang] Catch missing format attributes --- clang/include/clang/Basic/DiagnosticGroups.td | 2 +- .../clang/Basic/DiagnosticSemaKinds.td | 3 + clang/include/clang/Sema/Sema.h | 2 + clang/lib/Sema/SemaAttr.cpp | 80 +++++++++++++++++++ clang/lib/Sema/SemaChecking.cpp | 4 +- clang/test/Sema/attr-format-missing.c | 13 +++ 6 files changed, 102 insertions(+), 2 deletions(-) create mode 100644 clang/test/Sema/attr-format-missing.c diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td index 17fdcffa2d42740..b8b77df84beb2be 100644 --- a/clang/include/clang/Basic/DiagnosticGroups.td +++ b/clang/include/clang/Basic/DiagnosticGroups.td @@ -482,7 +482,7 @@ def MainReturnType : DiagGroup<"main-return-type">; def MaxUnsignedZero : DiagGroup<"max-unsigned-zero">; def MissingBraces : DiagGroup<"missing-braces">; def MissingDeclarations: DiagGroup<"missing-declarations">; -def : DiagGroup<"missing-format-attribute">; +def MissingFormatAttribute: DiagGroup<"missing-format-attribute">; def : DiagGroup<"missing-include-dirs">; def MissingNoreturn : DiagGroup<"missing-noreturn">; def MultiChar : DiagGroup<"multichar">; diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 6d6f474f6dcdab9..7125de143c1710e 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -936,6 +936,9 @@ def err_opencl_invalid_param : Error< def err_opencl_invalid_return : Error< "declaring function return value of type %0 is not allowed %select{; did you forget * ?|}1">; def warn_enum_value_overflow : Warning<"overflow in enumeration value">; +def warn_missing_format_attribute : Warning< + "Function %0 might be candidate for %1 format attribute.">, + InGroup<MissingFormatAttribute>, DefaultIgnore; def warn_pragma_options_align_reset_failed : Warning< "#pragma options align=reset failed: %0">, InGroup<IgnoredPragmas>; diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index 741c2503127af7a..7041a309e5df220 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -10615,6 +10615,8 @@ class Sema final { ChangedStateAtExit }; + void DiagnoseMissingFormatAttributes(NamedDecl *FDecl, SourceLocation Loc); + void DiagnoseNonDefaultPragmaAlignPack(PragmaAlignPackDiagnoseKind Kind, SourceLocation IncludeLoc); void DiagnoseUnterminatedPragmaAlignPack(); diff --git a/clang/lib/Sema/SemaAttr.cpp b/clang/lib/Sema/SemaAttr.cpp index 42f582724564d06..0a61748f6e20176 100644 --- a/clang/lib/Sema/SemaAttr.cpp +++ b/clang/lib/Sema/SemaAttr.cpp @@ -435,6 +435,86 @@ bool Sema::ConstantFoldAttrArgs(const AttributeCommonInfo &CI, return true; } +// Warn if parent function does not have builtin function format attribute. +void Sema::DiagnoseMissingFormatAttributes(NamedDecl *FDecl, + SourceLocation Loc) { + if (!FDecl) + return; + + auto *FD = dyn_cast_or_null<FunctionDecl>(FDecl); + if (!FD) + return; + + unsigned BuiltinID = FD->getBuiltinID(/*ConsiderWrappers=*/true); + + // Function is not builtin if it's builtin ID is 0. + if (!BuiltinID) + return; + + // Check if function is one with format attribute. + switch (BuiltinID) { + case Builtin::BIprintf: + case Builtin::BIfprintf: + case Builtin::BIsprintf: + case Builtin::BIscanf: + case Builtin::BIfscanf: + case Builtin::BIsscanf: + case Builtin::BIvprintf: + case Builtin::BIvfprintf: + case Builtin::BIvsprintf: + break; + default: { + // In C99 mode check functions below. + if (!getLangOpts().C99) + return; + switch (BuiltinID) { + case Builtin::BIsnprintf: + case Builtin::BIvsnprintf: + case Builtin::BIvscanf: + case Builtin::BIvfscanf: + case Builtin::BIvsscanf: + break; + default: + return; + } + } + } + + Scope *ParentScope = getCurScope() ? getCurScope()->getFnParent() : nullptr; + if (!ParentScope) + return; + + DeclContext *ParentScopeEntity = ParentScope->getEntity(); + if (!ParentScopeEntity) + return; + if (ParentScopeEntity->getDeclKind() != Decl::Kind::Function) + return; + + FunctionDecl *ParentFuncDecl = static_cast<FunctionDecl *>(ParentScopeEntity); + if (!ParentFuncDecl) + return; + if (!ParentFuncDecl->isVariadic()) + return; + + // Iterate through builtin function format attributes. Then check + // if parent function has these attributes. If parent function does + // not have builtin function format attribut, emit warning. + for (const FormatAttr *Attr : FD->specific_attrs<FormatAttr>()) { + bool hasFormatAttr = false; + for (const FormatAttr *ParentAttr : + ParentFuncDecl->specific_attrs<FormatAttr>()) { + if (ParentAttr->getType() == Attr->getType()) { + hasFormatAttr = true; + break; + } + } + if (!hasFormatAttr) { + Diag(Loc, diag::warn_missing_format_attribute) + << ParentFuncDecl << Attr->getType(); + } + } +} + void Sema::DiagnoseNonDefaultPragmaAlignPack(PragmaAlignPackDiagnoseKind Kind, SourceLocation IncludeLoc) { if (Kind == PragmaAlignPackDiagnoseKind::NonDefaultStateAtInclude) { diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index 4602284309491c1..f2dd455c667a43b 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -6014,8 +6014,10 @@ void Sema::checkCall(NamedDecl *FDecl, const FunctionProtoType *Proto, } } - if (FD) + if (FD) { diagnoseArgDependentDiagnoseIfAttrs(FD, ThisArg, Args, Loc); + DiagnoseMissingFormatAttributes(FDecl, Range.getBegin()); + } } /// CheckConstructorCall - Check a constructor call for correctness and safety diff --git a/clang/test/Sema/attr-format-missing.c b/clang/test/Sema/attr-format-missing.c new file mode 100644 index 000000000000000..131d5d50d31d10b --- /dev/null +++ b/clang/test/Sema/attr-format-missing.c @@ -0,0 +1,13 @@ +// RUN: %clang_cc1 -fsyntax-only -verify -Wmissing-format-attribute %s +// RUN: %clang_cc1 -fsyntax-only -verify -std=c99 -Wmissing-format-attribute %s + +#include <stdarg.h> +#include <stdio.h> + +va_list args; + +__attribute__((__format__ (__scanf__, 1, 4))) +void foo(char *out, const size_t len, const char *format, ... /* args */) +{ + vsnprintf(out, len, format, args); // expected-warning {{Function 'foo' might be candidate for 'printf' format attribute}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits