[clang] [clang] Catch missing format attributes (PR #105479)
Budimir Aranđelović via cfe-commits
cfe-commits at lists.llvm.org
Fri Oct 11 07:12:09 PDT 2024
================
@@ -5335,6 +5335,217 @@ static void handlePreferredTypeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
D->addAttr(::new (S.Context) PreferredTypeAttr(S.Context, AL, ParmTSI));
}
+// This function is called only if function call is not inside template body.
+// TODO: Add call for function calls inside template body.
+// Emit warnings if parent function misses format attributes.
+void Sema::DiagnoseMissingFormatAttributes(Stmt *Body,
+ const FunctionDecl *FDecl) {
+ assert(FDecl);
+
+ // If there are no function body, exit.
+ if (!Body)
+ return;
+
+ // Get missing format attributes
+ std::vector<FormatAttr *> MissingFormatAttributes =
+ GetMissingFormatAttributes(Body, FDecl);
+ if (MissingFormatAttributes.empty())
+ return;
+
+ // Check if there are more than one format type found. In that case do not
+ // emit diagnostic.
+ const clang::IdentifierInfo *AttrType = MissingFormatAttributes[0]->getType();
+ if (llvm::any_of(MissingFormatAttributes, [&](const FormatAttr *Attr) {
+ return AttrType != Attr->getType();
+ }))
+ return;
+
+ for (const FormatAttr *FA : MissingFormatAttributes) {
+ // If format index and first-to-check argument index are negative, it means
+ // that this attribute is only saved for multiple format types checking.
+ if (FA->getFormatIdx() < 0 || FA->getFirstArg() < 0)
+ continue;
+
+ // Emit diagnostic
+ SourceLocation Loc = FDecl->getLocation();
+ Diag(Loc, diag::warn_missing_format_attribute)
+ << FA->getType() << FDecl
+ << FixItHint::CreateInsertion(Loc,
+ (llvm::Twine("__attribute__((format(") +
+ FA->getType()->getName() + ", " +
+ llvm::Twine(FA->getFormatIdx()) + ", " +
+ llvm::Twine(FA->getFirstArg()) + ")))")
+ .str());
+ }
+}
+
+// Returns vector of format attributes. There are no two attributes with same
+// arguments in returning vector. There can be attributes that effectivelly only
+// store information about format type.
+std::vector<FormatAttr *>
+Sema::GetMissingFormatAttributes(Stmt *Body, const FunctionDecl *FDecl) {
+ unsigned int FunctionFormatArgumentIndexOffset =
+ checkIfMethodHasImplicitObjectParameter(FDecl) ? 2 : 1;
+
+ std::vector<FormatAttr *> MissingAttributes;
+
+ // Iterate over body statements.
+ for (auto *Child : Body->children()) {
+ // If child statement is compound statement, recursively get missing
+ // attributes.
+ if (dyn_cast_or_null<CompoundStmt>(Child)) {
+ std::vector<FormatAttr *> CompoundStmtMissingAttributes =
+ GetMissingFormatAttributes(Child, FDecl);
+
+ // If there are already missing attributes with same arguments, do not add
+ // duplicates.
+ for (FormatAttr *FA : CompoundStmtMissingAttributes) {
+ if (!llvm::any_of(MissingAttributes, [&](const FormatAttr *Attr) {
+ return FA->getType() == Attr->getType() &&
+ FA->getFormatIdx() == Attr->getFormatIdx() &&
+ FA->getFirstArg() == Attr->getFirstArg();
+ }))
+ MissingAttributes.push_back(FA);
+ }
+
+ continue;
+ }
+
+ ValueStmt *VS = dyn_cast_or_null<ValueStmt>(Child);
+ if (!VS)
+ continue;
+ Expr *TheExpr = VS->getExprStmt();
+ if (!TheExpr)
+ continue;
+ CallExpr *TheCall = dyn_cast_or_null<CallExpr>(TheExpr);
+ if (!TheCall)
+ continue;
+ const FunctionDecl *ChildFunction =
+ dyn_cast_or_null<FunctionDecl>(TheCall->getCalleeDecl());
+ if (!ChildFunction || !ChildFunction->hasAttr<FormatAttr>())
+ continue;
+
+ Expr **Args = TheCall->getArgs();
+ unsigned int NumArgs = TheCall->getNumArgs();
+
+ // If child expression is function, check if it is format function.
+ // If it is, check if parent function misses format attributes.
+
+ unsigned int ChildFunctionFormatArgumentIndexOffset =
+ checkIfMethodHasImplicitObjectParameter(ChildFunction) ? 2 : 1;
+
+ // If child function is format function and format arguments are not
+ // relevant to emit diagnostic, save only information about format type
+ // (format index and first-to-check argument index are set to -1).
+ // Information about format type is later used to determine if there are
+ // more than one format type found.
+
+ // Check if function has format attribute with forwarded format string.
+ IdentifierInfo *AttrType;
+ const ParmVarDecl *FormatArg;
+ if (!llvm::any_of(ChildFunction->specific_attrs<FormatAttr>(),
+ [&](const FormatAttr *Attr) {
+ AttrType = Attr->getType();
+
+ int OffsetFormatIndex =
+ Attr->getFormatIdx() -
+ ChildFunctionFormatArgumentIndexOffset;
+ if (OffsetFormatIndex < 0 ||
+ (unsigned)OffsetFormatIndex >= NumArgs)
+ return false;
+
+ const auto *FormatArgExpr = dyn_cast<DeclRefExpr>(
+ Args[OffsetFormatIndex]->IgnoreParenCasts());
+ if (!FormatArgExpr)
+ return false;
+
+ FormatArg = dyn_cast_or_null<ParmVarDecl>(
+ FormatArgExpr->getReferencedDeclOfCallee());
+ if (!FormatArg)
+ return false;
+
+ return true;
+ })) {
+ MissingAttributes.push_back(
+ FormatAttr::CreateImplicit(getASTContext(), AttrType, -1, -1));
+ continue;
+ }
+
+ // Do not add in a vector format attributes whose type is different than
+ // parent function attribute type.
+ if (llvm::any_of(FDecl->specific_attrs<FormatAttr>(),
+ [&](const FormatAttr *FunctionAttr) {
+ return AttrType != FunctionAttr->getType();
+ }))
+ continue;
+
+ // Check if format string argument is parent function parameter.
+ int StringIndex = 0;
+ if (!llvm::any_of(FDecl->parameters(), [&](const ParmVarDecl *Param) {
+ if (Param != FormatArg)
+ return false;
+
+ StringIndex = Param->getFunctionScopeIndex() +
+ FunctionFormatArgumentIndexOffset;
+
+ return true;
+ })) {
+ MissingAttributes.push_back(
+ FormatAttr::CreateImplicit(getASTContext(), AttrType, -1, -1));
+ continue;
+ }
+
+ unsigned NumOfParentFunctionParams = FDecl->getNumParams();
+
+ // Compare parent and calling function format attribute arguments (archetype
+ // and format string).
+ if (llvm::any_of(
+ FDecl->specific_attrs<FormatAttr>(), [&](const FormatAttr *Attr) {
+ if (Attr->getType() != AttrType)
+ return false;
+ int OffsetFormatIndex =
+ Attr->getFormatIdx() - FunctionFormatArgumentIndexOffset;
+
+ if (OffsetFormatIndex < 0 ||
+ (unsigned)OffsetFormatIndex >= NumOfParentFunctionParams)
+ return false;
+
+ if (FDecl->parameters()[OffsetFormatIndex] != FormatArg)
+ return false;
+
+ return true;
+ })) {
+ MissingAttributes.push_back(
+ FormatAttr::CreateImplicit(getASTContext(), AttrType, -1, -1));
+ continue;
+ }
+
+ // Get first argument index
+ int FirstToCheck = [&]() -> unsigned {
+ if (!FDecl->isVariadic())
+ return 0;
+ const auto *FirstToCheckArg = Args[NumArgs - 1]->IgnoreParenCasts();
+ if (FirstToCheckArg->getType().getCanonicalType() !=
+ Context.getBuiltinVaListType().getCanonicalType())
+ return 0;
+ return NumOfParentFunctionParams + FunctionFormatArgumentIndexOffset;
+ }();
+
+ // If there are already attributes which arguments matches arguments
+ // detected in this iteration, do not add new attribute as it would be
+ // duplicate.
+ if (!llvm::any_of(MissingAttributes, [&](const FormatAttr *Attr) {
+ return Attr->getType() == AttrType &&
+ Attr->getFormatIdx() == StringIndex &&
+ Attr->getFirstArg() == FirstToCheck;
+ }))
----------------
budimirarandjelovichtec wrote:
It is true that duplicates are also eliminated earlier, but keep in mind that this iteration forks and can go in one of three opportunities:
1) If child statement is compound statement, format attributes are got recursively for child statement and it this branch is one elimination of duplicates. Then, loop continues to next iteration.
2) If child statement is function call, there is check if format attribute is missing. If it is case, before adding to the vector, there is check for duplicates. After all, loop continues to next iteration.
3) If none of previous conditions are satisfied, loop continues to next iteration.
So, parts of code that eliminate duplicates are in different branches and both snippets cannot be executed in one iteration.
https://github.com/llvm/llvm-project/pull/105479
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