Author: Balazs Benics Date: 2022-11-15T15:37:36-08:00 New Revision: 11c3a21f8d1ba21c7744ba9d272c26c2ce3c58a0
URL: https://github.com/llvm/llvm-project/commit/11c3a21f8d1ba21c7744ba9d272c26c2ce3c58a0 DIFF: https://github.com/llvm/llvm-project/commit/11c3a21f8d1ba21c7744ba9d272c26c2ce3c58a0.diff LOG: [analyzer] Workaround crash on encountering Class non-type template parameters The Clang Static Analyzer will crash on this code: ```lang=C++ struct Box { int value; }; template <Box V> int get() { return V.value; } template int get<Box{-1}>(); ``` https://godbolt.org/z/5Yb1sMMMb The problem is that we don't account for encountering `TemplateParamObjectDecl`s within the `DeclRefExpr` handler in the `ExprEngine`. IMO we should create a new memregion for representing such template param objects, to model their language semantics. Such as: - it should have global static storage - for two identical values, their addresses should be identical as well http://eel.is/c%2B%2Bdraft/temp.param#8 I was thinking of introducing a `TemplateParamObjectRegion` under `DeclRegion` for this purpose. It could have `TemplateParamObjectDecl` as a field. The `TemplateParamObjectDecl::getValue()` returns `APValue`, which might represent multiple levels of structures, unions and other goodies - making the transformation from `APValue` to `SVal` a bit complicated. That being said, for now, I think having `Unknowns` for such cases is definitely an improvement to crashing, hence I'm proposing this patch. Reviewed By: xazax.hun Differential Revision: https://reviews.llvm.org/D135763 (cherry picked from commit b062ee7dc4515b0a42157717105839627d5542bb) Added: clang/test/Analysis/template-param-objects.cpp Modified: clang/lib/StaticAnalyzer/Core/ExprEngine.cpp Removed: ################################################################################ diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp index 19149d0798229..ab65612bce90e 100644 --- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp +++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp @@ -2839,6 +2839,12 @@ void ExprEngine::VisitCommonDeclRefExpr(const Expr *Ex, const NamedDecl *D, return; } + if (const auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) { + // FIXME: We should meaningfully implement this. + (void)TPO; + return; + } + llvm_unreachable("Support for this Decl not implemented."); } diff --git a/clang/test/Analysis/template-param-objects.cpp b/clang/test/Analysis/template-param-objects.cpp new file mode 100644 index 0000000000000..dde95fa62cb65 --- /dev/null +++ b/clang/test/Analysis/template-param-objects.cpp @@ -0,0 +1,33 @@ +// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection \ +// RUN: -analyzer-config eagerly-assume=false -std=c++20 -verify %s + +template <class T> void clang_analyzer_dump(T); +void clang_analyzer_eval(bool); + +struct Box { + int value; +}; +bool operator ==(Box lhs, Box rhs) { + return lhs.value == rhs.value; +} +template <Box V> void dumps() { + clang_analyzer_dump(V); // expected-warning {{lazyCompoundVal}} + clang_analyzer_dump(&V); // expected-warning {{Unknown}} + clang_analyzer_dump(V.value); // expected-warning {{Unknown}} FIXME: It should be '6 S32b'. + clang_analyzer_dump(&V.value); // expected-warning {{Unknown}} +} +template void dumps<Box{6}>(); + +// [temp.param].7.3.2: +// "All such template parameters in the program of the same type with the +// same value denote the same template parameter object." +template <Box A1, Box A2, Box B1, Box B2> void stable_addresses() { + clang_analyzer_eval(&A1 == &A2); // expected-warning {{UNKNOWN}} FIXME: It should be TRUE. + clang_analyzer_eval(&B1 == &B2); // expected-warning {{UNKNOWN}} FIXME: It should be TRUE. + clang_analyzer_eval(&A1 == &B2); // expected-warning {{UNKNOWN}} FIXME: It should be FALSE. + + clang_analyzer_eval(A1 == A2); // expected-warning {{UNKNOWN}} FIXME: It should be TRUE. + clang_analyzer_eval(B1 == B2); // expected-warning {{UNKNOWN}} FIXME: It should be TRUE. + clang_analyzer_eval(A1 == B2); // expected-warning {{UNKNOWN}} FIXME: It should be FALSE. +} +template void stable_addresses<Box{1}, Box{1}, Box{2}, Box{2}>(); _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits