b062ee7dc4
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
34 lines
1.5 KiB
C++
34 lines
1.5 KiB
C++
// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection \
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// RUN: -analyzer-config eagerly-assume=false -std=c++20 -verify %s
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template <class T> void clang_analyzer_dump(T);
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void clang_analyzer_eval(bool);
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struct Box {
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int value;
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};
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bool operator ==(Box lhs, Box rhs) {
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return lhs.value == rhs.value;
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}
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template <Box V> void dumps() {
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clang_analyzer_dump(V); // expected-warning {{lazyCompoundVal}}
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clang_analyzer_dump(&V); // expected-warning {{Unknown}}
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clang_analyzer_dump(V.value); // expected-warning {{Unknown}} FIXME: It should be '6 S32b'.
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clang_analyzer_dump(&V.value); // expected-warning {{Unknown}}
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}
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template void dumps<Box{6}>();
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// [temp.param].7.3.2:
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// "All such template parameters in the program of the same type with the
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// same value denote the same template parameter object."
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template <Box A1, Box A2, Box B1, Box B2> void stable_addresses() {
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clang_analyzer_eval(&A1 == &A2); // expected-warning {{UNKNOWN}} FIXME: It should be TRUE.
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clang_analyzer_eval(&B1 == &B2); // expected-warning {{UNKNOWN}} FIXME: It should be TRUE.
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clang_analyzer_eval(&A1 == &B2); // expected-warning {{UNKNOWN}} FIXME: It should be FALSE.
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clang_analyzer_eval(A1 == A2); // expected-warning {{UNKNOWN}} FIXME: It should be TRUE.
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clang_analyzer_eval(B1 == B2); // expected-warning {{UNKNOWN}} FIXME: It should be TRUE.
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clang_analyzer_eval(A1 == B2); // expected-warning {{UNKNOWN}} FIXME: It should be FALSE.
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}
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template void stable_addresses<Box{1}, Box{1}, Box{2}, Box{2}>();
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