[cfe-dev] Same AST for is_same<char, int>::value and is_same<char, long>::value

[Benics Balázs via cfe-dev]

(Resending from my personal email address)


________________________________
From: Balázs Benics <balazs.benics at sigmatechnology.se>
Sent: Tuesday, November 23, 2021, 14:45
To: cfe-dev
Subject: Same AST for is_same::value and is_same::value

I seek some advice on the following AST scenario.
https://godbolt.org/z/WcTeoGcbG

1  #include <type_traits>
2  using std::is_same;
3  bool top() {
4    return is_same<char, int>::value || is_same<char, long>::value;
5  }

The `alpha.core.IdenticalExpr` static analyzer checker warns about that the two `..::value` are identical DeclRefExprs.
According to the AST, they are indeed identical:

  BinaryOperator <col:10, col:60> 'bool' '||'
  |-ImplicitCastExpr <col:10, col:30> 'bool':'bool' <LValueToRValue>
  | `-DeclRefExpr <col:10, col:30> 'const bool':'const bool' lvalue Var 0x563b67cde0a8 'value' 'const bool':'const bool'
  `-ImplicitCastExpr <col:39, col:60> 'bool':'bool' <LValueToRValue>
    `-DeclRefExpr <col:39, col:60> 'const bool':'const bool' lvalue Var 0x563b67cde0a8 'value' 'const bool':'const bool'

Both of them refers to the same `VarDecl`, corresponding (probably) to the `std::false_type::value`.

How can I detect that even though the `values` look similar, they correspond to different template instances in that sense?
What do you suggest?
In the end, I want to suppress these reports in the static analyzer.

Balázs

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