[clang-tidy] Crash with modernize-use-integer-sign-comparison

[VReichelt]

Running clang-tidy with -checks='-*,modernize-use-integer-sign-comparison' and '-std=c++20' (or above) on the code

struct A
{
  unsigned size() const;
};

struct B
{
  A a;

  bool foo(const A& a2) const { return (int)a2.size() == size();  }
  int size() const { return (int)a.size(); }
};

triggers an assertion: clang-tidy: /tmp/LLVM/llvm-project/clang-tools-extra/clang-tidy/modernize/UseIntegerSignComparisonCheck.cpp:123: virtual void clang::tidy::modernize::UseIntegerSignComparisonCheck::check(const clang::ast_matchers::MatchFinder::MatchResult&): Assertion 'SignedCastExpression' failed.

This was introduced in the last two weeks, so I suspect this is due to the fix for #127471 .

@RiverDave , @vbvictor : Could you please have a look?

Stacktrace.txt

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: None (VReichelt)

Running clang-tidy with -checks='-*,modernize-use-integer-sign-comparison' and '-std=c++20' (or above) on the code

struct A
{
  unsigned size() const;
};

struct B
{
  A a;

  bool foo(const A& a2) const { return (int)a2.size() == size();  }
  int size() const { return (int)a.size(); }
};

triggers an assertion: clang-tidy: /tmp/LLVM/llvm-project/clang-tools-extra/clang-tidy/modernize/UseIntegerSignComparisonCheck.cpp:123: virtual void clang::tidy::modernize::UseIntegerSignComparisonCheck::check(const clang::ast_matchers::MatchFinder::MatchResult&): Assertion 'SignedCastExpression' failed.

This was introduced in the last two weeks, so I suspect this is due to the fix for #127471 .

@RiverDave , @vbvictor : Could you please have a look?

Stacktrace.txt

[EugeneZelenko]

See https://godbolt.org/z/GhYMc6Wbs

[RiverDave]

Taking a look at this as soon as I have the time

[vbvictor]

Thank you for the quick catch of the bug.
I think we need to revert the changes.

[vbvictor]

@RiverDave , you could create a revert pr if you wish (I see you got member!), or I can do it in 2-3 hours

[RiverDave]

@RiverDave , you could create a revert pr if you wish (I see you got member!), or I can do it in 2-3 hours

Done. as a side note what is the general procedure when catching these bugs? I mean once the revert is done, under which issue should everything be resolved?

[vbvictor]

under which issue should everything be resolved?

I'm not 100% sure, but you may reopen previously closed issue and when reapplying fix mention both issues.