[libcxx-commits] [PATCH] D155064: [clang][SemaCXX] Diagnose tautological uses of consteval if and is_constant_evaluated

[Takuya Shimizu via Phabricator via libcxx-commits]

hazohelet updated this revision to Diff 556946.
hazohelet added a comment.

After discussion in https://github.com/llvm/llvm-project/pull/66222, I noticed I had misunderstood the recursiveness of constant-evaluated context.
I was pushing constant-evaluating on the lambda body when it appears inside constant-evaluated context. This was causing false positive in

  constexpr auto cexpr_lambda = []() {
    return __builtin_is_constant_evaluated();
  }

I fixed this by stopping pushing constant-evaluated context (See `SemaLambda.cpp`). Instead, I am pushing immediate-function context when the outer evaluation context is immediate function context as well as when it's consteval lambda so that we can warn on

  consteval void f() {
  	auto lam = []() { return __builtin_is_constant_evaluated(); };
  }

@cor3ntin
Should this patch wait for https://github.com/llvm/llvm-project/pull/66222?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D155064/new/

https://reviews.llvm.org/D155064

Files:
  clang/docs/ReleaseNotes.rst
  clang/include/clang/Basic/DiagnosticASTKinds.td
  clang/include/clang/Basic/DiagnosticSemaKinds.td
  clang/include/clang/Parse/Parser.h
  clang/include/clang/Sema/Sema.h
  clang/lib/AST/ExprConstant.cpp
  clang/lib/Parse/ParseDecl.cpp
  clang/lib/Parse/ParseDeclCXX.cpp
  clang/lib/Parse/ParseExpr.cpp
  clang/lib/Parse/ParseExprCXX.cpp
  clang/lib/Parse/ParseStmt.cpp
  clang/lib/Sema/SemaChecking.cpp
  clang/lib/Sema/SemaDecl.cpp
  clang/lib/Sema/SemaDeclCXX.cpp
  clang/lib/Sema/SemaExpr.cpp
  clang/lib/Sema/SemaLambda.cpp
  clang/lib/Sema/SemaStmt.cpp
  clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
  clang/test/AST/Interp/builtins.cpp
  clang/test/AST/Interp/if.cpp
  clang/test/AST/Interp/literals.cpp
  clang/test/CXX/expr/expr.const/p2-0x.cpp
  clang/test/CXX/expr/expr.const/p6-2a.cpp
  clang/test/CXX/expr/expr.prim/expr.prim.lambda/p3.cpp
  clang/test/CXX/stmt.stmt/stmt.select/stmt.if/p4.cpp
  clang/test/Parser/pragma-fenv_access.c
  clang/test/SemaCXX/constant-conversion.cpp
  clang/test/SemaCXX/constant-expression-cxx11.cpp
  clang/test/SemaCXX/cxx2a-consteval.cpp
  clang/test/SemaCXX/cxx2b-consteval-if.cpp
  clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
  clang/test/SemaCXX/fixit-tautological-meta-constant.cpp
  clang/test/SemaCXX/vartemplate-lambda.cpp
  clang/test/SemaCXX/warn-constant-evaluated-constexpr.cpp
  clang/test/SemaCXX/warn-tautological-meta-constant.cpp
  clang/test/SemaTemplate/concepts.cpp
  clang/unittests/Support/TimeProfilerTest.cpp
  libcxx/include/__type_traits/is_constant_evaluated.h
  libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/ranges.copy.segmented.pass.cpp
  libcxx/test/std/utilities/meta/meta.const.eval/is_constant_evaluated.verify.cpp

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