[all-commits] [llvm/llvm-project] cbbf2e: Diagnose -Wunused-value based on CFG reachability

[Yuanfang Chen via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: cbbf2e8c8ae7730ff0121f4868de4a7d188feb65
      https://github.com/llvm/llvm-project/commit/cbbf2e8c8ae7730ff0121f4868de4a7d188feb65
  Author: Yuanfang Chen <yuanfang.chen at sony.com>
  Date:   2021-09-22 (Wed, 22 Sep 2021)

  Changed paths:
    M clang/include/clang/Basic/DiagnosticSemaKinds.td
    M clang/include/clang/Sema/Sema.h
    M clang/lib/Sema/SemaExpr.cpp
    M clang/lib/Sema/SemaExprCXX.cpp
    M clang/lib/Sema/SemaStmt.cpp
    M clang/test/Analysis/dead-stores.c
    M clang/test/CXX/basic/basic.link/p8.cpp
    M clang/test/CXX/drs/dr14xx.cpp
    M clang/test/CXX/drs/dr20xx.cpp
    M clang/test/CXX/drs/dr7xx.cpp
    M clang/test/CXX/temp/temp.constr/temp.constr.constr/partial-specializations.cpp
    M clang/test/CodeCompletion/pragma-macro-token-caching.c
    M clang/test/Frontend/fixed_point_crash.c
    M clang/test/PCH/cxx-explicit-specifier.cpp
    M clang/test/Parser/cxx-ambig-decl-expr.cpp
    M clang/test/Parser/cxx0x-ambig.cpp
    M clang/test/Parser/cxx1z-init-statement.cpp
    M clang/test/Parser/objc-messaging-1.m
    M clang/test/Parser/objc-try-catch-1.m
    M clang/test/Parser/objcxx11-attributes.mm
    M clang/test/Sema/const-eval.c
    M clang/test/Sema/exprs.c
    M clang/test/Sema/i-c-e.c
    M clang/test/Sema/sizeless-1.c
    M clang/test/Sema/switch-1.c
    M clang/test/Sema/vla-2.c
    M clang/test/Sema/warn-type-safety.c
    M clang/test/Sema/warn-unused-value.c
    M clang/test/SemaCXX/attr-annotate.cpp
    M clang/test/SemaCXX/builtin-constant-p.cpp
    M clang/test/SemaCXX/constant-expression-cxx2a.cpp
    M clang/test/SemaCXX/constant-expression.cpp
    M clang/test/SemaCXX/expression-traits.cpp
    M clang/test/SemaCXX/matrix-type-operators.cpp
    M clang/test/SemaCXX/overloaded-operator.cpp
    M clang/test/SemaCXX/sizeless-1.cpp
    M clang/test/SemaCXX/vector.cpp
    M clang/test/SemaCXX/warn-comma-operator.cpp
    M clang/test/SemaCXX/warn-unused-value.cpp
    M clang/test/SemaTemplate/derived.cpp
    M clang/test/SemaTemplate/lambda-capture-pack.cpp

  Log Message:
  -----------
  Diagnose -Wunused-value based on CFG reachability

While at it, add the diagnosis message "left operand of comma operator has no effect" (used by GCC) for comma operator.

This also makes Clang diagnose in the constant evaluation context which aligns with GCC/MSVC behavior. (https://godbolt.org/z/7zxb8Tx96)

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D103938