[all-commits] [llvm/llvm-project] 27a972: Diagnose -Wunused-value based on CFG reachability

[Yuanfang Chen via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 27a972a699cd875c7fa9114dc0888015cd724f31
      https://github.com/llvm/llvm-project/commit/27a972a699cd875c7fa9114dc0888015cd724f31
  Author: Yuanfang Chen <yuanfang.chen at sony.com>
  Date:   2021-09-28 (Tue, 28 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

(This relands 59337263ab45d7657e and makes sure comma operator
 diagnostics are suppressed in a SFINAE context.)

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