[Bug c/64279] Warning missing for "(cond) ? A : A" / if(cond) expr1; else expr1; // same expression in if and else branch

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64279

--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Fri Jan 20 12:02:50 2017
New Revision: 244705

URL: https://gcc.gnu.org/viewcvs?rev=244705&root=gcc&view=rev
Log:
        PR c/64279
        * c-common.h (do_warn_duplicated_branches_r): Declare.
        * c-gimplify.c (c_genericize): Walk the function tree calling
        do_warn_duplicated_branches_r.
        * c-warn.c (expr_from_macro_expansion_r): New.
        (do_warn_duplicated_branches): New.
        (do_warn_duplicated_branches_r): New.
        * c.opt (Wduplicated-branches): New option.

        * c-typeck.c (build_conditional_expr): Warn about duplicated branches.

        * call.c (build_conditional_expr_1): Warn about duplicated branches.
        * semantics.c (finish_expr_stmt): Build statement using the proper
        location.

        * doc/invoke.texi: Document -Wduplicated-branches.
        * fold-const.c (operand_equal_p): Handle MODIFY_EXPR, INIT_EXPR,
        COMPOUND_EXPR, PREDECREMENT_EXPR, PREINCREMENT_EXPR,
        POSTDECREMENT_EXPR, POSTINCREMENT_EXPR, CLEANUP_POINT_EXPR, EXPR_STMT,
        STATEMENT_LIST, and RETURN_EXPR.  For non-pure non-const functions
        return 0 only when not OEP_LEXICOGRAPHIC.
        (fold_build_cleanup_point_expr): Use the expression
        location when building CLEANUP_POINT_EXPR.
        * tree-core.h (enum operand_equal_flag): Add OEP_LEXICOGRAPHIC.
        * tree.c (add_expr): Handle error_mark_node.

        * c-c++-common/Wduplicated-branches-1.c: New test.
        * c-c++-common/Wduplicated-branches-10.c: New test.
        * c-c++-common/Wduplicated-branches-11.c: New test.
        * c-c++-common/Wduplicated-branches-12.c: New test.
        * c-c++-common/Wduplicated-branches-2.c: New test.
        * c-c++-common/Wduplicated-branches-3.c: New test.
        * c-c++-common/Wduplicated-branches-4.c: New test.
        * c-c++-common/Wduplicated-branches-5.c: New test.
        * c-c++-common/Wduplicated-branches-6.c: New test.
        * c-c++-common/Wduplicated-branches-7.c: New test.
        * c-c++-common/Wduplicated-branches-8.c: New test.
        * c-c++-common/Wduplicated-branches-9.c: New test.
        * c-c++-common/Wimplicit-fallthrough-7.c: Coalesce dg-warning.
        * g++.dg/cpp0x/lambda/lambda-switch.C: Move dg-warning.
        * g++.dg/ext/builtin-object-size3.C: Likewise.
        * g++.dg/gomp/loop-1.C: Likewise.
        * g++.dg/warn/Wduplicated-branches1.C: New test.
        * g++.dg/warn/Wduplicated-branches2.C: New test.

Added:
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-1.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-10.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-11.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-12.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-2.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-3.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-4.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-5.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-6.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-7.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-8.c
    trunk/gcc/testsuite/c-c++-common/Wduplicated-branches-9.c
    trunk/gcc/testsuite/g++.dg/warn/Wduplicated-branches1.C
    trunk/gcc/testsuite/g++.dg/warn/Wduplicated-branches2.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-common.h
    trunk/gcc/c-family/c-gimplify.c
    trunk/gcc/c-family/c-warn.c
    trunk/gcc/c-family/c.opt
    trunk/gcc/c/ChangeLog
    trunk/gcc/c/c-typeck.c
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/call.c
    trunk/gcc/cp/semantics.c
    trunk/gcc/doc/invoke.texi
    trunk/gcc/fold-const.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/c-c++-common/Wimplicit-fallthrough-7.c
    trunk/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-switch.C
    trunk/gcc/testsuite/g++.dg/ext/builtin-object-size3.C
    trunk/gcc/testsuite/g++.dg/gomp/loop-1.C
    trunk/gcc/tree-core.h
    trunk/gcc/tree.c