invoke.texi: Document the -Wsizeof-pointer-div warning.

gcc:
2017-06-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * doc/invoke.texi: Document the -Wsizeof-pointer-div warning.

gcc/c-family:
2017-06-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c.opt (Wsizeof-pointer-div): New warning option.

gcc/c:
2017-06-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c-parser.c (c_parser_binary_expression): Implement the
        -Wsizeof_pointer_div warning.
        (c_parser_postfix_expression): Allow SIZEOF_EXPR as expr.original_code
        from a parenthesized expression.
        (c_parser_expr_list): Use c_last_sizeof_loc.
        * c-tree.h (c_last_sizeof_loc): New external.
        * c-typeck.c (c_last_sizeof_loc): New variable.
        (c_expr_sizeof_expr, c_expr_sizeof_type): Assign c_last_sizeof_loc.

gcc/cp:
2017-06-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * typeck.c (cp_build_binary_op): Implement the -Wsizeof_pointer_div
        warning.

gcc/testsuite:
2017-06-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * c-c++-common/Wsizeof-pointer-div.c: New test. 
        * gcc.dg/Wsizeof-pointer-memaccess1.c: Add test cases with parens.
        * gcc.dg/torture/Wsizeof-pointer-memaccess1.c: Likewise.
        * gcc.target/i386/sse-init-v4hi-1.c: Fix test case.
        * gcc.target/i386/sse-init-v4sf-1.c: Likewise.
        * gcc.target/i386/sse-set-ps-1.c: Likewise.
        * gcc.target/i386/sse2-init-v16qi-1.c: Likewise.
        * gcc.target/i386/sse2-init-v2di-1.c: Likewise.
        * gcc.target/i386/sse2-init-v4si-1.c: Likewise.
        * gcc.target/i386/sse2-init-v8hi-1.c: Likewise.
        * gcc.target/i386/sse2-set-epi32-1.c: Likewise.
        * gcc.target/i386/sse2-set-epi64x-1.c: Likewise.
        * gcc.target/i386/sse4_1-init-v16qi-1.c: Likewise.
        * gcc.target/i386/sse4_1-init-v2di-1.c: Likewise.
        * gcc.target/i386/sse4_1-init-v4sf-1.c: Likewise.
        * gcc.target/i386/sse4_1-init-v4si-1.c: Likewise.
        * gcc.target/i386/sse4_1-set-epi32-1.c: Likewise.
        * gcc.target/i386/sse4_1-set-epi64x-1.c: Likewise.
        * gcc.target/i386/sse4_1-set-ps-1.c: Likewise.
        * libgomp.c/pr39591-2.c: Likewise.
        * libgomp.c/pr39591-3.c: Likewise.

From-SVN: r248811

1 files changed, 11 insertions, 1 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 59563aa..819e800 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -306,7 +306,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wshift-overflow  -Wshift-overflow=@var{n} @gol
 -Wshift-count-negative  -Wshift-count-overflow  -Wshift-negative-value @gol
 -Wsign-compare  -Wsign-conversion  -Wfloat-conversion @gol
--Wno-scalar-storage-order @gol
+-Wno-scalar-storage-order  -Wsizeof-pointer-div @gol
 -Wsizeof-pointer-memaccess  -Wsizeof-array-argument @gol
 -Wstack-protector  -Wstack-usage=@var{len}  -Wstrict-aliasing @gol
 -Wstrict-aliasing=n  -Wstrict-overflow  -Wstrict-overflow=@var{n} @gol
@@ -3832,6 +3832,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect Options}.
 -Wreturn-type  @gol
 -Wsequence-point  @gol
 -Wsign-compare @r{(only in C++)}  @gol
+-Wsizeof-pointer-div @gol
 -Wsizeof-pointer-memaccess @gol
 -Wstrict-aliasing  @gol
 -Wstrict-overflow=1  @gol
@@ -6093,6 +6094,15 @@ void operator delete[] (void *, std::size_t) noexcept;
 or vice versa.  Enabled by @option{-Wextra} along with
 @option{-fsized-deallocation}.
 
+@item -Wsizeof-pointer-div
+@opindex Wsizeof-pointer-div
+@opindex Wno-sizeof-pointer-div
+Warn for suspicious divisions of two sizeof expressions that divide
+the pointer size by the element size, which is the usual way to compute
+the array size but won't work out correctly with pointers.  This warning
+warns e.g.@: about @code{sizeof (ptr) / sizeof (ptr[0])} if @code{ptr} is
+not an array, but a pointer.  This warning is enabled by @option{-Wall}.
+
 @item -Wsizeof-pointer-memaccess
 @opindex Wsizeof-pointer-memaccess
 @opindex Wno-sizeof-pointer-memaccess