re PR c++/92024 (crash in check_local_shadow)

2019-10-30  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * doc/invoke.texi (-Wshadow, -Wshadow=global
        -Wshadow=local, -Wshadow=compatible-local): Update documentation.

cp:
2019-10-30  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR c++/92024
        * name-lookup.c (check_local_shadow): Shadowing TYPE_DECLs
        is always a -Wshadow=compatible-local warning, unless
        -Wshadow is used.

testsuite:
2019-10-30  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR c++/92024
        * g++.dg/parse/crash70.C: New test.
        * c-c++-common/Wshadow-1.c: New test.

From-SVN: r277643

1 files changed, 17 insertions, 15 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 1407d01..d1eb317 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -342,7 +342,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wno-pragmas  -Wno-prio-ctor-dtor  -Wredundant-decls @gol
 -Wrestrict  -Wno-return-local-addr @gol
 -Wreturn-type  -Wsequence-point  -Wshadow  -Wno-shadow-ivar @gol
--Wshadow=global,  -Wshadow=local,  -Wshadow=compatible-local @gol
+-Wshadow=global  -Wshadow=local  -Wshadow=compatible-local @gol
 -Wshift-overflow  -Wshift-overflow=@var{n} @gol
 -Wshift-count-negative  -Wshift-count-overflow  -Wshift-negative-value @gol
 -Wsign-compare  -Wsign-conversion  -Wfloat-conversion @gol
@@ -6309,7 +6309,7 @@ can be used to suppress such a warning.
 @opindex Wno-discarded-array-qualifiers
 @opindex Wdiscarded-array-qualifiers
 Do not warn if type qualifiers on arrays which are pointer targets
-are being discarded. Typically, the compiler warns if a
+are being discarded.  Typically, the compiler warns if a
 @code{const int (*)[]} variable is passed to a function that
 takes a @code{int (*)[]} parameter.  This option can be used to
 suppress such a warning.
@@ -6508,9 +6508,13 @@ allowed in GCC@.  It is not supported by ISO C90.  @xref{Mixed Declarations}.
 @opindex Wno-shadow
 Warn whenever a local variable or type declaration shadows another
 variable, parameter, type, class member (in C++), or instance variable
-(in Objective-C) or whenever a built-in function is shadowed. Note
+(in Objective-C) or whenever a built-in function is shadowed.  Note
 that in C++, the compiler warns if a local variable shadows an
 explicit typedef, but not if it shadows a struct/class/enum.
+If this warning is enabled, it includes also all instances of
+local shadowing.  This means that @option{-Wno-shadow=local}
+and @option{-Wno-shadow=compatible-local} are ignored when
+@option{-Wshadow} is used.
 Same as @option{-Wshadow=global}.
 
 @item -Wno-shadow-ivar @r{(Objective-C only)}
@@ -6521,20 +6525,19 @@ Objective-C method.
 
 @item -Wshadow=global
 @opindex Wshadow=global
-The default for @option{-Wshadow}. Warns for any (global) shadowing.
-This warning is enabled by @option{-Wshadow=global}.
+Warn for any shadowing.
+Same as @option{-Wshadow}.
 
 @item -Wshadow=local
 @opindex Wshadow=local
 Warn when a local variable shadows another local variable or parameter.
-This warning is enabled by @option{-Wshadow=local}.
 
 @item -Wshadow=compatible-local
 @opindex Wshadow=compatible-local
 Warn when a local variable shadows another local variable or parameter
-whose type is compatible with that of the shadowing variable. In C++,
+whose type is compatible with that of the shadowing variable.  In C++,
 type compatibility here means the type of the shadowing variable can be
-converted to that of the shadowed variable. The creation of this flag
+converted to that of the shadowed variable.  The creation of this flag
 (in addition to @option{-Wshadow=local}) is based on the idea that when
 a local variable shadows another one of incompatible type, it is most
 likely intentional, not a bug or typo, as shown in the following example:
@@ -6553,16 +6556,15 @@ for (SomeIterator i = SomeObj.begin(); i != SomeObj.end(); ++i)
 @end smallexample
 
 Since the two variable @code{i} in the example above have incompatible types,
-enabling only @option{-Wshadow=compatible-local} will not emit a warning.
+enabling only @option{-Wshadow=compatible-local} does not emit a warning.
 Because their types are incompatible, if a programmer accidentally uses one
-in place of the other, type checking will catch that and emit an error or
-warning. So not warning (about shadowing) in this case will not lead to
-undetected bugs. Use of this flag instead of @option{-Wshadow=local} can
+in place of the other, type checking is expected to catch that and emit an
+error or warning.  Use of this flag instead of @option{-Wshadow=local} can
 possibly reduce the number of warnings triggered by intentional shadowing.
-Note that this does also mean that shadowing @code{const char *i} by
-@code{char *i} will not emit a warning.
+Note that this also means that shadowing @code{const char *i} by
+@code{char *i} does not emit a warning.
 
-This warning is enabled by @option{-Wshadow=compatible-local}.
+This warning is also enabled by @option{-Wshadow=local}.
 
 @item -Wlarger-than=@var{byte-size}
 @opindex Wlarger-than=