[Mesa-dev] [PATCH 1/4] glsl: fix visit/visit_enter overloaded virtual function warnings

[Ian Romanick]

I don't understand these warnings, and I have even less understanding of
how "using" fixes them.  For example...

On 05/30/2017 01:47 PM, Rob Herring wrote:
> clang gives warnings about overloaded virtual functions:
> 
> src/compiler/glsl/linker.cpp:244:30: warning: '(anonymous namespace)::array_resize_visitor::visit' hides overloaded virtual function [-Woverloaded-virtual]
>    virtual ir_visitor_status visit(ir_variable *var)
>                              ^
> src/compiler/glsl/linker.cpp:195:30: note: hidden overloaded virtual function '(anonymous namespace)::deref_type_updater::visit' declared here: type mismatch at 1st parameter ('ir_dereference_variable *' vs 'ir_variable *')
>    virtual ir_visitor_status visit(ir_dereference_variable *ir)
>                              ^

This is weird and confusing.  ir_hierarchical_visitor has a virtual
visit(class ir_dereference_variable *) method.  The complaint about the
type seems... bizarre.

> src/compiler/glsl/linker.cpp:1414:30: warning: 'array_sizing_visitor::visit' hides overloaded virtual function [-Woverloaded-virtual]
>    virtual ir_visitor_status visit(ir_variable *var)
>                              ^
> src/compiler/glsl/linker.cpp:195:30: note: hidden overloaded virtual function '(anonymous namespace)::deref_type_updater::visit' declared here: type mismatch at 1st parameter ('ir_dereference_variable *' vs 'ir_variable *')
>    virtual ir_visitor_status visit(ir_dereference_variable *ir)
>                              ^
> src/compiler/glsl/lower_jumps.cpp:395:17: warning: '(anonymous namespace)::ir_lower_jumps_visitor::visit' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual void visit(class ir_loop_jump * ir)
>                 ^
> src/compiler/glsl/lower_jumps.cpp:417:17: warning: '(anonymous namespace)::ir_lower_jumps_visitor::visit' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual void visit(class ir_return * ir)
>                 ^
> src/compiler/glsl/lower_jumps.cpp:439:17: warning: '(anonymous namespace)::ir_lower_jumps_visitor::visit' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual void visit(class ir_discard * ir)
>                 ^
> src/compiler/glsl/lower_jumps.cpp:519:17: warning: '(anonymous namespace)::ir_lower_jumps_visitor::visit' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual void visit(ir_if *ir)
>                 ^
> src/compiler/glsl/lower_jumps.cpp:835:17: warning: '(anonymous namespace)::ir_lower_jumps_visitor::visit' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual void visit(ir_loop *ir)
>                 ^
> src/compiler/glsl/lower_jumps.cpp:963:17: warning: '(anonymous namespace)::ir_lower_jumps_visitor::visit' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual void visit(ir_function_signature *ir)
>                 ^
> src/compiler/glsl/lower_jumps.cpp:1009:17: warning: '(anonymous namespace)::ir_lower_jumps_visitor::visit' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual void visit(class ir_function * ir)
>                 ^
> src/compiler/glsl/opt_constant_variable.cpp:52:30: warning: '(anonymous namespace)::ir_constant_variable_visitor::visit_enter' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual ir_visitor_status visit_enter(ir_dereference_variable *);
>                              ^
> src/compiler/glsl/opt_dead_code_local.cpp:101:30: warning: '(anonymous namespace)::kill_for_derefs_visitor::visit' hides overloaded virtual functions [-Woverloaded-virtual]
>    virtual ir_visitor_status visit(ir_swizzle *ir)
>                              ^
> 
> Fix these with the "using" directive.
> 
> Signed-off-by: Rob Herring <robh at kernel.org>
> ---
>  src/compiler/glsl/linker.cpp                | 2 ++
>  src/compiler/glsl/lower_jumps.cpp           | 1 +
>  src/compiler/glsl/opt_constant_variable.cpp | 2 ++
>  src/compiler/glsl/opt_dead_code_local.cpp   | 1 +
>  4 files changed, 6 insertions(+)
> 
> diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
> index 2e7dd2b87356..3aa95b734321 100644
> --- a/src/compiler/glsl/linker.cpp
> +++ b/src/compiler/glsl/linker.cpp
> @@ -241,6 +241,7 @@ public:
>        /* empty */
>     }
>  
> +   using ir_hierarchical_visitor::visit;
>     virtual ir_visitor_status visit(ir_variable *var)
>     {
>        if (!var->type->is_array() || var->data.mode != ir_var_shader_in ||
> @@ -1411,6 +1412,7 @@ public:
>        ralloc_free(this->mem_ctx);
>     }
>  
> +   using ir_hierarchical_visitor::visit;
>     virtual ir_visitor_status visit(ir_variable *var)
>     {
>        const glsl_type *type_without_array;
> diff --git a/src/compiler/glsl/lower_jumps.cpp b/src/compiler/glsl/lower_jumps.cpp
> index 7dc34056a1b1..0cb55127a6e6 100644
> --- a/src/compiler/glsl/lower_jumps.cpp
> +++ b/src/compiler/glsl/lower_jumps.cpp
> @@ -392,6 +392,7 @@ struct ir_lower_jumps_visitor : public ir_control_flow_visitor {
>        }
>     }
>  
> +   using ir_visitor::visit;
>     virtual void visit(class ir_loop_jump * ir)
>     {
>        /* Eliminate all instructions after each one, since they are
> diff --git a/src/compiler/glsl/opt_constant_variable.cpp b/src/compiler/glsl/opt_constant_variable.cpp
> index 1c06ffe6750a..db91cac1589d 100644
> --- a/src/compiler/glsl/opt_constant_variable.cpp
> +++ b/src/compiler/glsl/opt_constant_variable.cpp
> @@ -50,7 +50,9 @@ struct assignment_entry {
>  class ir_constant_variable_visitor : public ir_hierarchical_visitor {
>  public:
>     virtual ir_visitor_status visit_enter(ir_dereference_variable *);
> +   using ir_hierarchical_visitor::visit;
>     virtual ir_visitor_status visit(ir_variable *);
> +   using ir_hierarchical_visitor::visit_enter;
>     virtual ir_visitor_status visit_enter(ir_assignment *);
>     virtual ir_visitor_status visit_enter(ir_call *);
>  
> diff --git a/src/compiler/glsl/opt_dead_code_local.cpp b/src/compiler/glsl/opt_dead_code_local.cpp
> index a4038794c6bf..f5ea4ae3d537 100644
> --- a/src/compiler/glsl/opt_dead_code_local.cpp
> +++ b/src/compiler/glsl/opt_dead_code_local.cpp
> @@ -91,6 +91,7 @@ public:
>        }
>     }
>  
> +   using ir_hierarchical_visitor::visit;
>     virtual ir_visitor_status visit(ir_dereference_variable *ir)
>     {
>        use_channels(ir->var, ~0);
>