>From section 4.1.9 (Arrays) of the GLSL 4.40 spec (as of revision 7): However, unless noted otherwise, blocks cannot be redeclared; an unsized array in a user-declared block cannot be sized through redeclaration.
The only place where the spec notes that interface blocks can be redeclared is to allow for redeclaration of built-in interface blocks such as gl_PerVertex. Therefore, user-defined interface blocks can never be redeclared. This is a clarification of previous intent (see Khronos bug 10659: https://cvs.khronos.org/bugzilla/show_bug.cgi?id=10659). We were already preventing interface block redeclaration using the same block name at compile time, but we weren't preventing interface block redeclaration using the same instance name (and different block names) at compile time. And we weren't preventing an instance name from conflicting with a previously-declared ordinary variable. In practice the problem would be caught at link time, but only because of a coincidence: since ast_interface_block::hir() wasn't doing any checking to see if the instance name already existed in the shader, it was creating a second ir_variable in the shader having the same name but a different type. Coincidentally, when the linker checked for intrastage consistency of global variable declarations, it treated the two declarations from the same shader as a conflict, so it reported a link error. But it seems dangerous to rely on that linker behaviour to catch illegal redeclarations that really ought to be detected at compile time. --- src/glsl/ast_to_hir.cpp | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp index c8a38e7..f44e97d 100644 --- a/src/glsl/ast_to_hir.cpp +++ b/src/glsl/ast_to_hir.cpp @@ -4813,8 +4813,14 @@ ast_interface_block::hir(exec_list *instructions, var->init_interface_type(block_type); if (state->target == geometry_shader && var_mode == ir_var_shader_in) handle_geometry_shader_input_decl(state, loc, var); - state->symbols->add_variable(var); - instructions->push_tail(var); + + if (state->symbols->get_variable(this->instance_name)) { + _mesa_glsl_error(&loc, state, "`%s' redeclared", this->instance_name); + delete var; + } else { + state->symbols->add_variable(var); + instructions->push_tail(var); + } } else { /* In order to have an array size, the block must also be declared with * an instane name. -- 1.8.4 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev