glsl: emit a specific error when ast_*_assign changes type

For regular ast_add, we can implicitly change either a or b's type.
However in an assignment situation, the type of the lvalue is fixed. So
if the implicit conversion logic decides to change it, it means that the
rhs's type could not be converted to the lhs type.

Emit a specific error for this rather than the rather mysterious "is not
an lvalue" error that results from having a i2f or other operation as
the lvalue.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96729
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index f189075cc501fbfb02c1732c1e395f0c6c4cb4aa..e03a6e319f8d73a79e927bb044d676d6b037f2b6 100644 (file)
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -1355,7 +1355,7 @@ ast_expression::do_hir(exec_list *instructions,
    };
    ir_rvalue *result = NULL;
    ir_rvalue *op[3];
-   const struct glsl_type *type; /* a temporary variable for switch cases */
+   const struct glsl_type *type, *orig_type;
    bool error_emitted = false;
    YYLTYPE loc;
 
@@ -1645,10 +1645,18 @@ ast_expression::do_hir(exec_list *instructions,
       op[0] = this->subexpressions[0]->hir(instructions, state);
       op[1] = this->subexpressions[1]->hir(instructions, state);
 
+      orig_type = op[0]->type;
       type = arithmetic_result_type(op[0], op[1],
                                     (this->oper == ast_mul_assign),
                                     state, & loc);
 
+      if (type != orig_type) {
+         _mesa_glsl_error(& loc, state,
+                          "could not implicitly convert "
+                          "%s to %s", type->name, orig_type->name);
+         type = glsl_type::error_type;
+      }
+
       ir_rvalue *temp_rhs = new(ctx) ir_expression(operations[this->oper], type,
                                                    op[0], op[1]);
 
@@ -1672,8 +1680,16 @@ ast_expression::do_hir(exec_list *instructions,
       op[0] = this->subexpressions[0]->hir(instructions, state);
       op[1] = this->subexpressions[1]->hir(instructions, state);
 
+      orig_type = op[0]->type;
       type = modulus_result_type(op[0], op[1], state, &loc);
 
+      if (type != orig_type) {
+         _mesa_glsl_error(& loc, state,
+                          "could not implicitly convert "
+                          "%s to %s", type->name, orig_type->name);
+         type = glsl_type::error_type;
+      }
+
       assert(operations[this->oper] == ir_binop_mod);
 
       ir_rvalue *temp_rhs;
@@ -1713,7 +1729,17 @@ ast_expression::do_hir(exec_list *instructions,
       this->subexpressions[0]->set_is_lhs(true);
       op[0] = this->subexpressions[0]->hir(instructions, state);
       op[1] = this->subexpressions[1]->hir(instructions, state);
+
+      orig_type = op[0]->type;
       type = bit_logic_result_type(op[0], op[1], this->oper, state, &loc);
+
+      if (type != orig_type) {
+         _mesa_glsl_error(& loc, state,
+                          "could not implicitly convert "
+                          "%s to %s", type->name, orig_type->name);
+         type = glsl_type::error_type;
+      }
+
       ir_rvalue *temp_rhs = new(ctx) ir_expression(operations[this->oper],
                                                    type, op[0], op[1]);
       error_emitted =