Mesa (master): glsl: emit a specific error when ast_*_assign changes type

[Ilia Mirkin]

Module: Mesa
Branch: master
Commit: a32c87f74be1beed546d6d8853933d1b48f42f18
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=a32c87f74be1beed546d6d8853933d1b48f42f18

Author: Ilia Mirkin <imirkin at alum.mit.edu>
Date:   Fri Jul  8 23:28:22 2016 -0400

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 at alum.mit.edu>
Reviewed-by: Timothy Arceri <timothy.arceri at collabora.com>

---

 src/compiler/glsl/ast_to_hir.cpp | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index f189075..e03a6e3 100644
--- 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 =