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if statements support comptime known test error, runtime payload

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This commit is contained in:
Andrew Kelley 2018-02-08 22:18:13 -05:00
parent 54c06bf715
commit 0efe441dfd
3 changed files with 16 additions and 29 deletions
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23
TODO
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@ -1,25 +1,3 @@
sed -i 's/\(\bfn .*) \)%\(.*{\)$/\1!\2/g' $(find . -name "*.zig")
the literal translation of `%T` to this new code is `error!T`.
however this would not take advantage of error sets. It's
recommended to generally have all your functions which return possible
errors to use error set inference, like this:
fn foo() !void {
}
then you can return void, or any error, and the error set is inferred.
you can get the compiler to tell you the possible errors for an inferred error set like this:
foo() catch |err| switch (err) {};
test err should be comptime if error set has 0 members
comptime calling fn with inferred error set should give empty error set but still you can use try
comptime err to int of empty err set and of size 1 err set
@ -35,3 +13,4 @@ syntax - (error{}!void) as the return type
passing a fn()error{}!T to a fn()error!T should be a compile error, they're not compatible

11
src/ir.cpp
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@ -4800,12 +4800,8 @@ static IrInstruction *ir_gen_if_err_expr(IrBuilder *irb, Scope *scope, AstNode *
IrBasicBlock *else_block = ir_create_basic_block(irb, scope, "TryElse");
IrBasicBlock *endif_block = ir_create_basic_block(irb, scope, "TryEnd");
IrInstruction *is_comptime;
if (ir_should_inline(irb->exec, scope)) {
is_comptime = ir_build_const_bool(irb, scope, node, true);
} else {
is_comptime = ir_build_test_comptime(irb, scope, node, is_err);
}
bool force_comptime = ir_should_inline(irb->exec, scope);
IrInstruction *is_comptime = force_comptime ? ir_build_const_bool(irb, scope, node, true) : ir_build_test_comptime(irb, scope, node, is_err);
ir_build_cond_br(irb, scope, node, is_err, else_block, ok_block, is_comptime);
ir_set_cursor_at_end_and_append_block(irb, ok_block);
@ -4814,8 +4810,9 @@ static IrInstruction *ir_gen_if_err_expr(IrBuilder *irb, Scope *scope, AstNode *
if (var_symbol) {
IrInstruction *var_type = nullptr;
bool is_shadowable = false;
IrInstruction *var_is_comptime = force_comptime ? ir_build_const_bool(irb, scope, node, true) : ir_build_test_comptime(irb, scope, node, err_val);
VariableTableEntry *var = ir_create_var(irb, node, scope,
var_symbol, var_is_const, var_is_const, is_shadowable, is_comptime);
var_symbol, var_is_const, var_is_const, is_shadowable, var_is_comptime);
IrInstruction *var_ptr_value = ir_build_unwrap_err_payload(irb, scope, node, err_val_ptr, false);
IrInstruction *var_value = var_is_ptr ? var_ptr_value : ir_build_load_ptr(irb, scope, node, var_ptr_value);

11
test/cases/error.zig
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@ -123,3 +123,14 @@ fn testExplicitErrorSetCast(set1: Set1) void {
var y = Set1(x);
assert(y == error.A);
}
test "comptime test error for empty error set" {
testComptimeTestErrorEmptySet(1234);
comptime testComptimeTestErrorEmptySet(1234);
}
const EmptyErrorSet = error {};
fn testComptimeTestErrorEmptySet(x: EmptyErrorSet!i32) void {
if (x) |v| assert(v == 1234) else |err| @compileError("bad");
}