feat(Str.toNum): support decimal

compiler/builtins/bitcode/src/dec.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 const str = @import("str.zig");
+const num_ = @import("num.zig");
 const utils = @import("utils.zig");
 
 const math = std.math;
@@ -1052,6 +1053,14 @@ test "div: 10 / 3" {
 
 // exports
 
+pub fn fromStr(arg: RocStr) callconv(.C) num_.NumParseResult(i128) {
+    if (@call(.{ .modifier = always_inline }, RocDec.fromStr, .{arg})) |dec| {
+        return .{ .errorcode = 0, .value = dec.num };
+    } else {
+        return .{ .errorcode = 1, .value = 0 };
+    }
+}
+
 pub fn fromF64C(arg: f64) callconv(.C) i128 {
     return if (@call(.{ .modifier = always_inline }, RocDec.fromF64, .{arg})) |dec| dec.num else @panic("TODO runtime exception failing convert f64 to RocDec");
 }

compiler/builtins/bitcode/src/main.zig

@@ -10,6 +10,7 @@ const STR = "str";
 const dec = @import("dec.zig");
 
 comptime {
+    exportDecFn(dec.fromStr, "from_str");
     exportDecFn(dec.fromF64C, "from_f64");
     exportDecFn(dec.eqC, "eq");
     exportDecFn(dec.neqC, "neq");

compiler/builtins/src/bitcode.rs

@@ -302,6 +302,7 @@ pub const LIST_ANY: &str = "roc_builtins.list.any";
 pub const LIST_ALL: &str = "roc_builtins.list.all";
 pub const LIST_FIND_UNSAFE: &str = "roc_builtins.list.find_unsafe";
 
+pub const DEC_FROM_STR: &str = "roc_builtins.dec.from_str";
 pub const DEC_FROM_F64: &str = "roc_builtins.dec.from_f64";
 pub const DEC_EQ: &str = "roc_builtins.dec.eq";
 pub const DEC_NEQ: &str = "roc_builtins.dec.neq";

compiler/gen_llvm/src/llvm/build.rs

@@ -5281,7 +5281,7 @@ fn run_low_level<'a, 'ctx, 'env>(
                     Layout::Builtin(Builtin::Float(float_width)) => {
                         &bitcode::STR_TO_FLOAT[float_width]
                     }
-                    Layout::Builtin(Builtin::Decimal) => bitcode::STR_TO_DECIMAL,
+                    Layout::Builtin(Builtin::Decimal) => bitcode::DEC_FROM_STR,
                     _ => unreachable!(),
                 };
 

compiler/test_gen/src/gen_str.rs

@@ -1331,3 +1331,25 @@ fn str_to_num_float() {
         f64
     );
 }
+
+#[test]
+#[cfg(any(feature = "gen-llvm"))]
+fn str_to_num_dec() {
+    use roc_std::RocDec;
+
+    assert_evals_to!(
+        indoc!(
+            r#"
+            x : Dec
+            x = 2.0
+
+            when Str.toNum "1.0" is
+                Ok n -> n + x
+                Err _ -> 0
+
+            "#
+        ),
+        RocDec::from_str("3.0").unwrap(),
+        RocDec
+    );
+}