add equality for strings

compiler/builtins/bitcode/src/main.zig

@@ -23,6 +23,7 @@ comptime {
     exportStrFn(str.strConcatC, "concat");
     exportStrFn(str.strNumberOfBytes, "number_of_bytes");
     exportStrFn(str.strFromIntC, "from_int");
+    exportStrFn(str.strEqual, "equal");
 }
 
 // Export helpers - Must be run inside a comptime

compiler/builtins/bitcode/src/str.zig

@@ -260,6 +260,11 @@ pub const RocStr = extern struct {
     }
 };
 
+// Str.equal
+pub fn strEqual(self: RocStr, other: RocStr) callconv(.C) bool {
+    return self.eq(other);
+}
+
 // Str.numberOfBytes
 pub fn strNumberOfBytes(string: RocStr) callconv(.C) usize {
     return string.len();

compiler/builtins/src/bitcode.rs

@@ -31,3 +31,4 @@ pub const STR_STARTS_WITH: &str = "roc_builtins.str.starts_with";
 pub const STR_ENDS_WITH: &str = "roc_builtins.str.ends_with";
 pub const STR_NUMBER_OF_BYTES: &str = "roc_builtins.str.number_of_bytes";
 pub const STR_FROM_INT: &str = "roc_builtins.str.from_int";
+pub const STR_EQUAL: &str = "roc_builtins.str.equal";

compiler/gen/src/llvm/build_str.rs

@@ -77,6 +77,28 @@ fn str_symbol_to_i128<'a, 'ctx, 'env>(
         .into_int_value()
 }
 
+fn str_to_i128<'a, 'ctx, 'env>(
+    env: &Env<'a, 'ctx, 'env>,
+    value: BasicValueEnum<'ctx>,
+) -> IntValue<'ctx> {
+    let cell = env.builder.build_alloca(value.get_type(), "cell");
+
+    env.builder.build_store(cell, value);
+
+    let i128_ptr = env
+        .builder
+        .build_bitcast(
+            cell,
+            env.context.i128_type().ptr_type(AddressSpace::Generic),
+            "cast",
+        )
+        .into_pointer_value();
+
+    env.builder
+        .build_load(i128_ptr, "load_as_i128")
+        .into_int_value()
+}
+
 fn zig_str_to_struct<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
     zig_str: StructValue<'ctx>,
@@ -222,3 +244,19 @@ pub fn str_from_int<'a, 'ctx, 'env>(
 
     zig_str_to_struct(env, zig_result).into()
 }
+
+/// Str.equal : Str, Str -> Bool
+pub fn str_equal<'a, 'ctx, 'env>(
+    env: &Env<'a, 'ctx, 'env>,
+    value1: BasicValueEnum<'ctx>,
+    value2: BasicValueEnum<'ctx>,
+) -> BasicValueEnum<'ctx> {
+    let str1_i128 = str_to_i128(env, value1);
+    let str2_i128 = str_to_i128(env, value2);
+
+    call_bitcode_fn(
+        env,
+        &[str1_i128.into(), str2_i128.into()],
+        &bitcode::STR_EQUAL,
+    )
+}

compiler/gen/src/llvm/compare.rs

@@ -1,5 +1,6 @@
 use crate::llvm::build::Env;
-use inkwell::values::BasicValueEnum;
+use crate::llvm::build_str::str_equal;
+use inkwell::values::{BasicValueEnum, IntValue};
 use inkwell::{FloatPredicate, IntPredicate};
 use roc_mono::layout::{Builtin, Layout};
 
@@ -43,6 +44,7 @@ pub fn build_eq<'a, 'ctx, 'env>(
                 (Builtin::Int1, Builtin::Int1) => int_cmp(IntPredicate::EQ, "eq_i1"),
                 (Builtin::Float64, Builtin::Float64) => float_cmp(FloatPredicate::OEQ, "eq_f64"),
                 (Builtin::Float32, Builtin::Float32) => float_cmp(FloatPredicate::OEQ, "eq_f32"),
+                (Builtin::Str, Builtin::Str) => str_equal(env, lhs_val, rhs_val),
                 (b1, b2) => {
                     todo!("Handle equals for builtin layouts {:?} == {:?}", b1, b2);
                 }
@@ -95,6 +97,12 @@ pub fn build_neq<'a, 'ctx, 'env>(
                 (Builtin::Int1, Builtin::Int1) => int_cmp(IntPredicate::NE, "neq_i1"),
                 (Builtin::Float64, Builtin::Float64) => float_cmp(FloatPredicate::ONE, "neq_f64"),
                 (Builtin::Float32, Builtin::Float32) => float_cmp(FloatPredicate::ONE, "neq_f32"),
+                (Builtin::Str, Builtin::Str) => {
+                    let is_equal = str_equal(env, lhs_val, rhs_val).into_int_value();
+                    let result: IntValue = env.builder.build_not(is_equal, "negate");
+
+                    result.into()
+                }
                 (b1, b2) => {
                     todo!("Handle not equals for builtin layouts {:?} == {:?}", b1, b2);
                 }

compiler/gen/tests/gen_list.rs

@@ -415,25 +415,24 @@ mod gen_list {
         );
     }
 
-    //
-    // "panicked at 'not yet implemented: Handle equals for builtin layouts Str == Str'"
-    //
-    // #[test]
-    // fn list_keep_if_str_is_hello() {
-    //     assert_evals_to!(
-    //         indoc!(
-    //             r#"
-    //             strIsHello : Str -> Bool
-    //             strIsHello = \str ->
-    //                 str == "Hello"
-    //
-    //             List.keepIf ["Hello", "Hello", "Goodbye"] strIsHello
-    //             "#
-    //         ),
-    //         RocList::from_slice(&["Hello", "Hello"]),
-    //         RocList<&'static str>
-    //     );
-    // }
+    #[test]
+    #[ignore]
+    fn list_keep_if_str_is_hello() {
+        // keepIf causes a segfault with this function
+        assert_evals_to!(
+            indoc!(
+                r#"
+                 strIsHello : Str -> Bool
+                 strIsHello = \str ->
+                     str == "Hello"
+    
+                 List.keepIf ["Hello", "Hello", "Goodbye"] strIsHello
+                 "#
+            ),
+            RocList::from_slice(&["Hello", "Hello"]),
+            RocList<&'static str>
+        );
+    }
 
     #[test]
     fn list_map_on_empty_list_with_int_layout() {

compiler/gen/tests/gen_str.rs

@@ -514,4 +514,16 @@ mod gen_str {
         let min = format!("{}", i64::MIN);
         assert_evals_to!(r#"Str.fromInt Num.minInt"#, &min, &'static str);
     }
+
+    #[test]
+    fn str_equality() {
+        assert_evals_to!(r#""a" == "a""#, true, bool);
+        assert_evals_to!(
+            r#""loremipsumdolarsitamet" == "loremipsumdolarsitamet""#,
+            true,
+            bool
+        );
+        assert_evals_to!(r#""a" != "b""#, true, bool);
+        assert_evals_to!(r#""a" == "b""#, false, bool);
+    }
 }