fix: fixes issue #228

crates/mun_codegen/src/ir/body.rs

@@ -488,8 +488,12 @@ impl<'a, 'b, D: IrDatabase> BodyIrGenerator<'a, 'b, D> {
                 }
             };
         }
-        tail.and_then(|expr| self.gen_expr(expr))
-            .or_else(|| Some(self.gen_empty()))
+
+        if let Some(tail) = tail {
+            self.gen_expr(tail)
+        } else {
+            Some(self.gen_empty())
+        }
     }
 
     /// Constructs a builder that should be used to emit an `alloca` instruction. These instructions
@@ -1105,7 +1109,7 @@ impl<'a, 'b, D: IrDatabase> BodyIrGenerator<'a, 'b, D> {
             if !self.infer[*else_branch].is_never() {
                 self.builder.build_unconditional_branch(&merge_block);
             }
-            result_ir.map(|res| (res, self.builder.get_insert_block().unwrap()))
+            Some((result_ir, self.builder.get_insert_block().unwrap()))
         } else {
             None
         };
@@ -1117,13 +1121,15 @@ impl<'a, 'b, D: IrDatabase> BodyIrGenerator<'a, 'b, D> {
 
         // Construct phi block if a value was returned
         if let Some(then_block_ir) = then_block_ir {
-            if let Some((else_block_ir, else_block)) = else_ir_and_block {
+            if let Some((Some(else_block_ir), else_block)) = else_ir_and_block {
                 let phi = self.builder.build_phi(then_block_ir.get_type(), "iftmp");
                 phi.add_incoming(&[(&then_block_ir, &then_block), (&else_block_ir, &else_block)]);
                 Some(phi.as_basic_value())
             } else {
                 Some(then_block_ir)
             }
+        } else if let Some((else_block_ir, _else_block)) = else_ir_and_block {
+            else_block_ir
         } else {
             Some(self.gen_empty())
         }

crates/mun_codegen/src/snapshots/test__issue_228.snap

@@ -0,0 +1,38 @@
+---
+source: crates/mun_codegen/src/test.rs
+expression: "pub  fn fact(n: usize) -> usize {\n   \t    if n == 0 {return 1} else {n * (n-1)}\n}"
+---
+; == FILE IR =====================================
+; ModuleID = 'main.mun'
+source_filename = "main.mun"
+
+%struct.MunTypeInfo = type { [16 x i8], i8*, i32, i8, i8 }
+
+@global_type_table = external global [1 x %struct.MunTypeInfo*]
+
+define i64 @fact(i64) {
+body:
+  %eq = icmp eq i64 %0, 0
+  br i1 %eq, label %then, label %else
+
+then:                                             ; preds = %else, %body
+  %merge = phi i64 [ 1, %body ], [ %mul, %else ]
+  ret i64 %merge
+
+else:                                             ; preds = %body
+  %sub = sub i64 %0, 1
+  %mul = mul i64 %0, %sub
+  br label %then
+}
+
+
+; == GROUP IR ====================================
+; ModuleID = 'group_name'
+source_filename = "group_name"
+
+%struct.MunTypeInfo = type { [16 x i8], i8*, i32, i8, i8 }
+
+@"type_info::<core::u64>::name" = private unnamed_addr constant [10 x i8] c"core::u64\00"
+@"type_info::<core::u64>" = private unnamed_addr constant %struct.MunTypeInfo { [16 x i8] c"\A6\E7g \D1\8B\1Aq`\1F\1E\07\BB5@q", [10 x i8]* @"type_info::<core::u64>::name", i32 64, i8 8, i8 0 }
+@global_type_table = constant [1 x %struct.MunTypeInfo*] [%struct.MunTypeInfo* @"type_info::<core::u64>"]
+

crates/mun_codegen/src/snapshots/test__issue_228_never_if.snap

@@ -0,0 +1,37 @@
+---
+source: crates/mun_codegen/src/test.rs
+expression: "pub  fn fact(n: usize) -> usize {\n   \t    if n == 0 {return 1} else {return n * (n-1)}\n   \t    return 2;\n}"
+---
+; == FILE IR =====================================
+; ModuleID = 'main.mun'
+source_filename = "main.mun"
+
+%struct.MunTypeInfo = type { [16 x i8], i8*, i32, i8, i8 }
+
+@global_type_table = external global [1 x %struct.MunTypeInfo*]
+
+define i64 @fact(i64) {
+body:
+  %eq = icmp eq i64 %0, 0
+  br i1 %eq, label %then, label %else
+
+then:                                             ; preds = %body
+  ret i64 1
+
+else:                                             ; preds = %body
+  %sub = sub i64 %0, 1
+  %mul = mul i64 %0, %sub
+  ret i64 %mul
+}
+
+
+; == GROUP IR ====================================
+; ModuleID = 'group_name'
+source_filename = "group_name"
+
+%struct.MunTypeInfo = type { [16 x i8], i8*, i32, i8, i8 }
+
+@"type_info::<core::u64>::name" = private unnamed_addr constant [10 x i8] c"core::u64\00"
+@"type_info::<core::u64>" = private unnamed_addr constant %struct.MunTypeInfo { [16 x i8] c"\A6\E7g \D1\8B\1Aq`\1F\1E\07\BB5@q", [10 x i8]* @"type_info::<core::u64>::name", i32 64, i8 8, i8 0 }
+@global_type_table = constant [1 x %struct.MunTypeInfo*] [%struct.MunTypeInfo* @"type_info::<core::u64>"]
+

crates/mun_codegen/src/test.rs

@@ -7,6 +7,29 @@ use mun_target::spec::Target;
 use std::cell::RefCell;
 use std::sync::Arc;
 
+#[test]
+fn issue_228_never_if() {
+    test_snapshot(
+        r#"
+    pub  fn fact(n: usize) -> usize {
+   	    if n == 0 {return 1} else {return n * (n-1)}
+   	    return 2;
+    }
+    "#,
+    )
+}
+
+#[test]
+fn issue_228() {
+    test_snapshot(
+        r#"
+    pub  fn fact(n: usize) -> usize {
+   	    if n == 0 {return 1} else {n * (n-1)}
+    }
+    "#,
+    )
+}
+
 #[test]
 fn issue_128() {
     test_snapshot(