Commit fd1284ebd07ded1c67bbaff4c14f093051e56f59 | zig

author	John Schmidt <john.schmidt.h@gmail.com> 2022-02-06 22:11:41+01:00
committer	Andrew Kelley <andrew@ziglang.org> 2022-02-06 21:26:26-05:00
log	fd1284ebd07ded1c67bbaff4c14f093051e56f59
tree	3ceb66a3288aae5aa8495ff00e7af89c9561f134
parent	adc9a282d8b3cbe58e07c965fe40fb1dd8666bd7

stage2: apply type coercion in if expressions

When setting the break value in an if expression we must explicitly
check if a result location type coercion that needs to happen. This was
already done for switch expression, so let's just imitate that check
and fix for if expressions. To make this possible, we now also propagate
`rl_ty_inst` to sub scopes.

2 files changed, 40 insertions(+), 8 deletions(-)

src
- AstGen.zig
test
- behavior
  - basic.zig

src/AstGen.zig+34-8

 @@ -5118,8 +5118,10 @@ fn setCondBrPayloadElideBlockStorePtr(
     const astgen = then_scope.astgen;
     const then_body = then_scope.instructionsSliceUpto(else_scope);
     const else_body = else_scope.instructionsSlice();
-    const then_body_len = @intCast(u32, then_body.len + @boolToInt(then_break != 0));
+    const has_then_break = then_break != 0;
-    const else_body_len = @intCast(u32, else_body.len + @boolToInt(else_break != 0));
+    const has_else_break = else_break != 0;
+    const then_body_len = @intCast(u32, then_body.len + @boolToInt(has_then_break));
+    const else_body_len = @intCast(u32, else_body.len + @boolToInt(has_else_break));
     try astgen.extra.ensureUnusedCapacity(astgen.gpa, @typeInfo(Zir.Inst.CondBr).Struct.fields.len +
         then_body_len + else_body_len);
 @@ -5135,26 +5137,49 @@ fn setCondBrPayloadElideBlockStorePtr(
     const then_body_len_index = condbr_pl + 1;
     const else_body_len_index = condbr_pl + 2;
+    // The break instructions need to have their operands coerced if the
+    // switch's result location is a `ty`. In this case we overwrite the
+    // `store_to_block_ptr` instruction with an `as` instruction and repurpose
+    // it as the break operand.
     for (then_body) |src_inst| {
-        if (zir_tags[src_inst] == .store_to_block_ptr) {
+        if (zir_tags[src_inst] == .store_to_block_ptr and
-            if (zir_datas[src_inst].bin.lhs == block_ptr) {
+            zir_datas[src_inst].bin.lhs == block_ptr)
+        {
+            if (then_scope.rl_ty_inst != .none and has_then_break) {
+                zir_tags[src_inst] = .as;
+                zir_datas[src_inst].bin = .{
+                    .lhs = then_scope.rl_ty_inst,
+                    .rhs = zir_datas[then_break].@"break".operand,
+                };
+                zir_datas[then_break].@"break".operand = indexToRef(src_inst);
+            } else {
                 astgen.extra.items[then_body_len_index] -= 1;
                 continue;
             }
         }
         astgen.extra.appendAssumeCapacity(src_inst);
     }
-    if (then_break != 0) astgen.extra.appendAssumeCapacity(then_break);
+    if (has_then_break) astgen.extra.appendAssumeCapacity(then_break);
     for (else_body) |src_inst| {
-        if (zir_tags[src_inst] == .store_to_block_ptr) {
+        if (zir_tags[src_inst] == .store_to_block_ptr and
-            if (zir_datas[src_inst].bin.lhs == block_ptr) {
+            zir_datas[src_inst].bin.lhs == block_ptr)
+        {
+            if (else_scope.rl_ty_inst != .none and has_else_break) {
+                zir_tags[src_inst] = .as;
+                zir_datas[src_inst].bin = .{
+                    .lhs = else_scope.rl_ty_inst,
+                    .rhs = zir_datas[else_break].@"break".operand,
+                };
+                zir_datas[else_break].@"break".operand = indexToRef(src_inst);
+            } else {
                 astgen.extra.items[else_body_len_index] -= 1;
                 continue;
             }
         }
         astgen.extra.appendAssumeCapacity(src_inst);
     }
-    if (else_break != 0) astgen.extra.appendAssumeCapacity(else_break);
+    if (has_else_break) astgen.extra.appendAssumeCapacity(else_break);
 }
 fn whileExpr(
 @@ -9460,6 +9485,7 @@ const GenZir = struct {
             .decl_node_index = gz.decl_node_index,
             .decl_line = gz.decl_line,
             .parent = scope,
+            .rl_ty_inst = gz.rl_ty_inst,
             .astgen = gz.astgen,
             .suspend_node = gz.suspend_node,
             .nosuspend_node = gz.nosuspend_node,

test/behavior/basic.zig+6

...	@@ -693,3 +693,9 @@ test "variable name containing underscores does not shadow int primitive" {	...	@@ -693,3 +693,9 @@ test "variable name containing underscores does not shadow int primitive" {
693	_ = u6__4;	693	_ = u6__4;
694	_ = i2_04_8;	694	_ = i2_04_8;
695	}	695	}
		696
		697	test "if expression type coercion" {
		698	var cond: bool = true;
		699	const x: u16 = if (cond) 1 else 0;
		700	try expect(@as(u16, x) == 1);
		701	}