zig

commit 23837094312763ffe6e598df80fdc2ef63f73ab5 (tree)
parent 43d5bea7af8933723a457da45714b144d95e2c70
Author: pentuppup <pentuppup@noreply.codeberg.org>
Date:   Tue, 17 Feb 2026 13:38:00 -0500

coerce assembly clobbers in sema

Diffstat:
M
src/Sema.zig
 | 
10
+++++++---
M
src/Zcu.zig
 | 
8
++++++++
A
test/cases/compile_errors/undefined_assembly_clobbers.zig
 | 
7
+++++++

3 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/src/Sema.zig b/src/Sema.zig
@@ -15649,11 +15649,15 @@ fn zirAsm(
         inputs[arg_i] = .{ .c = constraint, .n = name };
     }
 
+    const clobbers_src = block.src(.{ .asm_clobbers = src.offset.node_offset.x });
+    const clobbers_ty = try sema.getBuiltinType(src, .@"assembly.Clobbers");
     const clobbers = if (extra.data.clobbers == .none) empty: {
-        const clobbers_ty = try sema.getBuiltinType(src, .@"assembly.Clobbers");
         break :empty try sema.structInitEmpty(block, clobbers_ty, src, src);
-    } else sema.resolveInst(extra.data.clobbers); // Already coerced by AstGen.
-    const clobbers_val = try sema.resolveConstDefinedValue(block, src, clobbers, .{ .simple = .clobber });
+    } else clobbers: {
+        const uncoerced = sema.resolveInst(extra.data.clobbers);
+        break :clobbers try sema.coerce(block, clobbers_ty, uncoerced, clobbers_src);
+    };
+    const clobbers_val = try sema.resolveConstDefinedValue(block, clobbers_src, clobbers, .{ .simple = .clobber });
     needed_capacity += asm_source.len / 4 + 1;
 
     try sema.air_extra.ensureUnusedCapacity(gpa, needed_capacity);
diff --git a/src/Zcu.zig b/src/Zcu.zig
@@ -1602,6 +1602,12 @@ pub const SrcLoc = struct {
                     // token points to the ')'
                     tree.tokenToSpan(data[1] - 1);
             },
+            .asm_clobbers => |offset| {
+                const tree = try src_loc.file_scope.getTree(zcu);
+                const node = offset.toAbsolute(src_loc.base_node);
+                const full = tree.fullAsm(node).?;
+                return tree.nodeToSpan(full.ast.clobbers.unwrap().?); // this should only be reachable if the clobbers are written in the source
+            },
             .for_input => |for_input| {
                 const tree = try src_loc.file_scope.getTree(zcu);
                 const node = for_input.for_node_offset.toAbsolute(src_loc.base_node);
@@ -2552,6 +2558,8 @@ pub const LazySrcLoc = struct {
             offset: Ast.Node.Offset,
             output_index: u32,
         },
+        /// Points to the assembly node
+        asm_clobbers: Ast.Node.Offset,
         /// The source location points to a for loop input.
         for_input: struct {
             /// Points to the for loop AST node.
diff --git a/test/cases/compile_errors/undefined_assembly_clobbers.zig b/test/cases/compile_errors/undefined_assembly_clobbers.zig
@@ -0,0 +1,7 @@
+export fn foo() void {
+    asm volatile("" ::: undefined);
+}
+
+// error
+//
+// :2:25: error: use of undefined value here causes illegal behavior