Merge pull request #12796 from Vexu/referenced-by-v2

stage2: add referenced by trace to compile errors attempt #2 (+ some fixes)

test/cases/compile_errors/comptime_continue_to_outer_inline_loop.zig

@@ -0,0 +1,21 @@
+pub export fn entry() void {
+    var a = false;
+    const arr1 = .{ 1, 2, 3 };
+    loop: inline for (arr1) |val1| {
+        _ = val1;
+        if (a) {
+            const arr = .{ 1, 2, 3 };
+            inline for (arr) |val| {
+                if (val < 3) continue :loop;
+                if (val != 3) unreachable;
+            }
+        }
+    }
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :9:30: error: comptime control flow inside runtime block
+// :6:13: note: runtime control flow here

test/cases/compile_errors/comptime_store_in_comptime_switch_in_runtime_if.zig

@@ -0,0 +1,25 @@
+fn foo() bool {
+    return false;
+}
+
+pub export fn entry() void {
+    const Widget = union(enum) { a: u0 };
+
+    comptime var a = 1;
+    const info = @typeInfo(Widget).Union;
+    inline for (info.fields) |field| {
+        if (foo()) {
+            switch (field.field_type) {
+                u0 => a = 2,
+                else => unreachable,
+            }
+        }
+    }
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :13:27: error: store to comptime variable depends on runtime condition
+// :11:16: note: runtime condition here

test/cases/compile_errors/top_level_decl_dependency_loop.zig

@@ -10,4 +10,3 @@ export fn entry() void {
 // target=native
 //
 // :1:1: error: dependency loop detected
-// :2:19: note: referenced here