Auto merge of #12840 - tesuji:const-asserts, r=llogiq

Don't lint `assertions_on_constants` on any const assertions

close #12816
close #12847
cc #12817

----

changelog: Fix false positives in consts for `assertions_on_constants` and `unnecessary_operation`.

clippy_lints/src/assertions_on_constants.rs

@@ -1,7 +1,8 @@
-use clippy_utils::consts::{constant_with_source, Constant, ConstantSource};
+use clippy_utils::consts::{constant, Constant};
 use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::is_inside_always_const_context;
 use clippy_utils::macros::{find_assert_args, root_macro_call_first_node, PanicExpn};
-use rustc_hir::{Expr, Item, ItemKind, Node};
+use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::sym;
@@ -42,17 +43,16 @@ impl<'tcx> LateLintPass<'tcx> for AssertionsOnConstants {
         let Some((condition, panic_expn)) = find_assert_args(cx, e, macro_call.expn) else {
             return;
         };
-        let Some((Constant::Bool(val), source)) = constant_with_source(cx, cx.typeck_results(), condition) else {
+        let Some(Constant::Bool(val)) = constant(cx, cx.typeck_results(), condition) else {
             return;
         };
-        if let ConstantSource::Constant = source
-            && let Node::Item(Item {
-                kind: ItemKind::Const(..),
-                ..
-            }) = cx.tcx.parent_hir_node(e.hir_id)
-        {
-            return;
+
+        match condition.kind {
+            ExprKind::Path(..) | ExprKind::Lit(_) => {},
+            _ if is_inside_always_const_context(cx.tcx, e.hir_id) => return,
+            _ => {},
         }
+
         if val {
             span_lint_and_help(
                 cx,

clippy_lints/src/default_numeric_fallback.rs

@@ -50,6 +50,8 @@ declare_lint_pass!(DefaultNumericFallback => [DEFAULT_NUMERIC_FALLBACK]);
 impl<'tcx> LateLintPass<'tcx> for DefaultNumericFallback {
     fn check_body(&mut self, cx: &LateContext<'tcx>, body: &Body<'tcx>) {
         let hir = cx.tcx.hir();
+        // NOTE: this is different from `clippy_utils::is_inside_always_const_context`.
+        // Inline const supports type inference.
         let is_parent_const = matches!(
             hir.body_const_context(hir.body_owner_def_id(body.id())),
             Some(ConstContext::Const { inline: false } | ConstContext::Static(_))

clippy_lints/src/no_effect.rs

@@ -1,7 +1,9 @@
 use clippy_utils::diagnostics::{span_lint_hir, span_lint_hir_and_then};
 use clippy_utils::source::snippet_opt;
 use clippy_utils::ty::has_drop;
-use clippy_utils::{any_parent_is_automatically_derived, is_lint_allowed, path_to_local, peel_blocks};
+use clippy_utils::{
+    any_parent_is_automatically_derived, is_inside_always_const_context, is_lint_allowed, path_to_local, peel_blocks,
+};
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{
@@ -258,13 +260,16 @@ fn has_no_effect(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
 
 fn check_unnecessary_operation(cx: &LateContext<'_>, stmt: &Stmt<'_>) {
     if let StmtKind::Semi(expr) = stmt.kind
+        && !in_external_macro(cx.sess(), stmt.span)
         && let ctxt = stmt.span.ctxt()
         && expr.span.ctxt() == ctxt
         && let Some(reduced) = reduce_expression(cx, expr)
-        && !in_external_macro(cx.sess(), stmt.span)
         && reduced.iter().all(|e| e.span.ctxt() == ctxt)
     {
         if let ExprKind::Index(..) = &expr.kind {
+            if is_inside_always_const_context(cx.tcx, expr.hir_id) {
+                return;
+            }
             let snippet =
                 if let (Some(arr), Some(func)) = (snippet_opt(cx, reduced[0].span), snippet_opt(cx, reduced[1].span)) {
                     format!("assert!({}.len() > {});", &arr, &func)