Const eval changes (#15773)

First commit treats all constants containing a macro call as non-local
and renames `eval_simple` to be a little clearer.

Second commit removes `CoreConstant` and treats most of them as though
they were local. A couple of the constants like `usize::MAX` are treated
as non-local as different targets may have different values.
`const_is_empty` will now ignore non-local constants since there's no
guarantee that they are the same across all targets/features/versions.

The third commit just changes some `eval` calls to `eval_local`. Most of
these were style lints which shouldn't be assuming the value of a
constant won't ever change.

changelog: none

Author: samueltardieu

clippy_lints/src/assertions_on_constants.rs

@@ -50,7 +50,8 @@ impl<'tcx> LateLintPass<'tcx> for AssertionsOnConstants {
                 _ => return,
             }
             && let Some((condition, _)) = find_assert_args(cx, e, macro_call.expn)
-            && let Some((Constant::Bool(assert_val), const_src)) = ConstEvalCtxt::new(cx).eval_with_source(condition)
+            && let Some((Constant::Bool(assert_val), const_src)) =
+                ConstEvalCtxt::new(cx).eval_with_source(condition, macro_call.span.ctxt())
             && let in_const_context = is_inside_always_const_context(cx.tcx, e.hir_id)
             && (const_src.is_local() || !in_const_context)
             && !(is_debug && as_bool_lit(condition) == Some(false))

clippy_lints/src/enum_clike.rs

@@ -43,12 +43,8 @@ impl<'tcx> LateLintPass<'tcx> for UnportableVariant {
                 if let Some(anon_const) = &var.disr_expr {
                     let def_id = cx.tcx.hir_body_owner_def_id(anon_const.body);
                     let mut ty = cx.tcx.type_of(def_id.to_def_id()).instantiate_identity();
-                    let constant = cx
-                        .tcx
-                        .const_eval_poly(def_id.to_def_id())
-                        .ok()
-                        .map(|val| rustc_middle::mir::Const::from_value(val, ty));
-                    if let Some(Constant::Int(val)) = constant.and_then(|c| mir_to_const(cx.tcx, c)) {
+                    let constant = cx.tcx.const_eval_poly(def_id.to_def_id()).ok();
+                    if let Some(Constant::Int(val)) = constant.and_then(|c| mir_to_const(cx.tcx, c, ty)) {
                         if let ty::Adt(adt, _) = ty.kind()
                             && adt.is_enum()
                         {

clippy_lints/src/floating_point_arithmetic.rs

@@ -11,6 +11,7 @@ use rustc_hir::{BinOpKind, Expr, ExprKind, PathSegment, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::declare_lint_pass;
+use rustc_span::SyntaxContext;
 use rustc_span::source_map::Spanned;
 use std::f32::consts as f32_consts;
 use std::f64::consts as f64_consts;
@@ -110,8 +111,8 @@ declare_lint_pass!(FloatingPointArithmetic => [
 
 // Returns the specialized log method for a given base if base is constant
 // and is one of 2, 10 and e
-fn get_specialized_log_method(cx: &LateContext<'_>, base: &Expr<'_>) -> Option<&'static str> {
-    if let Some(value) = ConstEvalCtxt::new(cx).eval(base) {
+fn get_specialized_log_method(cx: &LateContext<'_>, base: &Expr<'_>, ctxt: SyntaxContext) -> Option<&'static str> {
+    if let Some(value) = ConstEvalCtxt::new(cx).eval_local(base, ctxt) {
         if F32(2.0) == value || F64(2.0) == value {
             return Some("log2");
         } else if F32(10.0) == value || F64(10.0) == value {
@@ -157,7 +158,7 @@ fn prepare_receiver_sugg<'a>(cx: &LateContext<'_>, mut expr: &'a Expr<'a>) -> Su
 }
 
 fn check_log_base(cx: &LateContext<'_>, expr: &Expr<'_>, receiver: &Expr<'_>, args: &[Expr<'_>]) {
-    if let Some(method) = get_specialized_log_method(cx, &args[0]) {
+    if let Some(method) = get_specialized_log_method(cx, &args[0], expr.span.ctxt()) {
         span_lint_and_sugg(
             cx,
             SUBOPTIMAL_FLOPS,
@@ -205,7 +206,7 @@ fn check_ln1p(cx: &LateContext<'_>, expr: &Expr<'_>, receiver: &Expr<'_>) {
 // ranges [-16777215, 16777216) for type f32 as whole number floats outside
 // this range are lossy and ambiguous.
 #[expect(clippy::cast_possible_truncation)]
-fn get_integer_from_float_constant(value: &Constant<'_>) -> Option<i32> {
+fn get_integer_from_float_constant(value: &Constant) -> Option<i32> {
     match value {
         F32(num) if num.fract() == 0.0 => {
             if (-16_777_215.0..16_777_216.0).contains(num) {
@@ -517,8 +518,8 @@ fn check_mul_add(cx: &LateContext<'_>, expr: &Expr<'_>) {
 fn is_testing_positive(cx: &LateContext<'_>, expr: &Expr<'_>, test: &Expr<'_>) -> bool {
     if let ExprKind::Binary(Spanned { node: op, .. }, left, right) = expr.kind {
         match op {
-            BinOpKind::Gt | BinOpKind::Ge => is_zero(cx, right) && eq_expr_value(cx, left, test),
-            BinOpKind::Lt | BinOpKind::Le => is_zero(cx, left) && eq_expr_value(cx, right, test),
+            BinOpKind::Gt | BinOpKind::Ge => is_zero(cx, right, expr.span.ctxt()) && eq_expr_value(cx, left, test),
+            BinOpKind::Lt | BinOpKind::Le => is_zero(cx, left, expr.span.ctxt()) && eq_expr_value(cx, right, test),
             _ => false,
         }
     } else {
@@ -530,8 +531,8 @@ fn is_testing_positive(cx: &LateContext<'_>, expr: &Expr<'_>, test: &Expr<'_>) -
 fn is_testing_negative(cx: &LateContext<'_>, expr: &Expr<'_>, test: &Expr<'_>) -> bool {
     if let ExprKind::Binary(Spanned { node: op, .. }, left, right) = expr.kind {
         match op {
-            BinOpKind::Gt | BinOpKind::Ge => is_zero(cx, left) && eq_expr_value(cx, right, test),
-            BinOpKind::Lt | BinOpKind::Le => is_zero(cx, right) && eq_expr_value(cx, left, test),
+            BinOpKind::Gt | BinOpKind::Ge => is_zero(cx, left, expr.span.ctxt()) && eq_expr_value(cx, right, test),
+            BinOpKind::Lt | BinOpKind::Le => is_zero(cx, right, expr.span.ctxt()) && eq_expr_value(cx, left, test),
             _ => false,
         }
     } else {
@@ -540,8 +541,8 @@ fn is_testing_negative(cx: &LateContext<'_>, expr: &Expr<'_>, test: &Expr<'_>) -
 }
 
 /// Returns true iff expr is some zero literal
-fn is_zero(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
-    match ConstEvalCtxt::new(cx).eval_simple(expr) {
+fn is_zero(cx: &LateContext<'_>, expr: &Expr<'_>, ctxt: SyntaxContext) -> bool {
+    match ConstEvalCtxt::new(cx).eval_local(expr, ctxt) {
         Some(Int(i)) => i == 0,
         Some(F32(f)) => f == 0.0,
         Some(F64(f)) => f == 0.0,

clippy_lints/src/if_not_else.rs

@@ -60,10 +60,14 @@ impl LateLintPass<'_> for IfNotElse {
                 ),
                 // Don't lint on `… != 0`, as these are likely to be bit tests.
                 // For example, `if foo & 0x0F00 != 0 { … } else { … }` is already in the "proper" order.
-                ExprKind::Binary(op, _, rhs) if op.node == BinOpKind::Ne && !is_zero_integer_const(cx, rhs) => (
-                    "unnecessary `!=` operation",
-                    "change to `==` and swap the blocks of the `if`/`else`",
-                ),
+                ExprKind::Binary(op, _, rhs)
+                    if op.node == BinOpKind::Ne && !is_zero_integer_const(cx, rhs, e.span.ctxt()) =>
+                {
+                    (
+                        "unnecessary `!=` operation",
+                        "change to `==` and swap the blocks of the `if`/`else`",
+                    )
+                },
                 _ => return,
             };
 

clippy_lints/src/implicit_saturating_add.rs

@@ -117,10 +117,11 @@ fn get_int_max(ty: Ty<'_>) -> Option<u128> {
 fn get_const<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) -> Option<(u128, BinOpKind, &'tcx Expr<'tcx>)> {
     if let ExprKind::Binary(op, l, r) = expr.kind {
         let ecx = ConstEvalCtxt::new(cx);
-        if let Some(Constant::Int(c)) = ecx.eval(r) {
+        let ctxt = expr.span.ctxt();
+        if let Some(Constant::Int(c)) = ecx.eval_local(r, ctxt) {
             return Some((c, op.node, l));
         }
-        if let Some(Constant::Int(c)) = ecx.eval(l) {
+        if let Some(Constant::Int(c)) = ecx.eval_local(l, ctxt) {
             return Some((c, invert_op(op.node)?, r));
         }
     }

clippy_lints/src/invalid_upcast_comparisons.rs

@@ -101,7 +101,7 @@ fn upcast_comparison_bounds_err<'tcx>(
     invert: bool,
 ) {
     if let Some((lb, ub)) = lhs_bounds
-        && let Some(norm_rhs_val) = ConstEvalCtxt::new(cx).eval_full_int(rhs)
+        && let Some(norm_rhs_val) = ConstEvalCtxt::new(cx).eval_full_int(rhs, span.ctxt())
     {
         if rel == Rel::Eq || rel == Rel::Ne {
             if norm_rhs_val < lb || norm_rhs_val > ub {

clippy_lints/src/manual_float_methods.rs

@@ -1,5 +1,5 @@
 use clippy_config::Conf;
-use clippy_utils::consts::{ConstEvalCtxt, Constant};
+use clippy_utils::consts::ConstEvalCtxt;
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::source::SpanRangeExt;
@@ -146,13 +146,14 @@ impl<'tcx> LateLintPass<'tcx> for ManualFloatMethods {
             )
             && let [first, second, const_1, const_2] = exprs
             && let ecx = ConstEvalCtxt::new(cx)
-            && let Some(const_1) = ecx.eval(const_1)
-            && let Some(const_2) = ecx.eval(const_2)
+            && let ctxt = expr.span.ctxt()
+            && let Some(const_1) = ecx.eval_local(const_1, ctxt)
+            && let Some(const_2) = ecx.eval_local(const_2, ctxt)
             && path_to_local(first).is_some_and(|f| path_to_local(second).is_some_and(|s| f == s))
             // The actual infinity check, we also allow `NEG_INFINITY` before` INFINITY` just in
             // case somebody does that for some reason
-            && (is_infinity(&const_1) && is_neg_infinity(&const_2)
-                || is_neg_infinity(&const_1) && is_infinity(&const_2))
+            && (const_1.is_pos_infinity() && const_2.is_neg_infinity()
+                || const_1.is_neg_infinity() && const_2.is_pos_infinity())
             && let Some(local_snippet) = first.span.get_source_text(cx)
         {
             let variant = match (kind.node, lhs_kind.node, rhs_kind.node) {
@@ -201,21 +202,3 @@ impl<'tcx> LateLintPass<'tcx> for ManualFloatMethods {
         }
     }
 }
-
-fn is_infinity(constant: &Constant<'_>) -> bool {
-    match constant {
-        // FIXME(f16_f128): add f16 and f128 when constants are available
-        Constant::F32(float) => *float == f32::INFINITY,
-        Constant::F64(float) => *float == f64::INFINITY,
-        _ => false,
-    }
-}
-
-fn is_neg_infinity(constant: &Constant<'_>) -> bool {
-    match constant {
-        // FIXME(f16_f128): add f16 and f128 when constants are available
-        Constant::F32(float) => *float == f32::NEG_INFINITY,
-        Constant::F64(float) => *float == f64::NEG_INFINITY,
-        _ => false,
-    }
-}

clippy_lints/src/manual_rem_euclid.rs

@@ -8,6 +8,7 @@ use rustc_errors::Applicability;
 use rustc_hir::{BinOpKind, Expr, ExprKind, Node, TyKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::impl_lint_pass;
+use rustc_span::SyntaxContext;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -58,13 +59,13 @@ impl<'tcx> LateLintPass<'tcx> for ManualRemEuclid {
             && add_lhs.span.ctxt() == ctxt
             && add_rhs.span.ctxt() == ctxt
             && !expr.span.in_external_macro(cx.sess().source_map())
-            && let Some(const1) = check_for_unsigned_int_constant(cx, rem_rhs)
-            && let Some((const2, add_other)) = check_for_either_unsigned_int_constant(cx, add_lhs, add_rhs)
+            && let Some(const1) = check_for_unsigned_int_constant(cx, ctxt, rem_rhs)
+            && let Some((const2, add_other)) = check_for_either_unsigned_int_constant(cx, ctxt, add_lhs, add_rhs)
             && let ExprKind::Binary(rem2_op, rem2_lhs, rem2_rhs) = add_other.kind
             && rem2_op.node == BinOpKind::Rem
             && const1 == const2
             && let Some(hir_id) = path_to_local(rem2_lhs)
-            && let Some(const3) = check_for_unsigned_int_constant(cx, rem2_rhs)
+            && let Some(const3) = check_for_unsigned_int_constant(cx, ctxt, rem2_rhs)
             // Also ensures the const is nonzero since zero can't be a divisor
             && const2 == const3
             && rem2_lhs.span.ctxt() == ctxt
@@ -103,16 +104,21 @@ impl<'tcx> LateLintPass<'tcx> for ManualRemEuclid {
 // constant along with the other expression unchanged if so
 fn check_for_either_unsigned_int_constant<'a>(
     cx: &'a LateContext<'_>,
+    ctxt: SyntaxContext,
     left: &'a Expr<'_>,
     right: &'a Expr<'_>,
 ) -> Option<(u128, &'a Expr<'a>)> {
-    check_for_unsigned_int_constant(cx, left)
+    check_for_unsigned_int_constant(cx, ctxt, left)
         .map(|int_const| (int_const, right))
-        .or_else(|| check_for_unsigned_int_constant(cx, right).map(|int_const| (int_const, left)))
+        .or_else(|| check_for_unsigned_int_constant(cx, ctxt, right).map(|int_const| (int_const, left)))
 }
 
-fn check_for_unsigned_int_constant<'a>(cx: &'a LateContext<'_>, expr: &'a Expr<'_>) -> Option<u128> {
-    let int_const = ConstEvalCtxt::new(cx).eval_full_int(expr)?;
+fn check_for_unsigned_int_constant<'a>(
+    cx: &'a LateContext<'_>,
+    ctxt: SyntaxContext,
+    expr: &'a Expr<'_>,
+) -> Option<u128> {
+    let int_const = ConstEvalCtxt::new(cx).eval_full_int(expr, ctxt)?;
     match int_const {
         FullInt::S(s) => s.try_into().ok(),
         FullInt::U(u) => Some(u),

clippy_lints/src/manual_rotate.rs

@@ -66,7 +66,7 @@ fn parse_shift<'tcx>(
             BinOpKind::Shr => ShiftDirection::Right,
             _ => return None,
         };
-        let const_expr = ConstEvalCtxt::new(cx).eval(r)?;
+        let const_expr = ConstEvalCtxt::new(cx).eval_local(r, expr.span.ctxt())?;
         if let Constant::Int(shift) = const_expr {
             return Some((dir, shift, l));
         }

clippy_lints/src/manual_strip.rs

@@ -16,7 +16,7 @@ use rustc_lint::{LateContext, LateLintPass, LintContext as _};
 use rustc_middle::ty;
 use rustc_session::impl_lint_pass;
 use rustc_span::source_map::Spanned;
-use rustc_span::{Symbol, sym};
+use rustc_span::{Symbol, SyntaxContext, sym};
 use std::iter;
 
 declare_clippy_lint! {
@@ -92,7 +92,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualStrip {
                 return;
             }
 
-            let (strippings, bindings) = find_stripping(cx, strip_kind, target_res, pattern, then);
+            let (strippings, bindings) = find_stripping(cx, strip_kind, target_res, pattern, then, expr.span.ctxt());
             if !strippings.is_empty() && self.msrv.meets(cx, msrvs::STR_STRIP_PREFIX) {
                 let kind_word = match strip_kind {
                     StripKind::Prefix => "prefix",
@@ -166,8 +166,8 @@ fn len_arg<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx E
 }
 
 // Returns the length of the `expr` if it's a constant string or char.
-fn constant_length(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<u128> {
-    let value = ConstEvalCtxt::new(cx).eval(expr)?;
+fn constant_length(cx: &LateContext<'_>, expr: &Expr<'_>, ctxt: SyntaxContext) -> Option<u128> {
+    let value = ConstEvalCtxt::new(cx).eval_local(expr, ctxt)?;
     match value {
         Constant::Str(value) => Some(value.len() as u128),
         Constant::Char(value) => Some(value.len_utf8() as u128),
@@ -176,13 +176,18 @@ fn constant_length(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<u128> {
 }
 
 // Tests if `expr` equals the length of the pattern.
-fn eq_pattern_length<'tcx>(cx: &LateContext<'tcx>, pattern: &Expr<'_>, expr: &'tcx Expr<'_>) -> bool {
+fn eq_pattern_length<'tcx>(
+    cx: &LateContext<'tcx>,
+    pattern: &Expr<'_>,
+    expr: &'tcx Expr<'_>,
+    ctxt: SyntaxContext,
+) -> bool {
     if let ExprKind::Lit(Spanned {
         node: LitKind::Int(n, _),
         ..
     }) = expr.kind
     {
-        constant_length(cx, pattern).is_some_and(|length| n == length)
+        constant_length(cx, pattern, ctxt).is_some_and(|length| n == length)
     } else {
         len_arg(cx, expr).is_some_and(|arg| eq_expr_value(cx, pattern, arg))
     }
@@ -215,6 +220,7 @@ fn find_stripping<'tcx>(
     target: Res,
     pattern: &'tcx Expr<'_>,
     expr: &'tcx Expr<'tcx>,
+    ctxt: SyntaxContext,
 ) -> (Vec<&'tcx Expr<'tcx>>, FxHashMap<Symbol, usize>) {
     struct StrippingFinder<'a, 'tcx> {
         cx: &'a LateContext<'tcx>,
@@ -223,6 +229,7 @@ fn find_stripping<'tcx>(
         pattern: &'tcx Expr<'tcx>,
         results: Vec<&'tcx Expr<'tcx>>,
         bindings: FxHashMap<Symbol, usize>,
+        ctxt: SyntaxContext,
     }
 
     impl<'tcx> Visitor<'tcx> for StrippingFinder<'_, 'tcx> {
@@ -236,7 +243,7 @@ fn find_stripping<'tcx>(
             {
                 match (self.strip_kind, start, end) {
                     (StripKind::Prefix, Some(start), None) => {
-                        if eq_pattern_length(self.cx, self.pattern, start) {
+                        if eq_pattern_length(self.cx, self.pattern, start, self.ctxt) {
                             self.results.push(ex);
                             return;
                         }
@@ -252,7 +259,7 @@ fn find_stripping<'tcx>(
                             && let Some(left_arg) = len_arg(self.cx, left)
                             && let ExprKind::Path(left_path) = &left_arg.kind
                             && self.cx.qpath_res(left_path, left_arg.hir_id) == self.target
-                            && eq_pattern_length(self.cx, self.pattern, right)
+                            && eq_pattern_length(self.cx, self.pattern, right, self.ctxt)
                         {
                             self.results.push(ex);
                             return;
@@ -280,6 +287,7 @@ fn find_stripping<'tcx>(
         pattern,
         results: vec![],
         bindings: FxHashMap::default(),
+        ctxt,
     };
     walk_expr(&mut finder, expr);
     (finder.results, finder.bindings)