Auto merge of #7629 - mikerite:fix-7623-2, r=xFrednet

Make `approx_const` MSRV aware changelog: [`approx_const`]: Add MRSV checks for LOG10_2 and LOG2_10. Fixes #7623
rust-lang · Sep 5, 2021 · e5ae3f5 · e5ae3f5
2 parents a8c269a + 19d8a3e
commit e5ae3f5
Show file tree

Hide file tree

Showing 8 changed files with 145 additions and 82 deletions.
diff --git a/clippy_lints/src/approx_const.rs b/clippy_lints/src/approx_const.rs
@@ -1,8 +1,10 @@
-use clippy_utils::diagnostics::span_lint;
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::{meets_msrv, msrvs};
 use rustc_ast::ast::{FloatTy, LitFloatType, LitKind};
 use rustc_hir::{Expr, ExprKind};
-use rustc_lint::{LateContext, LateLintPass};
-use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_semver::RustcVersion;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::symbol;
 use std::f64::consts as f64;
 
@@ -36,68 +38,81 @@ declare_clippy_lint! {
     "the approximate of a known float constant (in `std::fXX::consts`)"
 }
 
-// Tuples are of the form (constant, name, min_digits)
-const KNOWN_CONSTS: [(f64, &str, usize); 18] = [
-    (f64::E, "E", 4),
-    (f64::FRAC_1_PI, "FRAC_1_PI", 4),
-    (f64::FRAC_1_SQRT_2, "FRAC_1_SQRT_2", 5),
-    (f64::FRAC_2_PI, "FRAC_2_PI", 5),
-    (f64::FRAC_2_SQRT_PI, "FRAC_2_SQRT_PI", 5),
-    (f64::FRAC_PI_2, "FRAC_PI_2", 5),
-    (f64::FRAC_PI_3, "FRAC_PI_3", 5),
-    (f64::FRAC_PI_4, "FRAC_PI_4", 5),
-    (f64::FRAC_PI_6, "FRAC_PI_6", 5),
-    (f64::FRAC_PI_8, "FRAC_PI_8", 5),
-    (f64::LN_10, "LN_10", 5),
-    (f64::LN_2, "LN_2", 5),
-    (f64::LOG10_E, "LOG10_E", 5),
-    (f64::LOG2_E, "LOG2_E", 5),
-    (f64::LOG2_10, "LOG2_10", 5),
-    (f64::LOG10_2, "LOG10_2", 5),
-    (f64::PI, "PI", 3),
-    (f64::SQRT_2, "SQRT_2", 5),
+// Tuples are of the form (constant, name, min_digits, msrv)
+const KNOWN_CONSTS: [(f64, &str, usize, Option<RustcVersion>); 18] = [
+    (f64::E, "E", 4, None),
+    (f64::FRAC_1_PI, "FRAC_1_PI", 4, None),
+    (f64::FRAC_1_SQRT_2, "FRAC_1_SQRT_2", 5, None),
+    (f64::FRAC_2_PI, "FRAC_2_PI", 5, None),
+    (f64::FRAC_2_SQRT_PI, "FRAC_2_SQRT_PI", 5, None),
+    (f64::FRAC_PI_2, "FRAC_PI_2", 5, None),
+    (f64::FRAC_PI_3, "FRAC_PI_3", 5, None),
+    (f64::FRAC_PI_4, "FRAC_PI_4", 5, None),
+    (f64::FRAC_PI_6, "FRAC_PI_6", 5, None),
+    (f64::FRAC_PI_8, "FRAC_PI_8", 5, None),
+    (f64::LN_2, "LN_2", 5, None),
+    (f64::LN_10, "LN_10", 5, None),
+    (f64::LOG2_10, "LOG2_10", 5, Some(msrvs::LOG2_10)),
+    (f64::LOG2_E, "LOG2_E", 5, None),
+    (f64::LOG10_2, "LOG10_2", 5, Some(msrvs::LOG10_2)),
+    (f64::LOG10_E, "LOG10_E", 5, None),
+    (f64::PI, "PI", 3, None),
+    (f64::SQRT_2, "SQRT_2", 5, None),
 ];
 
-declare_lint_pass!(ApproxConstant => [APPROX_CONSTANT]);
+pub struct ApproxConstant {
+    msrv: Option<RustcVersion>,
+}
 
-impl<'tcx> LateLintPass<'tcx> for ApproxConstant {
-    fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
-        if let ExprKind::Lit(lit) = &e.kind {
-            check_lit(cx, &lit.node, e);
+impl ApproxConstant {
+    #[must_use]
+    pub fn new(msrv: Option<RustcVersion>) -> Self {
+        Self { msrv }
+    }
+
+    fn check_lit(&self, cx: &LateContext<'_>, lit: &LitKind, e: &Expr<'_>) {
+        match *lit {
+            LitKind::Float(s, LitFloatType::Suffixed(fty)) => match fty {
+                FloatTy::F32 => self.check_known_consts(cx, e, s, "f32"),
+                FloatTy::F64 => self.check_known_consts(cx, e, s, "f64"),
+            },
+            LitKind::Float(s, LitFloatType::Unsuffixed) => self.check_known_consts(cx, e, s, "f{32, 64}"),
+            _ => (),
         }
     }
-}
 
-fn check_lit(cx: &LateContext<'_>, lit: &LitKind, e: &Expr<'_>) {
-    match *lit {
-        LitKind::Float(s, LitFloatType::Suffixed(fty)) => match fty {
-            FloatTy::F32 => check_known_consts(cx, e, s, "f32"),
-            FloatTy::F64 => check_known_consts(cx, e, s, "f64"),
-        },
-        LitKind::Float(s, LitFloatType::Unsuffixed) => check_known_consts(cx, e, s, "f{32, 64}"),
-        _ => (),
+    fn check_known_consts(&self, cx: &LateContext<'_>, e: &Expr<'_>, s: symbol::Symbol, module: &str) {
+        let s = s.as_str();
+        if s.parse::<f64>().is_ok() {
+            for &(constant, name, min_digits, msrv) in &KNOWN_CONSTS {
+                if is_approx_const(constant, &s, min_digits)
+                    && msrv.as_ref().map_or(true, |msrv| meets_msrv(self.msrv.as_ref(), msrv))
+                {
+                    span_lint_and_help(
+                        cx,
+                        APPROX_CONSTANT,
+                        e.span,
+                        &format!("approximate value of `{}::consts::{}` found", module, &name),
+                        None,
+                        "consider using the constant directly",
+                    );
+                    return;
+                }
+            }
+        }
     }
 }
 
-fn check_known_consts(cx: &LateContext<'_>, e: &Expr<'_>, s: symbol::Symbol, module: &str) {
-    let s = s.as_str();
-    if s.parse::<f64>().is_ok() {
-        for &(constant, name, min_digits) in &KNOWN_CONSTS {
-            if is_approx_const(constant, &s, min_digits) {
-                span_lint(
-                    cx,
-                    APPROX_CONSTANT,
-                    e.span,
-                    &format!(
-                        "approximate value of `{}::consts::{}` found. \
-                         Consider using it directly",
-                        module, &name
-                    ),
-                );
-                return;
-            }
+impl_lint_pass!(ApproxConstant => [APPROX_CONSTANT]);
+
+impl<'tcx> LateLintPass<'tcx> for ApproxConstant {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
+        if let ExprKind::Lit(lit) = &e.kind {
+            self.check_lit(cx, &lit.node, e);
         }
     }
+
+    extract_msrv_attr!(LateContext);
 }
 
 /// Returns `false` if the number of significant figures in `value` are

diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
@@ -1869,7 +1869,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(needless_bool::NeedlessBool));
     store.register_late_pass(|| Box::new(needless_bool::BoolComparison));
     store.register_late_pass(|| Box::new(needless_for_each::NeedlessForEach));
-    store.register_late_pass(|| Box::new(approx_const::ApproxConstant));
     store.register_late_pass(|| Box::new(misc::MiscLints));
     store.register_late_pass(|| Box::new(eta_reduction::EtaReduction));
     store.register_late_pass(|| Box::new(identity_op::IdentityOp));
@@ -1898,6 +1897,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     });
 
     let avoid_breaking_exported_api = conf.avoid_breaking_exported_api;
+    store.register_late_pass(move || Box::new(approx_const::ApproxConstant::new(msrv)));
     store.register_late_pass(move || Box::new(methods::Methods::new(avoid_breaking_exported_api, msrv)));
     store.register_late_pass(move || Box::new(matches::Matches::new(msrv)));
     store.register_early_pass(move || Box::new(manual_non_exhaustive::ManualNonExhaustive::new(msrv)));

diff --git a/clippy_lints/src/utils/conf.rs b/clippy_lints/src/utils/conf.rs
@@ -132,7 +132,7 @@ define_Conf! {
     ///
     /// Suppress lints whenever the suggested change would cause breakage for other crates.
     (avoid_breaking_exported_api: bool = true),
-    /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE.
+    /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT.
     ///
     /// The minimum rust version that the project supports
     (msrv: Option<String> = None),

diff --git a/clippy_utils/src/msrvs.rs b/clippy_utils/src/msrvs.rs
@@ -17,6 +17,7 @@ msrv_aliases! {
     1,50,0 { BOOL_THEN }
     1,46,0 { CONST_IF_MATCH }
     1,45,0 { STR_STRIP_PREFIX }
+    1,43,0 { LOG2_10, LOG10_2 }
     1,42,0 { MATCHES_MACRO }
     1,41,0 { RE_REBALANCING_COHERENCE, RESULT_MAP_OR_ELSE }
     1,40,0 { MEM_TAKE, NON_EXHAUSTIVE, OPTION_AS_DEREF }

diff --git a/tests/ui/approx_const.stderr b/tests/ui/approx_const.stderr
@@ -1,130 +1,171 @@
-error: approximate value of `f{32, 64}::consts::E` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::E` found
   --> $DIR/approx_const.rs:4:16
    |
 LL |     let my_e = 2.7182;
    |                ^^^^^^
    |
    = note: `-D clippy::approx-constant` implied by `-D warnings`
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::E` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::E` found
   --> $DIR/approx_const.rs:5:20
    |
 LL |     let almost_e = 2.718;
    |                    ^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_1_PI` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_1_PI` found
   --> $DIR/approx_const.rs:8:24
    |
 LL |     let my_1_frac_pi = 0.3183;
    |                        ^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_1_SQRT_2` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_1_SQRT_2` found
   --> $DIR/approx_const.rs:11:28
    |
 LL |     let my_frac_1_sqrt_2 = 0.70710678;
    |                            ^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_1_SQRT_2` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_1_SQRT_2` found
   --> $DIR/approx_const.rs:12:32
    |
 LL |     let almost_frac_1_sqrt_2 = 0.70711;
    |                                ^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_2_PI` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_2_PI` found
   --> $DIR/approx_const.rs:15:24
    |
 LL |     let my_frac_2_pi = 0.63661977;
    |                        ^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_2_SQRT_PI` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_2_SQRT_PI` found
   --> $DIR/approx_const.rs:18:27
    |
 LL |     let my_frac_2_sq_pi = 1.128379;
    |                           ^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_PI_2` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_PI_2` found
   --> $DIR/approx_const.rs:21:24
    |
 LL |     let my_frac_pi_2 = 1.57079632679;
    |                        ^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_PI_3` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_PI_3` found
   --> $DIR/approx_const.rs:24:24
    |
 LL |     let my_frac_pi_3 = 1.04719755119;
    |                        ^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_PI_4` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_PI_4` found
   --> $DIR/approx_const.rs:27:24
    |
 LL |     let my_frac_pi_4 = 0.785398163397;
    |                        ^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_PI_6` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_PI_6` found
   --> $DIR/approx_const.rs:30:24
    |
 LL |     let my_frac_pi_6 = 0.523598775598;
    |                        ^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::FRAC_PI_8` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::FRAC_PI_8` found
   --> $DIR/approx_const.rs:33:24
    |
 LL |     let my_frac_pi_8 = 0.3926990816987;
    |                        ^^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::LN_10` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::LN_10` found
   --> $DIR/approx_const.rs:36:20
    |
 LL |     let my_ln_10 = 2.302585092994046;
    |                    ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::LN_2` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::LN_2` found
   --> $DIR/approx_const.rs:39:19
    |
 LL |     let my_ln_2 = 0.6931471805599453;
    |                   ^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::LOG10_E` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::LOG10_E` found
   --> $DIR/approx_const.rs:42:22
    |
 LL |     let my_log10_e = 0.4342944819032518;
    |                      ^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::LOG2_E` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::LOG2_E` found
   --> $DIR/approx_const.rs:45:21
    |
 LL |     let my_log2_e = 1.4426950408889634;
    |                     ^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::LOG2_10` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::LOG2_10` found
   --> $DIR/approx_const.rs:48:19
    |
 LL |     let log2_10 = 3.321928094887362;
    |                   ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::LOG10_2` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::LOG10_2` found
   --> $DIR/approx_const.rs:51:19
    |
 LL |     let log10_2 = 0.301029995663981;
    |                   ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::PI` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::PI` found
   --> $DIR/approx_const.rs:54:17
    |
 LL |     let my_pi = 3.1415;
    |                 ^^^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::PI` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::PI` found
   --> $DIR/approx_const.rs:55:21
    |
 LL |     let almost_pi = 3.14;
    |                     ^^^^
+   |
+   = help: consider using the constant directly
 
-error: approximate value of `f{32, 64}::consts::SQRT_2` found. Consider using it directly
+error: approximate value of `f{32, 64}::consts::SQRT_2` found
   --> $DIR/approx_const.rs:58:18
    |
 LL |     let my_sq2 = 1.4142;
    |                  ^^^^^^
+   |
+   = help: consider using the constant directly
 
 error: aborting due to 21 previous errors
 
diff --git a/tests/ui/min_rust_version_attr.rs b/tests/ui/min_rust_version_attr.rs
@@ -4,6 +4,11 @@
 
 use std::ops::{Deref, RangeFrom};
 
+fn approx_const() {
+    let log2_10 = 3.321928094887362;
+    let log10_2 = 0.301029995663981;
+}
+
 fn cloned_instead_of_copied() {
     let _ = [1].iter().cloned();
 }