Rollup merge of rust-lang#102578 - lukas-code:ilog-panic, r=m-ou-se

Panic for invalid arguments of `{integer primitive}::ilog{,2,10}` in all modes

Decision made in rust-lang#100422 (comment)

resolves rust-lang#100422

tracking issue: rust-lang#70887

r? `@m-ou-se`

Author: Dylan-DPC

library/core/src/num/int_macros.rs

@@ -2279,9 +2279,8 @@ macro_rules! int_impl {
         ///
         /// # Panics
         ///
-        /// When the number is negative, zero, or if the base is not at least 2; it
-        /// panics in debug mode and the return value is 0 in release
-        /// mode.
+        /// This function will panic if `self` is less than or equal to zero,
+        /// or if `base` is less then 2.
         ///
         /// # Examples
         ///
@@ -2294,27 +2293,16 @@ macro_rules! int_impl {
                       without modifying the original"]
         #[inline]
         #[track_caller]
-        #[rustc_inherit_overflow_checks]
-        #[allow(arithmetic_overflow)]
         pub const fn ilog(self, base: Self) -> u32 {
-            match self.checked_ilog(base) {
-                Some(n) => n,
-                None => {
-                    // In debug builds, trigger a panic on None.
-                    // This should optimize completely out in release builds.
-                    let _ = Self::MAX + 1;
-
-                    0
-                },
-            }
+            assert!(base >= 2, "base of integer logarithm must be at least 2");
+            self.checked_ilog(base).expect("argument of integer logarithm must be positive")
         }
 
         /// Returns the base 2 logarithm of the number, rounded down.
         ///
         /// # Panics
         ///
-        /// When the number is negative or zero it panics in debug mode and the return value
-        /// is 0 in release mode.
+        /// This function will panic if `self` is less than or equal to zero.
         ///
         /// # Examples
         ///
@@ -2327,27 +2315,15 @@ macro_rules! int_impl {
                       without modifying the original"]
         #[inline]
         #[track_caller]
-        #[rustc_inherit_overflow_checks]
-        #[allow(arithmetic_overflow)]
         pub const fn ilog2(self) -> u32 {
-            match self.checked_ilog2() {
-                Some(n) => n,
-                None => {
-                    // In debug builds, trigger a panic on None.
-                    // This should optimize completely out in release builds.
-                    let _ = Self::MAX + 1;
-
-                    0
-                },
-            }
+            self.checked_ilog2().expect("argument of integer logarithm must be positive")
         }
 
         /// Returns the base 10 logarithm of the number, rounded down.
         ///
         /// # Panics
         ///
-        /// When the number is negative or zero it panics in debug mode and the return value
-        /// is 0 in release mode.
+        /// This function will panic if `self` is less than or equal to zero.
         ///
         /// # Example
         ///
@@ -2360,19 +2336,8 @@ macro_rules! int_impl {
                       without modifying the original"]
         #[inline]
         #[track_caller]
-        #[rustc_inherit_overflow_checks]
-        #[allow(arithmetic_overflow)]
         pub const fn ilog10(self) -> u32 {
-            match self.checked_ilog10() {
-                Some(n) => n,
-                None => {
-                    // In debug builds, trigger a panic on None.
-                    // This should optimize completely out in release builds.
-                    let _ = Self::MAX + 1;
-
-                    0
-                },
-            }
+            self.checked_ilog10().expect("argument of integer logarithm must be positive")
         }
 
         /// Returns the logarithm of the number with respect to an arbitrary base,

library/core/src/num/uint_macros.rs

@@ -692,8 +692,7 @@ macro_rules! uint_impl {
         ///
         /// # Panics
         ///
-        /// When the number is zero, or if the base is not at least 2;
-        /// it panics in debug mode and the return value is 0 in release mode.
+        /// This function will panic if `self` is zero, or if `base` is less then 2.
         ///
         /// # Examples
         ///
@@ -706,27 +705,16 @@ macro_rules! uint_impl {
                       without modifying the original"]
         #[inline]
         #[track_caller]
-        #[rustc_inherit_overflow_checks]
-        #[allow(arithmetic_overflow)]
         pub const fn ilog(self, base: Self) -> u32 {
-            match self.checked_ilog(base) {
-                Some(n) => n,
-                None => {
-                    // In debug builds, trigger a panic on None.
-                    // This should optimize completely out in release builds.
-                    let _ = Self::MAX + 1;
-
-                    0
-                },
-            }
+            assert!(base >= 2, "base of integer logarithm must be at least 2");
+            self.checked_ilog(base).expect("argument of integer logarithm must be positive")
         }
 
         /// Returns the base 2 logarithm of the number, rounded down.
         ///
         /// # Panics
         ///
-        /// When the number is zero it panics in debug mode and
-        /// the return value is 0 in release mode.
+        /// This function will panic if `self` is zero.
         ///
         /// # Examples
         ///
@@ -739,27 +727,15 @@ macro_rules! uint_impl {
                       without modifying the original"]
         #[inline]
         #[track_caller]
-        #[rustc_inherit_overflow_checks]
-        #[allow(arithmetic_overflow)]
         pub const fn ilog2(self) -> u32 {
-            match self.checked_ilog2() {
-                Some(n) => n,
-                None => {
-                    // In debug builds, trigger a panic on None.
-                    // This should optimize completely out in release builds.
-                    let _ = Self::MAX + 1;
-
-                    0
-                },
-            }
+            self.checked_ilog2().expect("argument of integer logarithm must be positive")
         }
 
         /// Returns the base 10 logarithm of the number, rounded down.
         ///
         /// # Panics
         ///
-        /// When the number is zero it panics in debug mode and the
-        /// return value is 0 in release mode.
+        /// This function will panic if `self` is zero.
         ///
         /// # Example
         ///
@@ -772,19 +748,8 @@ macro_rules! uint_impl {
                       without modifying the original"]
         #[inline]
         #[track_caller]
-        #[rustc_inherit_overflow_checks]
-        #[allow(arithmetic_overflow)]
         pub const fn ilog10(self) -> u32 {
-            match self.checked_ilog10() {
-                Some(n) => n,
-                None => {
-                    // In debug builds, trigger a panic on None.
-                    // This should optimize completely out in release builds.
-                    let _ = Self::MAX + 1;
-
-                    0
-                },
-            }
+            self.checked_ilog10().expect("argument of integer logarithm must be positive")
         }
 
         /// Returns the logarithm of the number with respect to an arbitrary base,

library/core/tests/num/int_log.rs

@@ -164,3 +164,33 @@ fn ilog10_u64() {
 fn ilog10_u128() {
     ilog10_loop! { u128, 38 }
 }
+
+#[test]
+#[should_panic(expected = "argument of integer logarithm must be positive")]
+fn ilog2_of_0_panic() {
+    let _ = 0u32.ilog2();
+}
+
+#[test]
+#[should_panic(expected = "argument of integer logarithm must be positive")]
+fn ilog10_of_0_panic() {
+    let _ = 0u32.ilog10();
+}
+
+#[test]
+#[should_panic(expected = "argument of integer logarithm must be positive")]
+fn ilog3_of_0_panic() {
+    let _ = 0u32.ilog(3);
+}
+
+#[test]
+#[should_panic(expected = "base of integer logarithm must be at least 2")]
+fn ilog0_of_1_panic() {
+    let _ = 1u32.ilog(0);
+}
+
+#[test]
+#[should_panic(expected = "base of integer logarithm must be at least 2")]
+fn ilog1_of_1_panic() {
+    let _ = 1u32.ilog(1);
+}