Auto merge of rust-lang#7068 - boxdot:remove-std-ptr-null, r=camsteffen

Remove paths::STD_PTR_NULL

Related to rust-lang#5393

changelog: none

Author: bors

clippy_lints/src/transmuting_null.rs

@@ -1,6 +1,6 @@
 use crate::consts::{constant_context, Constant};
 use clippy_utils::diagnostics::span_lint;
-use clippy_utils::{match_qpath, paths};
+use clippy_utils::{match_def_path, paths};
 use if_chain::if_chain;
 use rustc_ast::LitKind;
 use rustc_hir::{Expr, ExprKind};
@@ -38,10 +38,10 @@ impl<'tcx> LateLintPass<'tcx> for TransmutingNull {
 
         if_chain! {
             if let ExprKind::Call(func, args) = expr.kind;
-            if let ExprKind::Path(ref path) = func.kind;
-            if match_qpath(path, &paths::STD_MEM_TRANSMUTE);
             if args.len() == 1;
-
+            if let ExprKind::Path(ref path) = func.kind;
+            if let Some(func_def_id) = cx.qpath_res(path, func.hir_id).opt_def_id();
+            if match_def_path(cx, func_def_id, &paths::TRANSMUTE);
             then {
 
                 // Catching transmute over constants that resolve to `null`.
@@ -69,10 +69,10 @@ impl<'tcx> LateLintPass<'tcx> for TransmutingNull {
                 // Catching:
                 // `std::mem::transmute(std::ptr::null::<i32>())`
                 if_chain! {
-                    if let ExprKind::Call(func1, args1) = args[0].kind;
+                    if let ExprKind::Call(func1, []) = args[0].kind;
                     if let ExprKind::Path(ref path1) = func1.kind;
-                    if match_qpath(path1, &paths::STD_PTR_NULL);
-                    if args1.is_empty();
+                    if let Some(func1_def_id) = cx.qpath_res(path1, func1.hir_id).opt_def_id();
+                    if match_def_path(cx, func1_def_id, &paths::PTR_NULL);
                     then {
                         span_lint(cx, TRANSMUTING_NULL, expr.span, LINT_MSG)
                     }

clippy_utils/src/paths.rs

@@ -142,8 +142,6 @@ pub const STDERR: [&str; 4] = ["std", "io", "stdio", "stderr"];
 pub const STDOUT: [&str; 4] = ["std", "io", "stdio", "stdout"];
 pub const STD_CONVERT_IDENTITY: [&str; 3] = ["std", "convert", "identity"];
 pub const STD_FS_CREATE_DIR: [&str; 3] = ["std", "fs", "create_dir"];
-pub const STD_MEM_TRANSMUTE: [&str; 3] = ["std", "mem", "transmute"];
-pub const STD_PTR_NULL: [&str; 3] = ["std", "ptr", "null"];
 pub const STRING_AS_MUT_STR: [&str; 4] = ["alloc", "string", "String", "as_mut_str"];
 pub const STRING_AS_STR: [&str; 4] = ["alloc", "string", "String", "as_str"];
 pub const STR_ENDS_WITH: [&str; 4] = ["core", "str", "<impl str>", "ends_with"];