Update upstream source from tag 'upstream/1.52.1+dfsg1'

[rustc.git] / src / tools / clippy / clippy_lints / src / dbg_macro.rs

diff --git a/src/tools/clippy/clippy_lints/src/dbg_macro.rs b/src/tools/clippy/clippy_lints/src/dbg_macro.rs
new file mode 100644 (file)
index 0000000..e513dcc
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/dbg_macro.rs
@@ -0,0 +1,65 @@
+use crate::utils::{snippet_opt, span_lint_and_help, span_lint_and_sugg};
+use rustc_ast::ast;
+use rustc_ast::tokenstream::TokenStream;
+use rustc_errors::Applicability;
+use rustc_lint::{EarlyContext, EarlyLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Span;
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for usage of dbg!() macro.
+    ///
+    /// **Why is this bad?** `dbg!` macro is intended as a debugging tool. It
+    /// should not be in version control.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust,ignore
+    /// // Bad
+    /// dbg!(true)
+    ///
+    /// // Good
+    /// true
+    /// ```
+    pub DBG_MACRO,
+    restriction,
+    "`dbg!` macro is intended as a debugging tool"
+}
+
+declare_lint_pass!(DbgMacro => [DBG_MACRO]);
+
+impl EarlyLintPass for DbgMacro {
+    fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::MacCall) {
+        if mac.path == sym!(dbg) {
+            if let Some(sugg) = tts_span(mac.args.inner_tokens()).and_then(|span| snippet_opt(cx, span)) {
+                span_lint_and_sugg(
+                    cx,
+                    DBG_MACRO,
+                    mac.span(),
+                    "`dbg!` macro is intended as a debugging tool",
+                    "ensure to avoid having uses of it in version control",
+                    sugg,
+                    Applicability::MaybeIncorrect,
+                );
+            } else {
+                span_lint_and_help(
+                    cx,
+                    DBG_MACRO,
+                    mac.span(),
+                    "`dbg!` macro is intended as a debugging tool",
+                    None,
+                    "ensure to avoid having uses of it in version control",
+                );
+            }
+        }
+    }
+}
+
+// Get span enclosing entire the token stream.
+fn tts_span(tts: TokenStream) -> Option<Span> {
+    let mut cursor = tts.into_trees();
+    let first = cursor.next()?.span();
+    let span = cursor.last().map_or(first, |tree| first.to(tree.span()));
+    Some(span)
+}