Auto merge of rust-lang#12790 - c410-f3r:blah, r=dswij

Fix rust-lang#12760

Fix rust-lang#12760

```
changelog: [missing_panics_doc]: Ignore panics in compile time
```

Author: bors

clippy_lints/src/doc/missing_headers.rs

@@ -1,3 +1,4 @@
+use super::{DocHeaders, MISSING_ERRORS_DOC, MISSING_PANICS_DOC, MISSING_SAFETY_DOC, UNNECESSARY_SAFETY_DOC};
 use clippy_utils::diagnostics::{span_lint, span_lint_and_note};
 use clippy_utils::ty::{implements_trait, is_type_diagnostic_item};
 use clippy_utils::{is_doc_hidden, return_ty};
@@ -6,15 +7,13 @@ use rustc_lint::LateContext;
 use rustc_middle::ty;
 use rustc_span::{sym, Span};
 
-use super::{DocHeaders, MISSING_ERRORS_DOC, MISSING_PANICS_DOC, MISSING_SAFETY_DOC, UNNECESSARY_SAFETY_DOC};
-
 pub fn check(
     cx: &LateContext<'_>,
     owner_id: OwnerId,
     sig: FnSig<'_>,
     headers: DocHeaders,
     body_id: Option<BodyId>,
-    panic_span: Option<Span>,
+    panic_info: Option<(Span, bool)>,
     check_private_items: bool,
 ) {
     if !check_private_items && !cx.effective_visibilities.is_exported(owner_id.def_id) {
@@ -48,13 +47,13 @@ pub fn check(
         ),
         _ => (),
     }
-    if !headers.panics && panic_span.is_some() {
+    if !headers.panics && panic_info.map_or(false, |el| !el.1) {
         span_lint_and_note(
             cx,
             MISSING_PANICS_DOC,
             span,
             "docs for function which may panic missing `# Panics` section",
-            panic_span,
+            panic_info.map(|el| el.0),
             "first possible panic found here",
         );
     }

clippy_lints/src/doc/mod.rs

@@ -4,7 +4,7 @@ use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
 use clippy_utils::macros::{is_panic, root_macro_call_first_node};
 use clippy_utils::ty::is_type_diagnostic_item;
 use clippy_utils::visitors::Visitable;
-use clippy_utils::{is_entrypoint_fn, is_trait_impl_item, method_chain_args};
+use clippy_utils::{in_constant, is_entrypoint_fn, is_trait_impl_item, method_chain_args};
 use pulldown_cmark::Event::{
     Code, End, FootnoteReference, HardBreak, Html, Rule, SoftBreak, Start, TaskListMarker, Text,
 };
@@ -461,14 +461,14 @@ impl<'tcx> LateLintPass<'tcx> for Documentation {
                     if !(is_entrypoint_fn(cx, item.owner_id.to_def_id()) || in_external_macro(cx.tcx.sess, item.span)) {
                         let body = cx.tcx.hir().body(body_id);
 
-                        let panic_span = FindPanicUnwrap::find_span(cx, cx.tcx.typeck(item.owner_id), body.value);
+                        let panic_info = FindPanicUnwrap::find_span(cx, cx.tcx.typeck(item.owner_id), body.value);
                         missing_headers::check(
                             cx,
                             item.owner_id,
                             sig,
                             headers,
                             Some(body_id),
-                            panic_span,
+                            panic_info,
                             self.check_private_items,
                         );
                     }
@@ -806,6 +806,7 @@ fn check_doc<'a, Events: Iterator<Item = (pulldown_cmark::Event<'a>, Range<usize
 
 struct FindPanicUnwrap<'a, 'tcx> {
     cx: &'a LateContext<'tcx>,
+    is_const: bool,
     panic_span: Option<Span>,
     typeck_results: &'tcx ty::TypeckResults<'tcx>,
 }
@@ -815,14 +816,15 @@ impl<'a, 'tcx> FindPanicUnwrap<'a, 'tcx> {
         cx: &'a LateContext<'tcx>,
         typeck_results: &'tcx ty::TypeckResults<'tcx>,
         body: impl Visitable<'tcx>,
-    ) -> Option<Span> {
+    ) -> Option<(Span, bool)> {
         let mut vis = Self {
             cx,
+            is_const: false,
             panic_span: None,
             typeck_results,
         };
         body.visit(&mut vis);
-        vis.panic_span
+        vis.panic_span.map(|el| (el, vis.is_const))
     }
 }
 
@@ -841,6 +843,7 @@ impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
                     "assert" | "assert_eq" | "assert_ne"
                 )
             {
+                self.is_const = in_constant(self.cx, expr.hir_id);
                 self.panic_span = Some(macro_call.span);
             }
         }

tests/ui/missing_panics_doc.rs

@@ -191,3 +191,11 @@ fn from_declared_macro_should_lint_at_macrosite() {
     // Not here.
     some_macro_that_panics!()
 }
+
+pub fn issue_12760<const N: usize>() {
+    const {
+        if N == 0 {
+            panic!();
+        }
+    }
+}