Auto merge of rust-lang#16705 - regexident:resolve-callable-exprs, r=Veykril

Add public function for resolving callable AST exprs to their HIR equivalents

(the PR is motivated by an outside use of the `ra_ap_hir` crate that would benefit from being able to walk a `hir::Function`'s AST, resolving callable exprs within to their HIR equivalents)

Author: bors

crates/hir/src/semantics.rs

@@ -1120,6 +1120,10 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(pat.syntax())?.binding_mode_of_pat(self.db, pat)
     }
 
+    pub fn resolve_expr_as_callable(&self, call: &ast::Expr) -> Option<Callable> {
+        self.analyze(call.syntax())?.resolve_expr_as_callable(self.db, call)
+    }
+
     pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
         self.analyze(call.syntax())?.resolve_method_call(self.db, call)
     }

crates/hir/src/source_analyzer.rs

@@ -303,6 +303,14 @@ impl SourceAnalyzer {
         }
     }
 
+    pub(crate) fn resolve_expr_as_callable(
+        &self,
+        db: &dyn HirDatabase,
+        call: &ast::Expr,
+    ) -> Option<Callable> {
+        self.type_of_expr(db, &call.clone())?.0.as_callable(db)
+    }
+
     pub(crate) fn resolve_field(
         &self,
         db: &dyn HirDatabase,