Auto merge of rust-lang#17419 - ishanjain28:filter_builtin_macro_expansion, r=Veykril

Filter builtin macro expansion

This PR adds a filter on the types of built in macros that are allowed to be expanded.

Currently, This list of allowed macros contains, `stringify, cfg, core_panic, std_panic, concat, concat_bytes, include, include_str, include_bytes, env` and `option_env`.

Fixes rust-lang#14177

Author: bors

src/tools/rust-analyzer/crates/hir/src/semantics.rs

@@ -19,8 +19,12 @@ use hir_def::{
     AsMacroCall, DefWithBodyId, FunctionId, MacroId, TraitId, VariantId,
 };
 use hir_expand::{
-    attrs::collect_attrs, db::ExpandDatabase, files::InRealFile, name::AsName, InMacroFile,
-    MacroCallId, MacroFileId, MacroFileIdExt,
+    attrs::collect_attrs,
+    builtin_fn_macro::{BuiltinFnLikeExpander, EagerExpander},
+    db::ExpandDatabase,
+    files::InRealFile,
+    name::AsName,
+    InMacroFile, MacroCallId, MacroFileId, MacroFileIdExt,
 };
 use itertools::Itertools;
 use rustc_hash::{FxHashMap, FxHashSet};
@@ -324,6 +328,48 @@ impl<'db> SemanticsImpl<'db> {
         Some(node)
     }
 
+    /// Expands the macro if it isn't one of the built-in ones that expand to custom syntax or dummy
+    /// expansions.
+    pub fn expand_allowed_builtins(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
+        let sa = self.analyze_no_infer(macro_call.syntax())?;
+
+        let macro_call = InFile::new(sa.file_id, macro_call);
+        let file_id = if let Some(call) =
+            <ast::MacroCall as crate::semantics::ToDef>::to_def(self, macro_call)
+        {
+            call.as_macro_file()
+        } else {
+            sa.expand(self.db, macro_call)?
+        };
+        let macro_call = self.db.lookup_intern_macro_call(file_id.macro_call_id);
+
+        let skip = matches!(
+            macro_call.def.kind,
+            hir_expand::MacroDefKind::BuiltIn(
+                _,
+                BuiltinFnLikeExpander::Column
+                    | BuiltinFnLikeExpander::File
+                    | BuiltinFnLikeExpander::ModulePath
+                    | BuiltinFnLikeExpander::Asm
+                    | BuiltinFnLikeExpander::LlvmAsm
+                    | BuiltinFnLikeExpander::GlobalAsm
+                    | BuiltinFnLikeExpander::LogSyntax
+                    | BuiltinFnLikeExpander::TraceMacros
+                    | BuiltinFnLikeExpander::FormatArgs
+                    | BuiltinFnLikeExpander::FormatArgsNl
+                    | BuiltinFnLikeExpander::ConstFormatArgs,
+            ) | hir_expand::MacroDefKind::BuiltInEager(_, EagerExpander::CompileError)
+        );
+        if skip {
+            // these macros expand to custom builtin syntax and/or dummy things, no point in
+            // showing these to the user
+            return None;
+        }
+
+        let node = self.parse_or_expand(file_id.into());
+        Some(node)
+    }
+
     /// If `item` has an attribute macro attached to it, expands it.
     pub fn expand_attr_macro(&self, item: &ast::Item) -> Option<SyntaxNode> {
         let src = self.wrap_node_infile(item.clone());

src/tools/rust-analyzer/crates/ide/src/expand_macro.rs

@@ -111,9 +111,10 @@ fn expand_macro_recur(
     macro_call: &ast::Item,
 ) -> Option<SyntaxNode> {
     let expanded = match macro_call {
-        item @ ast::Item::MacroCall(macro_call) => {
-            sema.expand_attr_macro(item).or_else(|| sema.expand(macro_call))?.clone_for_update()
-        }
+        item @ ast::Item::MacroCall(macro_call) => sema
+            .expand_attr_macro(item)
+            .or_else(|| sema.expand_allowed_builtins(macro_call))?
+            .clone_for_update(),
         item => sema.expand_attr_macro(item)?.clone_for_update(),
     };
     expand(sema, expanded)
@@ -228,6 +229,29 @@ mod tests {
         expect.assert_eq(&actual);
     }
 
+    #[test]
+    fn expand_allowed_builtin_macro() {
+        check(
+            r#"
+//- minicore: concat
+$0concat!("test", 10, 'b', true);"#,
+            expect![[r#"
+                concat!
+                "test10btrue""#]],
+        );
+    }
+
+    #[test]
+    fn do_not_expand_disallowed_macro() {
+        let (analysis, pos) = fixture::position(
+            r#"
+//- minicore: asm
+$0asm!("0x300, x0");"#,
+        );
+        let expansion = analysis.expand_macro(pos).unwrap();
+        assert!(expansion.is_none());
+    }
+
     #[test]
     fn macro_expand_as_keyword() {
         check(