Rollup merge of #149470 - Zalathar:prepared-conditions, r=jieyouxu

compiletest: Prepare ignore/only conditions once in advance, without a macro

Compiletest has historically handled `ignore-*` and `only-*` directives in an extremely confusing way that makes the code hard to understand and hard to modify.

This PR therefore takes an important step away from that older design by instead evaluating a set of named boolean "conditions" in advance, and then using those conditions to help determine whether a particular directive should cause its test to be ignored or not.

As usual, there's more cleanup that I want to do here, but I've left most of it for future work to help keep this PR manageable.

r? jieyouxu

Author: Zalathar

src/tools/compiletest/Cargo.toml

@@ -9,6 +9,9 @@ doctest = false
 [[bin]]
 name = "compiletest"
 path = "src/bin/main.rs"
+# The compiletest binary crate is a tiny stub that shouldn't contain any unit
+# tests of its own; all of the logic is in the library crate.
+test = false
 
 [dependencies]
 # tidy-alphabetical-start

src/tools/compiletest/src/directives.rs

@@ -34,12 +34,18 @@ mod needs;
 mod tests;
 
 pub struct DirectivesCache {
+    /// "Conditions" used by `ignore-*` and `only-*` directives, prepared in
+    /// advance so that they don't have to be evaluated repeatedly.
+    cfg_conditions: cfg::PreparedConditions,
     needs: CachedNeedsConditions,
 }
 
 impl DirectivesCache {
     pub fn load(config: &Config) -> Self {
-        Self { needs: CachedNeedsConditions::load(config) }
+        Self {
+            cfg_conditions: cfg::prepare_conditions(config),
+            needs: CachedNeedsConditions::load(config),
+        }
     }
 }
 
@@ -1058,8 +1064,8 @@ pub(crate) fn make_test_description(
                 };
             }
 
-            decision!(cfg::handle_ignore(config, ln));
-            decision!(cfg::handle_only(config, ln));
+            decision!(cfg::handle_ignore(&cache.cfg_conditions, ln));
+            decision!(cfg::handle_only(&cache.cfg_conditions, ln));
             decision!(needs::handle_needs(&cache.needs, config, ln));
             decision!(ignore_llvm(config, ln));
             decision!(ignore_backends(config, ln));