Rollup merge of #108090 - WaffleLapkin:if_not_now_then_when…, r=oli-obk

`if $c:expr { Some($r:expr) } else { None }` =>> `$c.then(|| $r)`

Resurrection of #108079

Author: matthiaskrgr

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -271,7 +271,7 @@ impl<'a> AstValidator<'a> {
 
         self.session.emit_err(InvalidVisibility {
             span: vis.span,
-            implied: if vis.kind.is_pub() { Some(vis.span) } else { None },
+            implied: vis.kind.is_pub().then_some(vis.span),
             note,
         });
     }

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1186,11 +1186,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 return None;
             };
             debug!("checking call args for uses of inner_param: {:?}", args);
-            if args.contains(&Operand::Move(inner_param)) {
-                Some((loc, term))
-            } else {
-                None
-            }
+            args.contains(&Operand::Move(inner_param)).then_some((loc, term))
         }) else {
             debug!("no uses of inner_param found as a by-move call arg");
             return;

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -280,17 +280,10 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
 
         debug!("give_region_a_name: error_region = {:?}", error_region);
         match *error_region {
-            ty::ReEarlyBound(ebr) => {
-                if ebr.has_name() {
-                    let span = tcx.hir().span_if_local(ebr.def_id).unwrap_or(DUMMY_SP);
-                    Some(RegionName {
-                        name: ebr.name,
-                        source: RegionNameSource::NamedEarlyBoundRegion(span),
-                    })
-                } else {
-                    None
-                }
-            }
+            ty::ReEarlyBound(ebr) => ebr.has_name().then(|| {
+                let span = tcx.hir().span_if_local(ebr.def_id).unwrap_or(DUMMY_SP);
+                RegionName { name: ebr.name, source: RegionNameSource::NamedEarlyBoundRegion(span) }
+            }),
 
             ty::ReStatic => {
                 Some(RegionName { name: kw::StaticLifetime, source: RegionNameSource::Static })

compiler/rustc_borrowck/src/type_check/liveness/mod.rs

@@ -50,13 +50,11 @@ pub(super) fn generate<'mir, 'tcx>(
         compute_relevant_live_locals(typeck.tcx(), &free_regions, &body);
     let facts_enabled = use_polonius || AllFacts::enabled(typeck.tcx());
 
-    let polonius_drop_used = if facts_enabled {
+    let polonius_drop_used = facts_enabled.then(|| {
         let mut drop_used = Vec::new();
         polonius::populate_access_facts(typeck, body, location_table, move_data, &mut drop_used);
-        Some(drop_used)
-    } else {
-        None
-    };
+        drop_used
+    });
 
     trace::trace(
         typeck,

compiler/rustc_builtin_macros/src/deriving/debug.rs

@@ -135,19 +135,17 @@ fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>
         }
 
         // `let names: &'static _ = &["field1", "field2"];`
-        let names_let = if is_struct {
+        let names_let = is_struct.then(|| {
             let lt_static = Some(cx.lifetime_static(span));
             let ty_static_ref = cx.ty_ref(span, cx.ty_infer(span), lt_static, ast::Mutability::Not);
-            Some(cx.stmt_let_ty(
+            cx.stmt_let_ty(
                 span,
                 false,
                 Ident::new(sym::names, span),
                 Some(ty_static_ref),
                 cx.expr_array_ref(span, name_exprs),
-            ))
-        } else {
-            None
-        };
+            )
+        });
 
         // `let values: &[&dyn Debug] = &[&&self.field1, &&self.field2];`
         let path_debug = cx.path_global(span, cx.std_path(&[sym::fmt, sym::Debug]));

compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

@@ -942,13 +942,11 @@ impl<'a> MethodDef<'a> {
         let mut nonself_arg_tys = Vec::new();
         let span = trait_.span;
 
-        let explicit_self = if self.explicit_self {
+        let explicit_self = self.explicit_self.then(|| {
             let (self_expr, explicit_self) = ty::get_explicit_self(cx, span);
             selflike_args.push(self_expr);
-            Some(explicit_self)
-        } else {
-            None
-        };
+            explicit_self
+        });
 
         for (ty, name) in self.nonself_args.iter() {
             let ast_ty = ty.to_ty(cx, span, type_ident, generics);

compiler/rustc_builtin_macros/src/standard_library_imports.rs

@@ -62,7 +62,7 @@ pub fn inject(
     // the one with the prelude.
     let name = names[0];
 
-    let root = (edition == Edition2015).then(|| kw::PathRoot);
+    let root = (edition == Edition2015).then_some(kw::PathRoot);
 
     let import_path = root
         .iter()

compiler/rustc_codegen_cranelift/src/driver/aot.rs

@@ -248,17 +248,13 @@ fn reuse_workproduct_for_cgu(
             dwarf_object: None,
             bytecode: None,
         },
-        module_global_asm: if has_global_asm {
-            Some(CompiledModule {
-                name: cgu.name().to_string(),
-                kind: ModuleKind::Regular,
-                object: Some(obj_out_global_asm),
-                dwarf_object: None,
-                bytecode: None,
-            })
-        } else {
-            None
-        },
+        module_global_asm: has_global_asm.then(|| CompiledModule {
+            name: cgu.name().to_string(),
+            kind: ModuleKind::Regular,
+            object: Some(obj_out_global_asm),
+            dwarf_object: None,
+            bytecode: None,
+        }),
         existing_work_product: Some((cgu.work_product_id(), work_product)),
     })
 }

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -412,11 +412,7 @@ fn get_pgo_sample_use_path(config: &ModuleConfig) -> Option<CString> {
 }
 
 fn get_instr_profile_output_path(config: &ModuleConfig) -> Option<CString> {
-    if config.instrument_coverage {
-        Some(CString::new("default_%m_%p.profraw").unwrap())
-    } else {
-        None
-    }
+    config.instrument_coverage.then(|| CString::new("default_%m_%p.profraw").unwrap())
 }
 
 pub(crate) unsafe fn llvm_optimize(
@@ -451,11 +447,10 @@ pub(crate) unsafe fn llvm_optimize(
         None
     };
 
-    let mut llvm_profiler = if cgcx.prof.llvm_recording_enabled() {
-        Some(LlvmSelfProfiler::new(cgcx.prof.get_self_profiler().unwrap()))
-    } else {
-        None
-    };
+    let mut llvm_profiler = cgcx
+        .prof
+        .llvm_recording_enabled()
+        .then(|| LlvmSelfProfiler::new(cgcx.prof.get_self_profiler().unwrap()));
 
     let llvm_selfprofiler =
         llvm_profiler.as_mut().map(|s| s as *mut _ as *mut c_void).unwrap_or(std::ptr::null_mut());

compiler/rustc_codegen_llvm/src/context.rs

@@ -402,12 +402,8 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
 
         let (llcx, llmod) = (&*llvm_module.llcx, llvm_module.llmod());
 
-        let coverage_cx = if tcx.sess.instrument_coverage() {
-            let covctx = coverageinfo::CrateCoverageContext::new();
-            Some(covctx)
-        } else {
-            None
-        };
+        let coverage_cx =
+            tcx.sess.instrument_coverage().then(coverageinfo::CrateCoverageContext::new);
 
         let dbg_cx = if tcx.sess.opts.debuginfo != DebugInfo::None {
             let dctx = debuginfo::CodegenUnitDebugContext::new(llmod);