Rollup merge of rust-lang#108090 - WaffleLapkin:if_not_now_then_when……

…, r=oli-obk

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

Resurrection of rust-lang#108079

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);

compiler/rustc_codegen_llvm/src/type_of.rs

@@ -154,7 +154,7 @@ fn struct_llfields<'a, 'tcx>(
     } else {
         debug!("struct_llfields: offset: {:?} stride: {:?}", offset, layout.size);
     }
-    let field_remapping = if padding_used { Some(field_remapping) } else { None };
+    let field_remapping = padding_used.then_some(field_remapping);
     (result, packed, field_remapping)
 }
 

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2024,7 +2024,7 @@ fn linker_with_args<'a>(
         .native_libraries
         .iter()
         .filter_map(|(cnum, libraries)| {
-            (dependency_linkage[cnum.as_usize() - 1] != Linkage::Static).then(|| libraries)
+            (dependency_linkage[cnum.as_usize() - 1] != Linkage::Static).then_some(libraries)
         })
         .flatten();
     for (raw_dylib_name, raw_dylib_imports) in

compiler/rustc_codegen_ssa/src/base.rs

@@ -579,7 +579,7 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
         }
     }
 
-    let metadata_module = if need_metadata_module {
+    let metadata_module = need_metadata_module.then(|| {
         // Emit compressed metadata object.
         let metadata_cgu_name =
             cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("metadata")).to_string();
@@ -594,17 +594,15 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
             if let Err(error) = std::fs::write(&file_name, data) {
                 tcx.sess.emit_fatal(errors::MetadataObjectFileWrite { error });
             }
-            Some(CompiledModule {
+            CompiledModule {
                 name: metadata_cgu_name,
                 kind: ModuleKind::Metadata,
                 object: Some(file_name),
                 dwarf_object: None,
                 bytecode: None,
-            })
+            }
         })
-    } else {
-        None
-    };
+    });
 
     let ongoing_codegen = start_async_codegen(
         backend.clone(),

compiler/rustc_codegen_ssa/src/mir/mod.rs

@@ -167,8 +167,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
         start_bx.set_personality_fn(cx.eh_personality());
     }
 
-    let cleanup_kinds =
-        if base::wants_msvc_seh(cx.tcx().sess) { Some(analyze::cleanup_kinds(&mir)) } else { None };
+    let cleanup_kinds = base::wants_msvc_seh(cx.tcx().sess).then(|| analyze::cleanup_kinds(&mir));
 
     let cached_llbbs: IndexVec<mir::BasicBlock, CachedLlbb<Bx::BasicBlock>> =
         mir.basic_blocks

compiler/rustc_data_structures/src/profiling.rs

@@ -207,8 +207,7 @@ impl SelfProfilerRef {
     /// a measureme event, "verbose" generic activities also print a timing entry to
     /// stderr if the compiler is invoked with -Ztime-passes.
     pub fn verbose_generic_activity(&self, event_label: &'static str) -> VerboseTimingGuard<'_> {
-        let message =
-            if self.print_verbose_generic_activities { Some(event_label.to_owned()) } else { None };
+        let message = self.print_verbose_generic_activities.then(|| event_label.to_owned());
 
         VerboseTimingGuard::start(message, self.generic_activity(event_label))
     }
@@ -222,11 +221,9 @@ impl SelfProfilerRef {
     where
         A: Borrow<str> + Into<String>,
     {
-        let message = if self.print_verbose_generic_activities {
-            Some(format!("{}({})", event_label, event_arg.borrow()))
-        } else {
-            None
-        };
+        let message = self
+            .print_verbose_generic_activities
+            .then(|| format!("{}({})", event_label, event_arg.borrow()));
 
         VerboseTimingGuard::start(message, self.generic_activity_with_arg(event_label, event_arg))
     }

compiler/rustc_errors/src/lib.rs

@@ -1066,29 +1066,26 @@ impl Handler {
     }
 
     pub fn has_errors(&self) -> Option<ErrorGuaranteed> {
-        if self.inner.borrow().has_errors() { Some(ErrorGuaranteed(())) } else { None }
+        self.inner.borrow().has_errors().then(ErrorGuaranteed::unchecked_claim_error_was_emitted)
     }
 
     pub fn has_errors_or_lint_errors(&self) -> Option<ErrorGuaranteed> {
-        if self.inner.borrow().has_errors_or_lint_errors() {
-            Some(ErrorGuaranteed::unchecked_claim_error_was_emitted())
-        } else {
-            None
-        }
+        self.inner
+            .borrow()
+            .has_errors_or_lint_errors()
+            .then(ErrorGuaranteed::unchecked_claim_error_was_emitted)
     }
     pub fn has_errors_or_delayed_span_bugs(&self) -> Option<ErrorGuaranteed> {
-        if self.inner.borrow().has_errors_or_delayed_span_bugs() {
-            Some(ErrorGuaranteed::unchecked_claim_error_was_emitted())
-        } else {
-            None
-        }
+        self.inner
+            .borrow()
+            .has_errors_or_delayed_span_bugs()
+            .then(ErrorGuaranteed::unchecked_claim_error_was_emitted)
     }
     pub fn is_compilation_going_to_fail(&self) -> Option<ErrorGuaranteed> {
-        if self.inner.borrow().is_compilation_going_to_fail() {
-            Some(ErrorGuaranteed::unchecked_claim_error_was_emitted())
-        } else {
-            None
-        }
+        self.inner
+            .borrow()
+            .is_compilation_going_to_fail()
+            .then(ErrorGuaranteed::unchecked_claim_error_was_emitted)
     }
 
     pub fn print_error_count(&self, registry: &Registry) {

compiler/rustc_expand/src/config.rs

@@ -238,12 +238,10 @@ macro_rules! configure {
 impl<'a> StripUnconfigured<'a> {
     pub fn configure<T: HasAttrs + HasTokens>(&self, mut node: T) -> Option<T> {
         self.process_cfg_attrs(&mut node);
-        if self.in_cfg(node.attrs()) {
+        self.in_cfg(node.attrs()).then(|| {
             self.try_configure_tokens(&mut node);
-            Some(node)
-        } else {
-            None
-        }
+            node
+        })
     }
 
     fn try_configure_tokens<T: HasTokens>(&self, node: &mut T) {
@@ -257,7 +255,7 @@ impl<'a> StripUnconfigured<'a> {
 
     fn configure_krate_attrs(&self, mut attrs: ast::AttrVec) -> Option<ast::AttrVec> {
         attrs.flat_map_in_place(|attr| self.process_cfg_attr(attr));
-        if self.in_cfg(&attrs) { Some(attrs) } else { None }
+        self.in_cfg(&attrs).then_some(attrs)
     }
 
     /// Performs cfg-expansion on `stream`, producing a new `AttrTokenStream`.

compiler/rustc_hir/src/hir.rs

@@ -574,14 +574,11 @@ impl<'hir> Generics<'hir> {
 
     /// If there are generic parameters, return where to introduce a new one.
     pub fn span_for_param_suggestion(&self) -> Option<Span> {
-        if self.params.iter().any(|p| self.span.contains(p.span)) {
+        self.params.iter().any(|p| self.span.contains(p.span)).then(|| {
             // `fn foo<A>(t: impl Trait)`
             //          ^ suggest `, T: Trait` here
-            let span = self.span.with_lo(self.span.hi() - BytePos(1)).shrink_to_lo();
-            Some(span)
-        } else {
-            None
-        }
+            self.span.with_lo(self.span.hi() - BytePos(1)).shrink_to_lo()
+        })
     }
 
     /// `Span` where further predicates would be suggested, accounting for trailing commas, like
@@ -639,7 +636,7 @@ impl<'hir> Generics<'hir> {
                 // We include bounds that come from a `#[derive(_)]` but point at the user's code,
                 // as we use this method to get a span appropriate for suggestions.
                 let bs = bound.span();
-                if bs.can_be_used_for_suggestions() { Some(bs.shrink_to_hi()) } else { None }
+                bs.can_be_used_for_suggestions().then(|| bs.shrink_to_hi())
             },
         )
     }

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -259,13 +259,8 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
             }
             TraitItemKind::Const(ty, body_id) => body_id
                 .and_then(|body_id| {
-                    if is_suggestable_infer_ty(ty) {
-                        Some(infer_placeholder_type(
-                            tcx, def_id, body_id, ty.span, item.ident, "constant",
-                        ))
-                    } else {
-                        None
-                    }
+                    is_suggestable_infer_ty(ty)
+                        .then(|| infer_placeholder_type(tcx, def_id, body_id, ty.span, item.ident, "constant",))
                 })
                 .unwrap_or_else(|| icx.to_ty(ty)),
             TraitItemKind::Type(_, Some(ty)) => icx.to_ty(ty),

compiler/rustc_hir_analysis/src/lib.rs

@@ -204,7 +204,7 @@ fn check_main_fn_ty(tcx: TyCtxt<'_>, main_def_id: DefId) {
         let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
         match tcx.hir().find(hir_id) {
             Some(Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, generics, _), .. })) => {
-                generics.params.is_empty().not().then(|| generics.span)
+                generics.params.is_empty().not().then_some(generics.span)
             }
             _ => {
                 span_bug!(tcx.def_span(def_id), "main has a non-function type");