Merge pull request rust-lang#54 from oli-obk/clippy

Clippy and `assume` intrinsic implementation

Author: solson

src/error.rs

@@ -43,6 +43,7 @@ pub enum EvalError<'tcx> {
     CalledClosureAsFunction,
     VtableForArgumentlessMethod,
     ModifiedConstantMemory,
+    AssumptionNotHeld,
 }
 
 pub type EvalResult<'tcx, T> = Result<T, EvalError<'tcx>>;
@@ -97,6 +98,8 @@ impl<'tcx> Error for EvalError<'tcx> {
                 "tried to call a vtable function without arguments",
             EvalError::ModifiedConstantMemory =>
                 "tried to modify constant memory",
+            EvalError::AssumptionNotHeld =>
+                "`assume` argument was false"
         }
     }
 

src/interpreter/step.rs

@@ -30,7 +30,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
         let mir = self.mir();
         let basic_block = &mir.basic_blocks()[block];
 
-        if let Some(ref stmt) = basic_block.statements.get(stmt_id) {
+        if let Some(stmt) = basic_block.statements.get(stmt_id) {
             let mut new = Ok(0);
             ConstantExtractor {
                 span: stmt.source_info.span,

src/interpreter/terminator.rs

@@ -284,8 +284,11 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
             "sub_with_overflow" => self.intrinsic_with_overflow(mir::BinOp::Sub, &args[0], &args[1], dest, dest_layout)?,
             "mul_with_overflow" => self.intrinsic_with_overflow(mir::BinOp::Mul, &args[0], &args[1], dest, dest_layout)?,
 
-            // FIXME: turn into an assertion to catch wrong `assume` that would cause UB in llvm
-            "assume" => {}
+            "assume" => {
+                if !self.memory.read_bool(args_ptrs[0])? {
+                    return Err(EvalError::AssumptionNotHeld);
+                }
+            }
 
             "copy_nonoverlapping" => {
                 let elem_ty = substs.type_at(0);

src/interpreter/vtable.rs

@@ -20,8 +20,8 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
 
         debug!("get_vtable(trait_ref={:?})", trait_ref);
 
-        let methods: Vec<_> = traits::supertraits(tcx, trait_ref.clone()).flat_map(|trait_ref| {
-            match self.fulfill_obligation(trait_ref.clone()) {
+        let methods: Vec<_> = traits::supertraits(tcx, trait_ref).flat_map(|trait_ref| {
+            match self.fulfill_obligation(trait_ref) {
                 // Should default trait error here?
                 traits::VtableDefaultImpl(_) |
                 traits::VtableBuiltin(_) => {
@@ -164,7 +164,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                 // method could then never be called, so we do not want to
                 // try and trans it, in that case. Issue #23435.
                 if mth.is_provided {
-                    let predicates = mth.method.predicates.predicates.subst(self.tcx, &mth.substs);
+                    let predicates = mth.method.predicates.predicates.subst(self.tcx, mth.substs);
                     if !self.normalize_and_test_predicates(predicates) {
                         debug!("get_vtable_methods: predicates do not hold");
                         return None;

src/memory.rs

@@ -314,7 +314,7 @@ impl<'a, 'tcx> Memory<'a, 'tcx> {
             Some(&FunctionDefinition {
                 def_id,
                 kind: FunctionKind::Closure { ref substs, ref ty }
-            }) => Ok((def_id, substs.clone(), ty.clone())),
+            }) => Ok((def_id, *substs, ty.clone())),
             Some(&FunctionDefinition {
                 kind: FunctionKind::Function { .. }, ..
             }) => Err(EvalError::CalledClosureAsFunction),

tests/compile-fail/assume.rs

@@ -0,0 +1,10 @@
+#![feature(core_intrinsics)]
+
+fn main() {
+    let x = 5;
+    unsafe {
+        std::intrinsics::assume(x < 10);
+        std::intrinsics::assume(x > 1);
+        std::intrinsics::assume(x > 42); //~ ERROR: `assume` argument was false
+    }
+}