X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_lints%2Fsrc%2Fassertions_on_constants.rs;h=874fff1f0814fb8a963123b23fcfc338e8f4809f;hb=e5a5b0a0774625eebbe7b29c67b49dc6431544d1;hp=32ca1cc1bb99fea654cee0a0f7703a96c2e6b6f8;hpb=e92c48989f1c8a3356cde3829c88408da9d8c983;p=rust.git

diff --git a/clippy_lints/src/assertions_on_constants.rs b/clippy_lints/src/assertions_on_constants.rs
index 32ca1cc1bb9..874fff1f081 100644
--- a/clippy_lints/src/assertions_on_constants.rs
+++ b/clippy_lints/src/assertions_on_constants.rs
@@ -1,9 +1,12 @@
-use rustc::hir::{Expr, ExprKind};
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_lint_pass, declare_tool_lint};
-
 use crate::consts::{constant, Constant};
-use crate::utils::{in_macro_or_desugar, is_direct_expn_of, is_expn_of, span_help_and_lint};
+use crate::utils::paths;
+use crate::utils::{is_direct_expn_of, is_expn_of, match_function_call, snippet_opt, span_help_and_lint};
+use if_chain::if_chain;
+use rustc::declare_lint_pass;
+use rustc::hir::*;
+use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use rustc_session::declare_tool_lint;
+use syntax::ast::LitKind;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for `assert!(true)` and `assert!(false)` calls.
@@ -31,39 +34,115 @@
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
-        let lint_assert_cb = |is_debug_assert: bool| {
-            if let ExprKind::Unary(_, ref lit) = e.node {
-                if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, lit) {
-                    if is_true {
-                        span_help_and_lint(
-                            cx,
-                            ASSERTIONS_ON_CONSTANTS,
-                            e.span,
-                            "`assert!(true)` will be optimized out by the compiler",
-                            "remove it",
-                        );
-                    } else if !is_debug_assert {
-                        span_help_and_lint(
-                            cx,
-                            ASSERTIONS_ON_CONSTANTS,
-                            e.span,
-                            "`assert!(false)` should probably be replaced",
-                            "use `panic!()` or `unreachable!()`",
-                        );
-                    }
-                }
-            }
+        let lint_true = || {
+            span_help_and_lint(
+                cx,
+                ASSERTIONS_ON_CONSTANTS,
+                e.span,
+                "`assert!(true)` will be optimized out by the compiler",
+                "remove it",
+            );
+        };
+        let lint_false_without_message = || {
+            span_help_and_lint(
+                cx,
+                ASSERTIONS_ON_CONSTANTS,
+                e.span,
+                "`assert!(false)` should probably be replaced",
+                "use `panic!()` or `unreachable!()`",
+            );
         };
+        let lint_false_with_message = |panic_message: String| {
+            span_help_and_lint(
+                cx,
+                ASSERTIONS_ON_CONSTANTS,
+                e.span,
+                &format!("`assert!(false, {})` should probably be replaced", panic_message),
+                &format!("use `panic!({})` or `unreachable!({})`", panic_message, panic_message),
+            )
+        };
+
         if let Some(debug_assert_span) = is_expn_of(e.span, "debug_assert") {
-            if in_macro_or_desugar(debug_assert_span) {
+            if debug_assert_span.from_expansion() {
                 return;
             }
-            lint_assert_cb(true);
+            if_chain! {
+                if let ExprKind::Unary(_, ref lit) = e.kind;
+                if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, lit);
+                if is_true;
+                then {
+                    lint_true();
+                }
+            };
         } else if let Some(assert_span) = is_direct_expn_of(e.span, "assert") {
-            if in_macro_or_desugar(assert_span) {
+            if assert_span.from_expansion() {
                 return;
             }
-            lint_assert_cb(false);
+            if let Some(assert_match) = match_assert_with_message(&cx, e) {
+                match assert_match {
+                    // matched assert but not message
+                    AssertKind::WithoutMessage(false) => lint_false_without_message(),
+                    AssertKind::WithoutMessage(true) | AssertKind::WithMessage(_, true) => lint_true(),
+                    AssertKind::WithMessage(panic_message, false) => lint_false_with_message(panic_message),
+                };
+            }
+        }
+    }
+}
+
+/// Result of calling `match_assert_with_message`.
+enum AssertKind {
+    WithMessage(String, bool),
+    WithoutMessage(bool),
+}
+
+/// Check if the expression matches
+///
+/// ```rust,ignore
+/// match { let _t = !c; _t } {
+///     true => {
+///         {
+///             ::std::rt::begin_panic(message, _)
+///         }
+///     }
+///     _ => { }
+/// };
+/// ```
+///
+/// where `message` is any expression and `c` is a constant bool.
+fn match_assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<AssertKind> {
+    if_chain! {
+        if let ExprKind::Match(ref expr, ref arms, _) = expr.kind;
+        // matches { let _t = expr; _t }
+        if let ExprKind::DropTemps(ref expr) = expr.kind;
+        if let ExprKind::Unary(UnOp::UnNot, ref expr) = expr.kind;
+        // bind the first argument of the `assert!` macro
+        if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, expr);
+        // arm 1 pattern
+        if let PatKind::Lit(ref lit_expr) = arms[0].pat.kind;
+        if let ExprKind::Lit(ref lit) = lit_expr.kind;
+        if let LitKind::Bool(true) = lit.node;
+        // arm 1 block
+        if let ExprKind::Block(ref block, _) = arms[0].body.kind;
+        if block.stmts.len() == 0;
+        if let Some(block_expr) = &block.expr;
+        if let ExprKind::Block(ref inner_block, _) = block_expr.kind;
+        if let Some(begin_panic_call) = &inner_block.expr;
+        // function call
+        if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC);
+        if args.len() == 2;
+        // bind the second argument of the `assert!` macro if it exists
+        if let panic_message = snippet_opt(cx, args[0].span);
+        // second argument of begin_panic is irrelevant
+        // as is the second match arm
+        then {
+            // an empty message occurs when it was generated by the macro
+            // (and not passed by the user)
+            return panic_message
+                .filter(|msg| !msg.is_empty())
+                .map(|msg| AssertKind::WithMessage(msg, is_true))
+                .or(Some(AssertKind::WithoutMessage(is_true)));
         }
     }
+    None
 }