From 3b79c1d1483f02f00ee9e3cbdd1d0537dd66269e Mon Sep 17 00:00:00 2001
From: =?utf8?q?Alexis=20Laferri=C3=A8re?= <alexis.laf@xymus.net>
Date: Wed, 23 Aug 2017 11:40:27 -0400
Subject: [PATCH] nitc & niti: explain failed assert to stderr
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Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
---
 src/compiler/abstract_compiler.nit    |   22 ++++++++++++++++++++++
 src/interpreter/naive_interpreter.nit |   17 +++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/src/compiler/abstract_compiler.nit b/src/compiler/abstract_compiler.nit
index a3a0bc8..a21456d 100644
--- a/src/compiler/abstract_compiler.nit
+++ b/src/compiler/abstract_compiler.nit
@@ -24,6 +24,7 @@ import c_tools
 private import annotation
 import mixin
 import counter
+private import explain_assert_api
 
 # Add compiling options
 redef class ToolContext
@@ -3606,6 +3607,9 @@ redef class AAssertExpr
 		var cond = v.expr_bool(self.n_expr)
 		v.add("if (unlikely(!{cond})) \{")
 		v.stmt(self.n_else)
+
+		explain_assert v
+
 		var nid = self.n_id
 		if nid != null then
 			v.add_abort("Assert '{nid.text}' failed")
@@ -3614,6 +3618,24 @@ redef class AAssertExpr
 		end
 		v.add("\}")
 	end
+
+	# Explain assert if it fails
+	private fun explain_assert(v: AbstractCompilerVisitor)
+	do
+		var explain_assert_str = explain_assert_str
+		if explain_assert_str == null then return
+
+		var nas = v.compiler.modelbuilder.model.get_mclasses_by_name("NativeArray")
+		if nas == null then return
+
+		var expr = explain_assert_str.expr(v)
+		if expr == null then return
+
+		var cstr = v.send(v.get_property("to_cstring", expr.mtype), [expr])
+		if cstr == null then return
+
+		v.add "PRINT_ERROR(\"Runtime assert: %s\\n\", {cstr});"
+	end
 end
 
 redef class AOrExpr
diff --git a/src/interpreter/naive_interpreter.nit b/src/interpreter/naive_interpreter.nit
index 616977a..6c899bd 100644
--- a/src/interpreter/naive_interpreter.nit
+++ b/src/interpreter/naive_interpreter.nit
@@ -23,6 +23,7 @@ private import parser::tables
 import mixin
 import primitive_types
 private import model::serialize_model
+private import frontend::explain_assert_api
 
 redef class ToolContext
 	# --discover-call-trace
@@ -1875,6 +1876,22 @@ redef class AAssertExpr
 		if not cond.is_true then
 			v.stmt(self.n_else)
 			if v.is_escaping then return
+
+			# Explain assert if it fails
+			var explain_assert_str = explain_assert_str
+			if explain_assert_str != null then
+				var i = v.expr(explain_assert_str)
+				if i isa MutableInstance then
+					var res = v.send(v.force_get_primitive_method("to_cstring", i.mtype), [i])
+					if res != null then
+						var val = res.val
+						if val != null then
+							print_error "Runtime assert: {val.to_s}"
+						end
+					end
+				end
+			end
+
 			var nid = self.n_id
 			if nid != null then
 				fatal(v, "Assert '{nid.text}' failed")
-- 
1.7.9.5