From 7160bdb390ef1c9bdcfb0c075b33be39d62860f3 Mon Sep 17 00:00:00 2001
From: hachem <im@hachem.wtf>
Date: Sat, 19 Sep 2026 13:54:59 +0200
Subject: feat: static_assert

---
 ast.h                  |  3 ++-
 eval.c                 | 16 ++++++++++++++++
 examples/assert.sfinae | 12 ++++++++++++
 sfinae.l               |  1 +
 sfinae.y               |  3 +++
 5 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 examples/assert.sfinae

diff --git a/ast.h b/ast.h
index d993c2e..39924b6 100644
--- a/ast.h
+++ b/ast.h
@@ -24,7 +24,8 @@ enum NodeKind
     COND_IS_SAME,
     COND_EQUAL,
     COND_LESS,
-    STMT_EMIT
+    STMT_EMIT,
+    STMT_STATIC_ASSERT
 };
 
 struct Node
diff --git a/eval.c b/eval.c
index eddeb6b..b0ad454 100644
--- a/eval.c
+++ b/eval.c
@@ -168,11 +168,27 @@ static enum RunStatus emit(const struct Node* node)
     return RUN_DONE;
 }
 
+static enum RunStatus static_assert_statement(const struct Node* node)
+{
+    bool truth = false;
+    if (evaluate_condition(node->first, &truth))
+        return RUN_FAILED;
+
+    if (!truth)
+    {
+        (void)complain(node, "static assertion failed, at runtime, which is the best time");
+        return RUN_FAILED;
+    }
+
+    return RUN_DONE;
+}
+
 static enum RunStatus execute_one(const struct Node* node)
 {
     switch (node->kind)
     {
         case STMT_EMIT: return emit(node);
+        case STMT_STATIC_ASSERT: return static_assert_statement(node);
         default: break;
     }
 
diff --git a/examples/assert.sfinae b/examples/assert.sfinae
new file mode 100644
index 0000000..0ef7459
--- /dev/null
+++ b/examples/assert.sfinae
@@ -0,0 +1,12 @@
+::static_assert<
+    ::equal<
+        ::difference<'C', 'A'>,
+        ::sum<::difference<'B', 'A'>, ::difference<'B', 'A'>>
+    >::value
+>::commit;
+
+::static_assert<::is_same<::remove_cv_t<::byte>, ::byte>::value>::commit;
+::emit<::decltype(::difference<'B', 'A'>)>::commit;
+
+
+
diff --git a/sfinae.l b/sfinae.l
index 4832ed0..2ee7a3d 100644
--- a/sfinae.l
+++ b/sfinae.l
@@ -33,6 +33,7 @@ static int fail(const char* message)
 
 "::"                    return TOK_COLONCOLON;
 "emit"                  return TOK_EMIT;
+"static_assert"         return TOK_STATIC_ASSERT;
 "commit"                return TOK_COMMIT;
 "void"                  return TOK_VOID;
 "int32_t"               return TOK_INT32;
diff --git a/sfinae.y b/sfinae.y
index ca3121d..0d7f0ee 100644
--- a/sfinae.y
+++ b/sfinae.y
@@ -17,6 +17,7 @@ void yyerror(const char* message);
 
 %token TOK_COLONCOLON
 %token TOK_EMIT
+%token TOK_STATIC_ASSERT
 %token TOK_COMMIT
 %token TOK_VOID
 %token TOK_INT32
@@ -61,6 +62,8 @@ statements
 statement
     : TOK_COLONCOLON TOK_EMIT '<' type '>' TOK_COLONCOLON TOK_COMMIT
         { $$ = node_unary(STMT_EMIT, $4); }
+    | TOK_COLONCOLON TOK_STATIC_ASSERT '<' condition '>' TOK_COLONCOLON TOK_COMMIT
+        { $$ = node_unary(STMT_STATIC_ASSERT, $4); }
     ;
 
 type
-- 
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