Null-check function pointer invocation #1573.

releasenotes.md

@@ -18,6 +18,7 @@
 - Defer resolution of declarations when looked up in `def` aliased #1559.
 - Adding constants to the Json AST #1540
 - Adding info to the globals inside Json AST #1541
+- Null-check function pointer invocation #1573.
 
 ### Fixes
 - `Unsupported int[*] $x = { 1, 2, 3, 4 }` #1489.

src/compiler/llvm_codegen_expr.c

@@ -6206,6 +6206,16 @@ static void llvm_emit_call_expr(GenContext *c, BEValue *result_value, Expr *expr
 		// 1d. Load it as a value
 		func = llvm_load_value_store(c, &func_value);
 
+		if (safe_mode_enabled())
+		{
+			LLVMValueRef check = LLVMBuildICmp(c->builder, LLVMIntEQ, func, LLVMConstNull(c->ptr_type), "checknull");
+			scratch_buffer_clear();
+			scratch_buffer_append("Calling null function pointer, '");
+			span_to_scratch(function->span);
+			scratch_buffer_append("' was null.");
+			llvm_emit_panic_on_true(c, check, scratch_buffer_to_string(), function->span, NULL, NULL, NULL);
+		}
+
 		// 1e. Calculate the function type
 		func_type = llvm_get_type(c, type);
 	}

test/test_suite/functions/func_ptr_null.check.c3t

@@ -0,0 +1,43 @@
+// #target: macos-aarch64
+// #safe: yes
+module test;
+def TestFn = fn void();
+
+fn int main()
+{
+  TestFn foo;
+  foo();
+  return 0;
+}
+
+/* #expect: test.ll
+
+
+define i32 @main() #0 {
+entry:
+  %foo = alloca ptr, align 8
+  %taddr = alloca %"char[]", align 8
+  %taddr1 = alloca %"char[]", align 8
+  %taddr2 = alloca %"char[]", align 8
+  store ptr null, ptr %foo, align 8
+  %0 = load ptr, ptr %foo, align 8
+  %checknull = icmp eq ptr %0, null
+  %1 = call i1 @llvm.expect.i1(i1 %checknull, i1 false)
+  br i1 %1, label %panic, label %checkok
+
+checkok:                                          ; preds = %entry
+  call void %0()
+  ret i32 0
+
+panic:                                            ; preds = %entry
+  store %"char[]" { ptr @.panic_msg, i64 46 }, ptr %taddr, align 8
+  %2 = load [2 x i64], ptr %taddr, align 8
+  store %"char[]" { ptr @.file, i64 22 }, ptr %taddr1, align 8
+  %3 = load [2 x i64], ptr %taddr1, align 8
+  store %"char[]" { ptr @.func, i64 4 }, ptr %taddr2, align 8
+  %4 = load [2 x i64], ptr %taddr2, align 8
+  %5 = load ptr, ptr @std.core.builtin.panic, align 8
+  call void %5([2 x i64] %2, [2 x i64] %3, [2 x i64] %4, i32 7)
+  unreachable
+}
+