[src/trunk]: src/usr.bin/xlint/lint1 lint: fix parsing of _Generic selection ...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2797ab0839a5
branches:  trunk
changeset: 984209:2797ab0839a5
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Jun 27 21:30:46 2021 +0000

description:
lint: fix parsing of _Generic selection expressions

Previously, lint accepted comma-expressions where only
assignment-expressions are allowed.

This change does not make a difference in practice though since lint is
usually only run on source code that properly compiles.  Nevertheless,
rather be precise and accurate since the grammar might some day be
reused on less reliable input.

diffstat:

 tests/usr.bin/xlint/lint1/c11_generic_expression.c   |   6 +++---
 tests/usr.bin/xlint/lint1/c11_generic_expression.exp |   3 ++-
 usr.bin/xlint/lint1/cgram.y                          |  14 +++++++++-----
 3 files changed, 14 insertions(+), 9 deletions(-)

diffs (82 lines):

diff -r 133ba54051b0 -r 2797ab0839a5 tests/usr.bin/xlint/lint1/c11_generic_expression.c
--- a/tests/usr.bin/xlint/lint1/c11_generic_expression.c        Sun Jun 27 21:16:40 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/c11_generic_expression.c        Sun Jun 27 21:30:46 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: c11_generic_expression.c,v 1.4 2021/06/27 21:16:40 rillig Exp $        */
+/*     $NetBSD: c11_generic_expression.c,v 1.5 2021/06/27 21:30:46 rillig Exp $        */
 # 3 "c11_generic_expression.c"
 
 /*
@@ -69,9 +69,9 @@
 const int *
 comma_expression(char first, double second)
 {
-       return _Generic(first, second,  /* FIXME */
+       return _Generic(first, second,  /* expect: syntax error 'second' */
            char: "first",
            double: 2.0
        );
-       /* expect-1: mismatch (pointer to const int) and (double) [211] */
+       /* expect+1: without returning value [217] */
 }
diff -r 133ba54051b0 -r 2797ab0839a5 tests/usr.bin/xlint/lint1/c11_generic_expression.exp
--- a/tests/usr.bin/xlint/lint1/c11_generic_expression.exp      Sun Jun 27 21:16:40 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/c11_generic_expression.exp      Sun Jun 27 21:30:46 2021 +0000
@@ -2,4 +2,5 @@
 c11_generic_expression.c(21): warning: argument 'var' unused in function 'classify_type_without_default' [231]
 c11_generic_expression.c(37): warning: argument 'var' unused in function 'classify_type_with_default' [231]
 c11_generic_expression.c(53): warning: argument 'c' unused in function 'classify_char' [231]
-c11_generic_expression.c(75): error: return value type mismatch (pointer to const int) and (double) [211]
+c11_generic_expression.c(72): error: syntax error 'second' [249]
+c11_generic_expression.c(77): warning: function comma_expression falls off bottom without returning value [217]
diff -r 133ba54051b0 -r 2797ab0839a5 usr.bin/xlint/lint1/cgram.y
--- a/usr.bin/xlint/lint1/cgram.y       Sun Jun 27 21:16:40 2021 +0000
+++ b/usr.bin/xlint/lint1/cgram.y       Sun Jun 27 21:30:46 2021 +0000
@@ -1,5 +1,5 @@
 %{
-/* $NetBSD: cgram.y,v 1.237 2021/06/27 20:47:13 rillig Exp $ */
+/* $NetBSD: cgram.y,v 1.238 2021/06/27 21:30:46 rillig Exp $ */
 
 /*
  * Copyright (c) 1996 Christopher G. Demetriou.  All Rights Reserved.
@@ -35,7 +35,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: cgram.y,v 1.237 2021/06/27 20:47:13 rillig Exp $");
+__RCSID("$NetBSD: cgram.y,v 1.238 2021/06/27 21:30:46 rillig Exp $");
 #endif
 
 #include <limits.h>
@@ -323,6 +323,7 @@
 %type  <y_sym>         parameter_type_list
 %type  <y_sym>         parameter_declaration
 %type  <y_tnode>       expr
+%type  <y_tnode>       assignment_expression
 %type  <y_tnode>       gcc_statement_expr_list
 %type  <y_tnode>       gcc_statement_expr_item
 %type  <y_tnode>       term
@@ -1682,10 +1683,9 @@
          }
        ;
 
-/* TODO: C11 6.5.1.1 says "assignment-expression", not plain "expr". */
-/* TODO: c11ism */
 generic_selection:             /* C11 6.5.1.1 */
-         T_GENERIC T_LPAREN expr T_COMMA generic_assoc_list T_RPAREN {
+         T_GENERIC T_LPAREN assignment_expression T_COMMA
+           generic_assoc_list T_RPAREN {
                /* generic selection requires C11 or later */
                c11ism(345);
                $$ = build_generic_selection($3, $5);
@@ -1911,6 +1911,10 @@
          }
        ;
 
+assignment_expression:         /* C99 6.5.16 */
+         expr %prec T_ASSIGN
+       ;
+
 term:
          T_NAME {
                /* XXX really necessary? */