[PATCH 39/73] options: Add support for -std=c23, -std=c2x and -std=gnu23

[Bart Van Assche <bvanassche@acm.org>]

Add STANDARD_C23 and STANDARD_GNU23 to enum standard, handle the c23,
c2x, iso9899:2024, gnu23, and gnu2x arguments to -std=, and set
__STDC_VERSION__ to 202311L when targeting C23 so that users and build
systems can select ISO C23 and GNU23 language modes and feature-test
macros.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 options.c                     |  5 +++++
 options.h                     |  2 ++
 predefine.c                   |  4 ++++
 validation/c23-stdc-version.c | 11 +++++++++++
 4 files changed, 22 insertions(+)
 create mode 100644 validation/c23-stdc-version.c

diff --git a/options.c b/options.c
index 5aa3290e07da..c140a912e8e9 100644
--- a/options.c
+++ b/options.c
@@ -797,6 +797,11 @@ static char **handle_switch_s(const char *arg, char **next)
 		else if (!strcmp(arg, "gnu17") ||
 			 !strcmp(arg, "gnu18"))
 			standard = STANDARD_GNU17;
+		else if (!strcmp(arg, "c23") || !strcmp(arg, "c2x") ||
+			 !strcmp(arg, "iso9899:2024"))
+			standard = STANDARD_C23;
+		else if (!strcmp(arg, "gnu23") || !strcmp(arg, "gnu2x"))
+			standard = STANDARD_GNU23;
 
 		else
 			die("Unsupported C dialect");
diff --git a/options.h b/options.h
index c2a9551a78e2..94eb7d10e362 100644
--- a/options.h
+++ b/options.h
@@ -27,6 +27,8 @@ enum standard {
 	STANDARD_GNU11 = STANDARD_C11 | STANDARD_GNU,
 	STANDARD_C17,
 	STANDARD_GNU17 = STANDARD_C17 | STANDARD_GNU,
+	STANDARD_C23,
+	STANDARD_GNU23 = STANDARD_C23 | STANDARD_GNU,
 };
 
 extern int die_if_error;
diff --git a/predefine.c b/predefine.c
index 5b0f0caf4c35..d6ab0785abad 100644
--- a/predefine.c
+++ b/predefine.c
@@ -111,6 +111,10 @@ void predefined_macros(void)
 	case STANDARD_GNU17:
 		predefine("__STDC_VERSION__", 1, "201710L");
 		break;
+	case STANDARD_C23:
+	case STANDARD_GNU23:
+		predefine("__STDC_VERSION__", 1, "202311L");
+		break;
 	}
 	if (!(standard & STANDARD_GNU) && (standard != STANDARD_NONE))
 		predefine("__STRICT_ANSI__", 1, "1");
diff --git a/validation/c23-stdc-version.c b/validation/c23-stdc-version.c
new file mode 100644
index 000000000000..a2903362f2f3
--- /dev/null
+++ b/validation/c23-stdc-version.c
@@ -0,0 +1,11 @@
+__STDC_VERSION__
+
+/*
+ * check-name: c23-stdc-version
+ * check-command: sparse -E -std=c23 $file
+ *
+ * check-output-start
+
+202311L
+ * check-output-end
+ */