From c390f55e727c8f4ace2eb7992403bf8332a22126 Mon Sep 17 00:00:00 2001
From: Techatrix <techatrix@mailbox.org>
Date: Wed, 19 Feb 2025 09:34:25 +0100
Subject: [PATCH 1/4] add a standalone test for autoconf style addConfigHeader

---
 test/standalone/build.zig.zon             |  3 +++
 test/standalone/config_header/build.zig   | 22 ++++++++++++++++++++++
 test/standalone/config_header/config.h    | 14 ++++++++++++++
 test/standalone/config_header/config.h.in | 12 ++++++++++++
 4 files changed, 51 insertions(+)
 create mode 100644 test/standalone/config_header/build.zig
 create mode 100644 test/standalone/config_header/config.h
 create mode 100644 test/standalone/config_header/config.h.in

diff --git a/test/standalone/build.zig.zon b/test/standalone/build.zig.zon
index 9863e7cc6d..db1c7125a7 100644
--- a/test/standalone/build.zig.zon
+++ b/test/standalone/build.zig.zon
@@ -186,6 +186,9 @@
         .omit_cfi = .{
             .path = "omit_cfi",
         },
+        .config_header = .{
+            .path = "config_header",
+        },
     },
     .paths = .{
         "build.zig",
diff --git a/test/standalone/config_header/build.zig b/test/standalone/config_header/build.zig
new file mode 100644
index 0000000000..0268b642a7
--- /dev/null
+++ b/test/standalone/config_header/build.zig
@@ -0,0 +1,22 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const config_header = b.addConfigHeader(
+        .{ .style = .{ .autoconf = b.path("config.h.in") } },
+        .{
+            .SOME_NO = null,
+            .SOME_TRUE = true,
+            .SOME_FALSE = false,
+            .SOME_ZERO = 0,
+            .SOME_ONE = 1,
+            .SOME_TEN = 10,
+            .SOME_ENUM_LITERAL = .@"test",
+            .SOME_STRING = "test",
+        },
+    );
+
+    const check_config_header = b.addCheckFile(config_header.getOutput(), .{ .expected_exact = @embedFile("config.h") });
+
+    const test_step = b.step("test", "Test it");
+    test_step.dependOn(&check_config_header.step);
+}
diff --git a/test/standalone/config_header/config.h b/test/standalone/config_header/config.h
new file mode 100644
index 0000000000..961fdc564f
--- /dev/null
+++ b/test/standalone/config_header/config.h
@@ -0,0 +1,14 @@
+/* This file was generated by ConfigHeader using the Zig Build System. */
+/* Some Comment */
+
+int foo();
+
+/* #undef SOME_NO */
+#define SOME_TRUE 1
+#define SOME_FALSE 0
+#define SOME_ZERO 0
+#define SOME_ONE 1
+#define SOME_TEN 10
+#define SOME_ENUM_LITERAL test
+#define SOME_STRING "test"
+
diff --git a/test/standalone/config_header/config.h.in b/test/standalone/config_header/config.h.in
new file mode 100644
index 0000000000..0bb37a419c
--- /dev/null
+++ b/test/standalone/config_header/config.h.in
@@ -0,0 +1,12 @@
+/* Some Comment */
+
+int foo();
+
+#undef SOME_NO
+#undef SOME_TRUE
+#undef SOME_FALSE
+#undef SOME_ZERO
+#undef SOME_ONE
+#undef SOME_TEN
+#undef SOME_ENUM_LITERAL
+#undef SOME_STRING

From 7e548af8b1527d2d04de1c12df9bf8afd1ad23ea Mon Sep 17 00:00:00 2001
From: Techatrix <techatrix@mailbox.org>
Date: Wed, 19 Feb 2025 09:03:56 +0100
Subject: [PATCH 2/4] std.Build.Step.ConfigHeader: allow using autoconf values
 multiple times

---
 lib/std/Build/Step/ConfigHeader.zig       | 17 +++++++++++------
 test/standalone/config_header/config.h    |  3 +++
 test/standalone/config_header/config.h.in |  3 +++
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/lib/std/Build/Step/ConfigHeader.zig b/lib/std/Build/Step/ConfigHeader.zig
index f474c38ff0..e1a7e9f63f 100644
--- a/lib/std/Build/Step/ConfigHeader.zig
+++ b/lib/std/Build/Step/ConfigHeader.zig
@@ -264,8 +264,11 @@ fn render_autoconf(
     values: std.StringArrayHashMap(Value),
     src_path: []const u8,
 ) !void {
-    var values_copy = try values.clone();
-    defer values_copy.deinit();
+    const build = step.owner;
+    const allocator = build.allocator;
+
+    var is_used: std.DynamicBitSetUnmanaged = try .initEmpty(allocator, values.count());
+    defer is_used.deinit(allocator);
 
     var any_errors = false;
     var line_index: u32 = 0;
@@ -284,18 +287,20 @@ fn render_autoconf(
             continue;
         }
         const name = it.rest();
-        const kv = values_copy.fetchSwapRemove(name) orelse {
+        const index = values.getIndex(name) orelse {
             try step.addError("{s}:{d}: error: unspecified config header value: '{s}'", .{
                 src_path, line_index + 1, name,
             });
             any_errors = true;
             continue;
         };
-        try renderValueC(output, name, kv.value);
+        is_used.set(index);
+        try renderValueC(output, name, values.values()[index]);
     }
 
-    for (values_copy.keys()) |name| {
-        try step.addError("{s}: error: config header value unused: '{s}'", .{ src_path, name });
+    var unused_value_it = is_used.iterator(.{ .kind = .unset });
+    while (unused_value_it.next()) |index| {
+        try step.addError("{s}: error: config header value unused: '{s}'", .{ src_path, values.keys()[index] });
         any_errors = true;
     }
 
diff --git a/test/standalone/config_header/config.h b/test/standalone/config_header/config.h
index 961fdc564f..aa9a9a707c 100644
--- a/test/standalone/config_header/config.h
+++ b/test/standalone/config_header/config.h
@@ -12,3 +12,6 @@ int foo();
 #define SOME_ENUM_LITERAL test
 #define SOME_STRING "test"
 
+// Used twice
+#define SOME_TRUE 1
+
diff --git a/test/standalone/config_header/config.h.in b/test/standalone/config_header/config.h.in
index 0bb37a419c..4858d08794 100644
--- a/test/standalone/config_header/config.h.in
+++ b/test/standalone/config_header/config.h.in
@@ -10,3 +10,6 @@ int foo();
 #undef SOME_TEN
 #undef SOME_ENUM_LITERAL
 #undef SOME_STRING
+
+// Used twice
+#undef SOME_TRUE

From 344db9e26bfb7a966cb99d73fa13c7d6845c2ce9 Mon Sep 17 00:00:00 2001
From: Techatrix <techatrix@mailbox.org>
Date: Wed, 19 Feb 2025 09:04:08 +0100
Subject: [PATCH 3/4] std.Build.Step.ConfigHeader: skip trailing whitespace in
 autoconf header

---
 lib/std/Build/Step/ConfigHeader.zig       | 2 +-
 test/standalone/config_header/build.zig   | 5 +++++
 test/standalone/config_header/config.h    | 5 +++++
 test/standalone/config_header/config.h.in | 5 +++++
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/std/Build/Step/ConfigHeader.zig b/lib/std/Build/Step/ConfigHeader.zig
index e1a7e9f63f..4174d398b4 100644
--- a/lib/std/Build/Step/ConfigHeader.zig
+++ b/lib/std/Build/Step/ConfigHeader.zig
@@ -286,7 +286,7 @@ fn render_autoconf(
             try output.appendSlice("\n");
             continue;
         }
-        const name = it.rest();
+        const name = it.next().?;
         const index = values.getIndex(name) orelse {
             try step.addError("{s}:{d}: error: unspecified config header value: '{s}'", .{
                 src_path, line_index + 1, name,
diff --git a/test/standalone/config_header/build.zig b/test/standalone/config_header/build.zig
index 0268b642a7..fba2613c5a 100644
--- a/test/standalone/config_header/build.zig
+++ b/test/standalone/config_header/build.zig
@@ -12,6 +12,11 @@ pub fn build(b: *std.Build) void {
             .SOME_TEN = 10,
             .SOME_ENUM_LITERAL = .@"test",
             .SOME_STRING = "test",
+
+            .PREFIX_SPACE = null,
+            .PREFIX_TAB = null,
+            .POSTFIX_SPACE = null,
+            .POSTFIX_TAB = null,
         },
     );
 
diff --git a/test/standalone/config_header/config.h b/test/standalone/config_header/config.h
index aa9a9a707c..298aeac344 100644
--- a/test/standalone/config_header/config.h
+++ b/test/standalone/config_header/config.h
@@ -15,3 +15,8 @@ int foo();
 // Used twice
 #define SOME_TRUE 1
 
+/* #undef PREFIX_SPACE */
+/* #undef PREFIX_TAB */
+/* #undef POSTFIX_SPACE */
+/* #undef POSTFIX_TAB */
+
diff --git a/test/standalone/config_header/config.h.in b/test/standalone/config_header/config.h.in
index 4858d08794..b4cf3a47ea 100644
--- a/test/standalone/config_header/config.h.in
+++ b/test/standalone/config_header/config.h.in
@@ -13,3 +13,8 @@ int foo();
 
 // Used twice
 #undef SOME_TRUE
+
+#undef PREFIX_SPACE
+#undef	PREFIX_TAB
+#undef POSTFIX_SPACE 
+#undef POSTFIX_TAB	

From c1c6f082961a2735ff3c91167f0e1bcfcfcc2010 Mon Sep 17 00:00:00 2001
From: Techatrix <techatrix@mailbox.org>
Date: Wed, 19 Feb 2025 09:33:56 +0100
Subject: [PATCH 4/4] std.Build.Step.ConfigHeader: permit inserting enum values

---
 lib/std/Build/Step/ConfigHeader.zig       | 2 +-
 test/standalone/config_header/build.zig   | 1 +
 test/standalone/config_header/config.h    | 1 +
 test/standalone/config_header/config.h.in | 1 +
 4 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/std/Build/Step/ConfigHeader.zig b/lib/std/Build/Step/ConfigHeader.zig
index 4174d398b4..72d5e99e3a 100644
--- a/lib/std/Build/Step/ConfigHeader.zig
+++ b/lib/std/Build/Step/ConfigHeader.zig
@@ -131,7 +131,7 @@ fn putValue(config_header: *ConfigHeader, field_name: []const u8, comptime T: ty
         .comptime_int => {
             try config_header.values.put(field_name, .{ .int = v });
         },
-        .enum_literal => {
+        .@"enum", .enum_literal => {
             try config_header.values.put(field_name, .{ .ident = @tagName(v) });
         },
         .optional => {
diff --git a/test/standalone/config_header/build.zig b/test/standalone/config_header/build.zig
index fba2613c5a..423e9d3823 100644
--- a/test/standalone/config_header/build.zig
+++ b/test/standalone/config_header/build.zig
@@ -10,6 +10,7 @@ pub fn build(b: *std.Build) void {
             .SOME_ZERO = 0,
             .SOME_ONE = 1,
             .SOME_TEN = 10,
+            .SOME_ENUM = @as(enum { foo, bar }, .foo),
             .SOME_ENUM_LITERAL = .@"test",
             .SOME_STRING = "test",
 
diff --git a/test/standalone/config_header/config.h b/test/standalone/config_header/config.h
index 298aeac344..22b5fb5697 100644
--- a/test/standalone/config_header/config.h
+++ b/test/standalone/config_header/config.h
@@ -9,6 +9,7 @@ int foo();
 #define SOME_ZERO 0
 #define SOME_ONE 1
 #define SOME_TEN 10
+#define SOME_ENUM foo
 #define SOME_ENUM_LITERAL test
 #define SOME_STRING "test"
 
diff --git a/test/standalone/config_header/config.h.in b/test/standalone/config_header/config.h.in
index b4cf3a47ea..c1b8fe7236 100644
--- a/test/standalone/config_header/config.h.in
+++ b/test/standalone/config_header/config.h.in
@@ -8,6 +8,7 @@ int foo();
 #undef SOME_ZERO
 #undef SOME_ONE
 #undef SOME_TEN
+#undef SOME_ENUM
 #undef SOME_ENUM_LITERAL
 #undef SOME_STRING