[libc-commits] [libc] [libc] Elide extra space in hdrgen function declarations (PR #127287)

[Roland McGrath via libc-commits]

https://github.com/frobtech updated https://github.com/llvm/llvm-project/pull/127287

>From aa0af95d4bdfdf97ec1372a2a1eb4f582f76745d Mon Sep 17 00:00:00 2001
From: Roland McGrath <mcgrathr at google.com>
Date: Thu, 13 Feb 2025 23:33:37 -0800
Subject: [PATCH 1/2] [libc] Elide extra space in hdrgen function declarations

When the return type's rendering already doesn't end with an
identifier character, such as when it's `T *`, then idiomatic
syntax does not include a space before the `(` and arguments.
---
 libc/utils/hdrgen/function.py                         | 5 ++++-
 libc/utils/hdrgen/tests/expected_output/subdir/test.h | 2 ++
 libc/utils/hdrgen/tests/input/subdir/test.yaml        | 3 +++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/libc/utils/hdrgen/function.py b/libc/utils/hdrgen/function.py
index bccd2c2caa2f5..24b28f7e3c7ff 100644
--- a/libc/utils/hdrgen/function.py
+++ b/libc/utils/hdrgen/function.py
@@ -81,4 +81,7 @@ def collapse(type_string):
     def __str__(self):
         attrs_str = "".join(f"{attr} " for attr in self.attributes)
         arguments_str = ", ".join(self.arguments) if self.arguments else "void"
-        return attrs_str + f"{self.return_type} {self.name}({arguments_str})"
+        type_str = str(self.return_type)
+        if type_str[-1].isalnum() or type_str[-1] == "_":
+            type_str += " "
+        return attrs_str + type_str + self.name + "(" + arguments_str + ")"
diff --git a/libc/utils/hdrgen/tests/expected_output/subdir/test.h b/libc/utils/hdrgen/tests/expected_output/subdir/test.h
index e968f92bf4e6d..20bab502e6821 100644
--- a/libc/utils/hdrgen/tests/expected_output/subdir/test.h
+++ b/libc/utils/hdrgen/tests/expected_output/subdir/test.h
@@ -19,6 +19,8 @@ type_a func(type_b) __NOEXCEPT;
 
 void gnufunc(type_a) __NOEXCEPT;
 
+int *ptrfunc(void) __NOEXCEPT;
+
 __END_C_DECLS
 
 #endif // LLVM_LIBC_SUBDIR_TEST_H
diff --git a/libc/utils/hdrgen/tests/input/subdir/test.yaml b/libc/utils/hdrgen/tests/input/subdir/test.yaml
index f325363e09cde..5bc8b29e334f8 100644
--- a/libc/utils/hdrgen/tests/input/subdir/test.yaml
+++ b/libc/utils/hdrgen/tests/input/subdir/test.yaml
@@ -12,3 +12,6 @@ functions:
       - type: type_a
     standards:
       - gnu
+  - name: ptrfunc
+    return_type: int *
+    arguments: []

>From eed21f5fa1a9407dd89322b49503a58caf42f79a Mon Sep 17 00:00:00 2001
From: Roland McGrath <mcgrathr at google.com>
Date: Fri, 14 Feb 2025 17:09:07 -0800
Subject: [PATCH 2/2] Add comment

---
 libc/utils/hdrgen/function.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libc/utils/hdrgen/function.py b/libc/utils/hdrgen/function.py
index 24b28f7e3c7ff..28af05f78d897 100644
--- a/libc/utils/hdrgen/function.py
+++ b/libc/utils/hdrgen/function.py
@@ -81,6 +81,11 @@ def collapse(type_string):
     def __str__(self):
         attrs_str = "".join(f"{attr} " for attr in self.attributes)
         arguments_str = ", ".join(self.arguments) if self.arguments else "void"
+        # The rendering of the return type may look like `int` or it may look
+        # like `int *` (and other examples).  For `int`, a space is always
+        # needed to separate the tokens.  For `int *`, no whitespace matters to
+        # the syntax one way or the other, but an extra space between `*` and
+        # the function identifier is not the canonical style.
         type_str = str(self.return_type)
         if type_str[-1].isalnum() or type_str[-1] == "_":
             type_str += " "