Pylauncher does not correctly detect a BOM when searching for the shebang

[chris-eibl]

Bug report

Bug description:

This is due to

cpython/PC/launcher2.c

Lines 1080 to 1081 in 475f933

	if (bytesRead > 3 && *b == 0xEF) {
	if (*++b == 0xBB && *++b == 0xBF) {

for wich clang-cl creates the following warnings:

1>..\PC\launcher2.c(1080,29): warning : result of comparison of constant 239 with expression of type 'char' is always false [-Wtautological-constant-out-of-range-compare]
1>..\PC\launcher2.c(1081,34): warning : result of comparison of constant 191 with expression of type 'char' is always false [-Wtautological-constant-out-of-range-compare]
1>..\PC\launcher2.c(1081,18): warning : result of comparison of constant 187 with expression of type 'char' is always false [-Wtautological-constant-out-of-range-compare]

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

Linked PRs

• gh-131020: Pylauncher does not correctly detect a BOM when searching for the shebang #131021
• [3.13] gh-131020: py.exe launcher does not correctly detect a BOM when searching for the shebang (GH-131021) #131047
• [3.12] gh-131020: py.exe launcher does not correctly detect a BOM when searching for the shebang (GH-131021) #131048

[StanFromIreland]

Duplicate: #99620

[picnixz]

Please use the original issue for the PR but post the issue description out there as well as clang-cl was not available at that time. TiA.

I'll close this one as a duplicate

[StanFromIreland]

@picnixz Why not close the old one instead, there was no useful discussion there?

[picnixz]

There is a useful discussion in the sense that we have multiple reproducers. And it's because it doesn't usually make sense to always move the discussion elsewhere unless the old discussion needs to be terminated.

Also I think it's a matter of who has reported what and when. Historically it's nice to know that the issue is not new as well.

I have once closed an old duplicate because the new issue had new insights and different suggestions. But Serhiy was surprised by this choice and told me that the convention was to keep old ones.

[picnixz]

Reopening as it appeared that this wasn't true duplicate although the errors were similar.