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fix(IWYU): force std:: or <> for max, min, copy #411

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Merged
aaronliu0130 merged 1 commit into from
Nov 27, 2025
Merged

fix(IWYU): force std:: or <> for max, min, copy #411

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14 changes: 10 additions & 4 deletions cpplint.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6837,9 +6837,6 @@ def ExpectingFunctionArgs(clean_lines, linenum):
(
"<algorithm>",
(
"copy",
"max",
"min",
"min_element",
"sort",
"transform",
Expand Down Expand Up @@ -6917,11 +6914,20 @@ def ExpectingFunctionArgs(clean_lines, linenum):
for _template in _templates
)

# Map is often overloaded. Only check, if it is fully qualified.
# Often overloaded, only check if fully qualified.
# Match 'std::map<type>(...)', but not 'map<type>(...)''
_re_pattern_headers_maybe_templates.append(
(re.compile(r"(std\b::\bmap\s*\<)|(^(std\b::\b)map\b\(\s*\<)"), "map<>", "<map>")
)
# Otherwise, causes false positives with direct initialization. ('int max(0);')
_re_pattern_headers_maybe_templates.extend(
(
re.compile(rf"std\b::\b{_template}\s*\([^\)]|\b{_template}\s*<.*?>\([^\)]"),
_template,
"<algorithm>",
)
for _template in ("copy", "max", "min")
)

# Other scripts may reach in and modify this pattern.
_re_pattern_templates: list[tuple[re.Pattern, str, str]] = []
Expand Down
1 change: 1 addition & 0 deletions cpplint_unittest.py
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Expand Up @@ -1227,6 +1227,7 @@ def testIncludeWhatYouUse(self):
""",
"Add #include <algorithm> for min [build/include_what_you_use] [4]",
)
self.TestIncludeWhatYouUse("int max(0), copy(max), min();", "")

Copilot AI Nov 27, 2025

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The test case verifies that false positives are suppressed, but there's no corresponding test to verify that legitimate uses of std::max(), std::min(), or std::copy() still trigger the include warning. Consider adding test cases like:

self.TestIncludeWhatYouUse("int x = std::max(a, b);", 
    "Add #include <algorithm> for max  [build/include_what_you_use] [4]")
self.TestIncludeWhatYouUse("std::copy(src.begin(), src.end(), dst.begin());",
    "Add #include <algorithm> for copy  [build/include_what_you_use] [4]")

This ensures the fix doesn't break detection of actual usage.

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@cclauss cclauss Nov 27, 2025

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How was this resolved? Do those tests already exist or are they not worth adding?

@aaronliu0130 aaronliu0130 Nov 27, 2025 •
edited
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Indeed, I didn't think they were worth adding—the max and copy regexes are the same as the already-tested one for min, and just like how regexes for max and copy weren't already there, throughout the unit tests each part of the relevant regex pattern is only tested once. Sorry for resolving without leaving this comment.

self.TestIncludeWhatYouUse(
'cout << "hello world" << endl;',
"Add #include <iostream> for cout [build/include_what_you_use] [4]",
Expand Down