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synqt.cpp: scan for and reject #pragma once

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In 2022¹, we gave ourselves the rule to allow #pragma once only in
non-installed headers (examples, tools, snippets, ...), because the
same installed header may reside in different places in the filesystem
and #pragma once would treat these as separate headers, causing
multiple-definition errors.

Recently, the question came up: "What constitutes a public header?"

Non-_p.h headers in e.g. src/plugins/ muddy the waters here a
bit. Since #pragma once is forbidden in installed headers, I had the
idea to use it to indicate non-installed headers. This patch enables
use of #pragma once as a static assertion to that effect, should we so
choose.

¹ https://lists.qt-project.org/pipermail/development/2022-October/043121.html

Pick-to: 6.6 6.5
Fixes: QTBUG-122813
Change-Id: I3b5beef72e154cf5bf1ccd4b6f02df9680609e43
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by:  Alexey Edelev <alexey.edelev@qt.io>
(cherry picked from commit 1c8884fc277c5916a420a3c14de68547a391f9fc)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Marc Mutz 2024-02-28 14:32:26 +01:00 committed by Qt Cherry-pick Bot
parent a05aa394b9
commit 12bf8fd618
1 changed files with 15 additions and 3 deletions
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18
src/tools/syncqt/main.cpp
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@ -43,9 +43,10 @@ enum HeaderChecks {
PrivateHeaderChecks = 2, /* Checks if the public header includes a private header */
IncludeChecks = 4, /* Checks if the real header file but not an alias is included */
WeMeantItChecks = 8, /* Checks if private header files contains 'We meant it' disclaimer */
CriticalChecks = PrivateHeaderChecks, /* Checks that lead to the fatal error of the sync
process */
AllChecks = NamespaceChecks | PrivateHeaderChecks | IncludeChecks | WeMeantItChecks,
PragmaOnceChecks = 16,
/* Checks that lead to the fatal error of the sync process: */
CriticalChecks = PrivateHeaderChecks | PragmaOnceChecks,
AllChecks = NamespaceChecks | CriticalChecks | IncludeChecks | WeMeantItChecks,
};
constexpr int LinkerScriptCommentAlignment = 55;
@ -1084,6 +1085,9 @@ public:
static const std::regex MacroRegex("^\\s*#.*");
// The regex's bellow check line for known pragmas:
//
// - 'once' is not allowed in installed headers, so error out.
//
// - 'qt_sync_skip_header_check' avoid any header checks.
//
// - 'qt_sync_stop_processing' stops the header proccesing from a moment when pragma is
@ -1111,6 +1115,7 @@ public:
//
// - 'qt_no_master_include' indicates that syncqt should avoid including this header
// files into the module master header file.
static const std::regex OnceRegex(R"(^#\s*pragma\s+once$)");
static const std::regex SkipHeaderCheckRegex("^#\\s*pragma qt_sync_skip_header_check$");
static const std::regex StopProcessingRegex("^#\\s*pragma qt_sync_stop_processing$");
static const std::regex SuspendProcessingRegex("^#\\s*pragma qt_sync_suspend_processing$");
@ -1298,6 +1303,13 @@ public:
} else if (std::regex_match(buffer, match, DeprecatesPragmaRegex)) {
m_deprecatedHeaders[match[1].str()] =
m_commandLineArgs->moduleName() + '/' + m_currentFilename;
} else if (std::regex_match(buffer, OnceRegex)) {
if (!(skipChecks & PragmaOnceChecks)) {
faults |= PragmaOnceChecks;
error() << "\"#pragma once\" is not allowed in installed header files: "
"https://lists.qt-project.org/pipermail/development/2022-October/043121.html"
<< std::endl;
}
} else if (std::regex_match(buffer, match, IncludeRegex) && !isSuspended) {
if (!(skipChecks & IncludeChecks)) {
std::string includedHeader = match[1].str();