https://github.com/vbvictor updated
https://github.com/llvm/llvm-project/pull/144274
>From 98fc81696400be2ea990d867375530ef3f544b82 Mon Sep 17 00:00:00 2001
From: Victor Baranov <bar.victor.2...@gmail.com>
Date: Sun, 15 Jun 2025 22:20:54 +0300
Subject: [PATCH 1/2] [Clang] Fix '-Wformat-overflow' FP when floats had
field-width and plus prefix
---
clang/docs/ReleaseNotes.rst | 3 +++
clang/lib/Sema/SemaChecking.cpp | 5 ++++-
clang/test/Sema/warn-format-overflow-truncation.c | 10 ++++++++++
3 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 33ee8a53b5f37..63a530f6ed622 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -629,6 +629,9 @@ Improvements to Clang's diagnostics
#GH69470, #GH59391, #GH58172, #GH46215, #GH45915, #GH45891, #GH44490,
#GH36703, #GH32903, #GH23312, #GH69874.
+- Fixed false positives in ``-Wformat-truncation`` and ``-Wformat-overflow``
+ diagnostics when floating-point numbers had both width field and plus or
space
+ prefix specified.
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 69276ce418fa6..8501ce681e903 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1012,7 +1012,10 @@ class EstimateSizeFormatHandler
break;
}
- Size += FS.hasPlusPrefix() || FS.hasSpacePrefix();
+ // If field width is specified, the sign/space is already accounted for
+ // within the field width, so no additional size is needed.
+ if ((FS.hasPlusPrefix() || FS.hasSpacePrefix()) && FieldWidth == 0)
+ Size += 1;
if (FS.hasAlternativeForm()) {
switch (FS.getConversionSpecifier().getKind()) {
diff --git a/clang/test/Sema/warn-format-overflow-truncation.c
b/clang/test/Sema/warn-format-overflow-truncation.c
index c64a1ed8aaa05..5fa770d3d3c51 100644
--- a/clang/test/Sema/warn-format-overflow-truncation.c
+++ b/clang/test/Sema/warn-format-overflow-truncation.c
@@ -43,6 +43,11 @@ void call_snprintf(double d, int n, int *ptr) {
__builtin_snprintf(node_name, sizeof(node_name), "%pOFn", ptr); //
nonkprintf-warning {{'snprintf' will always be truncated; specified size is 6,
but format string expands to at least 7}}
__builtin_snprintf(node_name, sizeof(node_name), "12345%pOFn", ptr); //
nonkprintf-warning {{'snprintf' will always be truncated; specified size is 6,
but format string expands to at least 12}}
__builtin_snprintf(node_name, sizeof(node_name), "123456%pOFn", ptr); //
nonkprintf-warning {{'snprintf' will always be truncated; specified size is 6,
but format string expands to at least 13}}
+ __builtin_snprintf(buf, 6, "%5.1f", 9.f);
+ __builtin_snprintf(buf, 6, "%+5.1f", 9.f);
+ __builtin_snprintf(buf, 6, "% 5.1f", 9.f);
+ __builtin_snprintf(buf, 6, "%+6.1f", 9.f); // kprintf-warning {{'snprintf'
will always be truncated; specified size is 6, but format string expands to at
least 7}}
+ __builtin_snprintf(buf, 6, "% 6.1f", 9.f); // kprintf-warning {{'snprintf'
will always be truncated; specified size is 6, but format string expands to at
least 7}}
}
void call_vsnprintf(void) {
@@ -153,4 +158,9 @@ void call_sprintf(void) {
sprintf(buf, "%+.3f", 9.f); // kprintf-warning {{'sprintf' will always
overflow; destination buffer has size 6, but format string expands to at least
7}}
sprintf(buf, "%.0e", 9.f);
sprintf(buf, "5%.1e", 9.f); // kprintf-warning {{'sprintf' will always
overflow; destination buffer has size 6, but format string expands to at least
8}}
+ sprintf(buf, "%5.1f", 9.f);
+ sprintf(buf, "%+5.1f", 9.f);
+ sprintf(buf, "% 5.1f", 9.f);
+ sprintf(buf, "%+6.1f", 9.f); // kprintf-warning {{'sprintf' will always
overflow; destination buffer has size 6, but format string expands to at least
7}}
+ sprintf(buf, "% 6.1f", 9.f); // kprintf-warning {{'sprintf' will always
overflow; destination buffer has size 6, but format string expands to at least
7}}
}
>From ab5d45bd83bcd8bf5c5e5703df71710e4a554878 Mon Sep 17 00:00:00 2001
From: Baranov Victor <bar.victor.2...@gmail.com>
Date: Mon, 16 Jun 2025 21:01:01 +0300
Subject: [PATCH 2/2] add gh issue reference to clang/docs/ReleaseNotes.rst
Co-authored-by: Aaron Ballman <aa...@aaronballman.com>
---
clang/docs/ReleaseNotes.rst | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 63a530f6ed622..741e39471569f 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -631,7 +631,7 @@ Improvements to Clang's diagnostics
- Fixed false positives in ``-Wformat-truncation`` and ``-Wformat-overflow``
diagnostics when floating-point numbers had both width field and plus or
space
- prefix specified.
+ prefix specified. (#GH143951)
Improvements to Clang's time-trace
----------------------------------
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