From: Torbjörn SVENSSON <[email protected]>
Newlib, picolibc, and probably other libc implementations, use
#define O_CREAT _FCREAT
#define O_TRUNC _FTRUNC
#define O_EXCL _FEXCL
In r17-177-g9a5f89005dc49d, support was added to identify redundant
flags, but the implementation requires that the value of the macros
O_CREAT, O_EXCL, O_RDWR to be a number. This patch extends the support
to also allow macro aliases. The maximum followed levels is by default
8 levels, but can be tuned via --param=analyzer-max-macro-alias-depth=n.
This change fixes
FAIL: gcc.dg/analyzer/mkostemp-1.c (test for warnings, line 109)
FAIL: gcc.dg/analyzer/mkostemp-1.c (test for warnings, line 115)
FAIL: gcc.dg/analyzer/mkostemps-1.c (test for warnings, line 115)
FAIL: gcc.dg/analyzer/mkostemps-1.c (test for warnings, line 121)
Regtested with arm-none-eabi (with newlib) on r17-3738-gaaa0f6b1e87bc6.
PR analyzer/125265
gcc/ChangeLog:
* doc/params.texi (analyzer-max-macro-alias-depth): Document.
* params.opt (-param=analyzer-max-macro-alias-depth=): New.
gcc/c/ChangeLog:
* c-parser.cc: Follow macro alias to get the value for a named
constant.
gcc/testsuite/ChangeLog:
* gcc.dg/analyzer/named-constants-via-macros-alias.c: New test.
Signed-off-by: Torbjörn SVENSSON <[email protected]>
---
Ok for trunk?
I'm unsure if this should also go into releases/gcc-16, WDYT?
--
This is a forge pull request published on the gcc-patches mailing list mailing
list
as requested by Torbjörn Svensson via Sourceware Forge
<[email protected]>.
Forge discussion: https://forge.sourceware.org/gcc/gcc/pulls/226
Get it locally using:
```
git fetch forge-upstream "+refs/versioned_pull/226/*:refs/versioned_pull/226/*"
git switch -c "pr-226-v3" "refs/versioned_pull/226/3/head"
```
Or, download the patch at: https://forge.sourceware.org/gcc/gcc/pulls/226.diff
Created on: 2026-08-31 06:26:23+00:00
Latest update: 2026-10-06 16:50:51+00:00
Changes: 4 changed files, 42 additions, 3 deletions
Head revision: azoff/gcc ref pr/macro-aliases commit
f5ef3a0b9d507945c14f74d41fb711dd74f7416a
Base revision: gcc/gcc ref trunk commit
aaa0f6b1e87bc62ea15da6eab431af6dcebf6414 r17-3738-gaaa0f6b1e87bc6
Merge base: aaa0f6b1e87bc62ea15da6eab431af6dcebf6414
Requested Reviewers: dmalcolm
Changed files:
- A: gcc/testsuite/gcc.dg/analyzer/named-constants-via-macros-alias.c
- M: gcc/c/c-parser.cc
- M: gcc/doc/params.texi
- M: gcc/params.opt
gcc/c/c-parser.cc | 22 ++++++++++++++++---
gcc/doc/params.texi | 5 +++++
gcc/params.opt | 4 ++++
.../named-constants-via-macros-alias.c | 14 ++++++++++++
4 files changed, 42 insertions(+), 3 deletions(-)
create mode 100644
gcc/testsuite/gcc.dg/analyzer/named-constants-via-macros-alias.c
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 9dc5ba1e3a13f..e03c06da9a233 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -2019,8 +2019,11 @@ private:
#define NAME 42
and other bases but not negative numbers, parentheses or e.g.
#define NAME 1 << 7
- as doing so would require a parser. */
- tree consider_macro (cpp_macro *macro) const
+ as doing so would require a parser.
+ Also handle the case where MACRO's definition is a single identifier
+ that is itself a macro name (e.g. "#define O_CREAT _FCREAT"), by
+ following the chain of aliases up to MAX_ALIAS_DEPTH deep. */
+ tree consider_macro (cpp_macro *macro, unsigned int depth = 0) const
{
if (macro->paramc > 0)
return NULL_TREE;
@@ -2029,7 +2032,20 @@ private:
if (macro->count != 1)
return NULL_TREE;
const cpp_token &tok = macro->exp.tokens[0];
- if (tok.type != CPP_NUMBER)
+ if (tok.type == CPP_NAME)
+ {
+ /* Limit recursion. */
+ if (depth >= param_analyzer_max_macro_alias_depth)
+ return NULL_TREE;
+
+ cpp_hashnode *alias = tok.val.node.node;
+ if (cpp_macro_p (alias))
+ return consider_macro (alias->value.macro, depth + 1);
+
+ /* Not a simple alias. */
+ return NULL_TREE;
+ }
+ else if (tok.type != CPP_NUMBER)
return NULL_TREE;
cpp_reader *old_parse_in = parse_in;
diff --git a/gcc/doc/params.texi b/gcc/doc/params.texi
index e69be2d2923e4..ba46391d00c35 100644
--- a/gcc/doc/params.texi
+++ b/gcc/doc/params.texi
@@ -1884,6 +1884,11 @@ the value as unknown.
The maximum number of infeasible edges to reject before declaring
a diagnostic as infeasible.
+@paindex analyzer-max-macro-alias-depth
+@item analyzer-max-macro-alias-depth
+The maximum number of macro aliases to follow when resolving named constants
+in the analyzer.
+
@paindex gimple-fe-computed-hot-bb-threshold
@item gimple-fe-computed-hot-bb-threshold
The number of executions of a basic block that is considered hot.
diff --git a/gcc/params.opt b/gcc/params.opt
index 0c6a3e5145749..6e3458ccb955e 100644
--- a/gcc/params.opt
+++ b/gcc/params.opt
@@ -30,6 +30,10 @@ Loops iterating at least selected number of iterations get
loop alignment.
Common Joined UInteger Var(param_align_threshold) Init(100) IntegerRange(1,
65536) Param Optimization
Select fraction of the maximal frequency of executions of basic block in
function given basic block get alignment.
+-param=analyzer-max-macro-alias-depth=
+Common Joined UInteger Var(param_analyzer_max_macro_alias_depth) Init(8)
IntegerRange(0, 255)
+Maximum number of macro aliases to follow when resolving named constants in
the analyzer; zero disables alias following.
+
-param=asan-globals=
Common Joined UInteger Var(param_asan_globals) Init(1) IntegerRange(0, 1) Param
Enable asan globals protection.
diff --git a/gcc/testsuite/gcc.dg/analyzer/named-constants-via-macros-alias.c
b/gcc/testsuite/gcc.dg/analyzer/named-constants-via-macros-alias.c
new file mode 100644
index 0000000000000..d74eb12958d94
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/named-constants-via-macros-alias.c
@@ -0,0 +1,14 @@
+/* { dg-additional-options "--param=analyzer-max-macro-alias-depth=1" } */
+
+#include "analyzer-decls.h"
+
+#define O_CREAT 42 /* 0 aliases. */
+#define O_EXCL O_CREAT /* 1 alias. */
+#define O_RDWR O_EXCL /* 2 aliases. */
+
+void test_macro_aliases (void)
+{
+ __analyzer_dump_named_constant ("O_CREAT"); /* { dg-warning "named constant
'O_CREAT' has value '42'" } */
+ __analyzer_dump_named_constant ("O_EXCL"); /* { dg-warning "named constant
'O_EXCL' has value '42'" } */
+ __analyzer_dump_named_constant ("O_RDWR"); /* { dg-warning "named constant
'O_RDWR' has unknown value" } */
+}
Range-diff against v2:
1: 8ac305a10b508 ! 1: f5ef3a0b9d507 analyzer: follow macro aliases for named
constant [PR125265]
@@ Commit message
Regtested with arm-none-eabi (with newlib) on r17-3738-gaaa0f6b1e87bc6.
+ PR analyzer/125265
+
gcc/ChangeLog:
- PR analyzer/125265
- * params.opt: Define --param=analyzer-max-macro-alias-depth=.
+ * doc/params.texi (analyzer-max-macro-alias-depth): Document.
+ * params.opt (-param=analyzer-max-macro-alias-depth=): New.
gcc/c/ChangeLog:
- PR analyzer/125265
* c-parser.cc: Follow macro alias to get the value for a named
constant.
+ gcc/testsuite/ChangeLog:
+
+ * gcc.dg/analyzer/named-constants-via-macros-alias.c: New test.
+
Signed-off-by: Torbjörn SVENSSON <[email protected]>
## gcc/c/c-parser.cc ##
@@ gcc/c/c-parser.cc: private:
cpp_reader *old_parse_in = parse_in;
+ ## gcc/doc/params.texi ##
+@@ gcc/doc/params.texi: the value as unknown.
+ The maximum number of infeasible edges to reject before declaring
+ a diagnostic as infeasible.
+
++@paindex analyzer-max-macro-alias-depth
++@item analyzer-max-macro-alias-depth
++The maximum number of macro aliases to follow when resolving named
constants
++in the analyzer.
++
+ @paindex gimple-fe-computed-hot-bb-threshold
+ @item gimple-fe-computed-hot-bb-threshold
+ The number of executions of a basic block that is considered hot.
+
## gcc/params.opt ##
@@ gcc/params.opt: Loops iterating at least selected number of iterations
get loop alignment.
Common Joined UInteger Var(param_align_threshold) Init(100)
IntegerRange(1, 65536) Param Optimization
@@ gcc/params.opt: Loops iterating at least selected number of iterations
get loop
-param=asan-globals=
Common Joined UInteger Var(param_asan_globals) Init(1) IntegerRange(0, 1)
Param
Enable asan globals protection.
+
+ ## gcc/testsuite/gcc.dg/analyzer/named-constants-via-macros-alias.c (new)
##
+@@
++/* { dg-additional-options "--param=analyzer-max-macro-alias-depth=1" } */
++
++#include "analyzer-decls.h"
++
++#define O_CREAT 42 /* 0 aliases. */
++#define O_EXCL O_CREAT /* 1 alias. */
++#define O_RDWR O_EXCL /* 2 aliases. */
++
++void test_macro_aliases (void)
++{
++ __analyzer_dump_named_constant ("O_CREAT"); /* { dg-warning "named
constant 'O_CREAT' has value '42'" } */
++ __analyzer_dump_named_constant ("O_EXCL"); /* { dg-warning "named
constant 'O_EXCL' has value '42'" } */
++ __analyzer_dump_named_constant ("O_RDWR"); /* { dg-warning "named
constant 'O_RDWR' has unknown value" } */
++}
--
2.54.0
