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.
gcc/ChangeLog:
PR analyzer/125265
* params.opt: Define --param=analyzer-max-macro-alias-depth=.
gcc/c/ChangeLog:
PR analyzer/125265
* c-parser.cc: Follow macro alias to get the value for a named
constant.
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-v2" "refs/versioned_pull/226/2/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: 2026-10-03 10:35:40+00:00
Changes: 2 changed files, 23 additions, 3 deletions
Head revision: azoff/gcc ref pr/macro-aliases commit
8ac305a10b5089b38f36eca1d1bc66132e95545f
Base revision: gcc/gcc ref trunk commit
aaa0f6b1e87bc62ea15da6eab431af6dcebf6414 r17-3738-gaaa0f6b1e87bc6
Merge base: aaa0f6b1e87bc62ea15da6eab431af6dcebf6414
Requested Reviewers: dmalcolm
Changed files:
- M: gcc/c/c-parser.cc
- M: gcc/params.opt
gcc/c/c-parser.cc | 22 +++++++++++++++++++---
gcc/params.opt | 4 ++++
2 files changed, 23 insertions(+), 3 deletions(-)
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/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.
Range-diff against v1:
1: 650c07cdb2805 ! 1: 8ac305a10b508 analyzer: follow macro aliases for named
constant [PR125265]
@@ Commit message
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. It will follow up to 8 levels of macros
in
- order to reach the number.
+ 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
@@ Commit message
Regtested with arm-none-eabi (with newlib) on r17-3738-gaaa0f6b1e87bc6.
+ gcc/ChangeLog:
+
+ PR analyzer/125265
+ * params.opt: Define --param=analyzer-max-macro-alias-depth=.
+
gcc/c/ChangeLog:
PR analyzer/125265
- * c-parser.cc: Follow, up to eight, macro alias to get the
value
- for a named constant.
+ * c-parser.cc: Follow macro alias to get the value for a named
+ constant.
Signed-off-by: Torbjörn SVENSSON <[email protected]>
@@ gcc/c/c-parser.cc: private:
+ following the chain of aliases up to MAX_ALIAS_DEPTH deep. */
+ tree consider_macro (cpp_macro *macro, unsigned int depth = 0) const
{
-+ const unsigned int MAX_ALIAS_DEPTH = 8;
if (macro->paramc > 0)
return NULL_TREE;
- if (macro->kind != cmk_macro)
@@ gcc/c/c-parser.cc: private:
if (macro->count != 1)
return NULL_TREE;
@@ gcc/c/c-parser.cc: private:
+ if (tok.type == CPP_NAME)
+ {
+ /* Limit recursion. */
-+ if (depth >= MAX_ALIAS_DEPTH)
++ if (depth >= param_analyzer_max_macro_alias_depth)
+ return NULL_TREE;
+
+ cpp_hashnode *alias = tok.val.node.node;
@@ gcc/c/c-parser.cc: private:
return NULL_TREE;
cpp_reader *old_parse_in = parse_in;
+
+ ## 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
+ 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.
--
2.54.0
