| Summary: | [3.4 Regression] Missing uninitialized warning with dead code (pure/const functions) | ||
|---|---|---|---|
| Product: | gcc | Reporter: | Axel Andersson <axel> |
| Component: | middle-end | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED FIXED | ||
| Severity: | minor | CC: | gcc-bugs |
| Priority: | P3 | Keywords: | diagnostic |
| Version: | 3.4.2 | ||
| Target Milestone: | 4.1.0 | ||
| Host: | Target: | ||
| Build: | Known to work: | 2.95.3 4.0.0 | |
| Known to fail: | 3.4.0 3.3.3 | Last reconfirmed: | 2005-10-02 19:47:53 |
| Bug Depends on: | |||
| Bug Blocks: | 24639 | ||
Confirmed as a regression but was fixed already on the mainline. On the mainline get a warning about all four including a so that part is not a regression. I don't know if we can do anything about it as we remove the call to bar as it is a pure/const function and we don't use the result of the function at all. If you used the result of the function call, you would get a warning about all four on 3.4 including a which does not exist on before 3.4.0. No plans exist to address these issues in the 3.x series. It works as expected in GCC 4.1. |
Consider the following code snippet: $ cat testcase.c int bar(int n) { return n + 1; } int main(void) { int a = bar(a); int b, c, d; b = bar(b); (void) bar(c); return bar(d); } Both a, b, c and d are used before they are initialized. However, we only get a warning from d in gcc 3.3/3.4. $ gcc -O2 -Wuninitialized testcase.c testcase.c: In function `main': testcase.c:8: warning: `d' might be used uninitialized in this function Tested on: gcc version 3.3 20030304 (Apple Computer, Inc. build 1640) gcc version 3.4.2 [FreeBSD] 20040728 In gcc 2.95, we get a warning from b, c and d, but not a. $ gcc -O2 -Wuninitialized testcase.c testcase.c: In function `main': testcase.c:8: warning: `b' might be used uninitialized in this function testcase.c:8: warning: `c' might be used uninitialized in this function testcase.c:8: warning: `d' might be used uninitialized in this function Tested on: gcc version 2.95.3 20010125 (prerelease) (OpenBSD)