[Bug 1249505] [NEW] clang fails to report uninitialized local variable

[Kevin Grittner]

Public bug reported:

$ lsb_release -rd
Description: Ubuntu 12.10
Release: 12.10

$ apt-cache policy clang
clang:
  Installed: 3.0-6ubuntu3
  Candidate: 3.0-6ubuntu3
  Version table:
 *** 3.0-6ubuntu3 0
        500 http://us.archive.ubuntu.com/ubuntu/ quantal/universe amd64 Packages
        100 /var/lib/dpkg/status

With source file named warning_test.c in the current working directory,
containing this:


int warning_test(int a);
int warning_test(int a)
{
	int			result;

	if (a == 1)
		result = 1;

	return result;
}


... I compiled with this command line:

clang -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-
after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-
security -fno-strict-aliasing -fwrapv -g -D_GNU_SOURCE -c -o
warning_test.o warning_test.c -MMD -MP

I expected:

warning_test.c:9:9: warning: variable 'result' is uninitialized when used here [-Wuninitialized]
        return result;
               ^~~~~~
warning_test.c:4:14: note: initialize the variable 'result' to silence this warning
        int                     result;
                                      ^
                                       = 0
1 warning generated.

I got a clean compile (no warnings).

** Affects: gcc-defaults (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1249505

Title:
  clang fails to report uninitialized local variable

Status in “gcc-defaults” package in Ubuntu:
  New

Bug description:
  $ lsb_release -rd
  Description: Ubuntu 12.10
  Release: 12.10

  $ apt-cache policy clang
  clang:
    Installed: 3.0-6ubuntu3
    Candidate: 3.0-6ubuntu3
    Version table:
   *** 3.0-6ubuntu3 0
          500 http://us.archive.ubuntu.com/ubuntu/ quantal/universe amd64 Packages
          100 /var/lib/dpkg/status

  With source file named warning_test.c in the current working
  directory, containing this:

  
  int warning_test(int a);
  int warning_test(int a)
  {
  	int			result;

  	if (a == 1)
  		result = 1;

  	return result;
  }

  
  ... I compiled with this command line:

  clang -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-
  after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-
  security -fno-strict-aliasing -fwrapv -g -D_GNU_SOURCE -c -o
  warning_test.o warning_test.c -MMD -MP

  I expected:

  warning_test.c:9:9: warning: variable 'result' is uninitialized when used here [-Wuninitialized]
          return result;
                 ^~~~~~
  warning_test.c:4:14: note: initialize the variable 'result' to silence this warning
          int                     result;
                                        ^
                                         = 0
  1 warning generated.

  I got a clean compile (no warnings).

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