[llvm-bugs] [Bug 35001] New: uninitialized value false positive with identical conditions

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=35001

            Bug ID: 35001
           Summary: uninitialized value false positive with identical
                    conditions
           Product: clang
           Version: 5.0
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Static Analyzer
          Assignee: dcoughlin at apple.com
          Reporter: ssapa at arista.com
                CC: llvm-bugs at lists.llvm.org

clang version 5.0.0 (trunk)
Target: i686-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/i686-redhat-linux/5.4.0
Found candidate GCC installation: /usr/lib/gcc/i686-redhat-linux/5.4.0
Selected GCC installation: /usr/bin/../lib/gcc/i686-redhat-linux/5.4.0
Candidate multilib: .;@m32
Selected multilib: .;@m32


This snippet (foo.cpp) makes the analyzer to warn about an uninitialized value:

#include <iostream>

void run( double limit ) {
   int a;

   if ( limit > 0 ) {
      a = 1;
   }
   if ( limit > 0 ) {
      std::cout << a;
   }
}

clang++ --analyze -Xanalyzer -analyzer-output=text -std=c++11 foo.cpp

foo.cpp:10:7: warning: 1st function call argument is an uninitialized value
      std::cout << a;
      ^            ~
foo.cpp:4:4: note: 'a' declared without an initial value
   int a;
   ^~~~~
foo.cpp:6:4: note: Taking false branch
   if ( limit > 0 ) {
   ^
foo.cpp:9:4: note: Taking true branch
   if ( limit > 0 ) {
   ^
foo.cpp:10:7: note: 1st function call argument is an uninitialized value
      std::cout << a;
      ^            ~
1 warning generated.

Making the value type an 'int' does not show the same symptoms, ie. void run(
int limi )

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