Trac #33176: Fix a few cython "referenced before assignment" warnings

Our build displays several warnings like > warning: sage/libs/ntl/ntl_ZZ.pyx:274:23: local variable 'ans' referenced before assignment for variables that are passed by reference to a C function that overwrites them (meaning that there is no real bug). Here we fix a few easy ones by initializing the variable. URL: https://trac.sagemath.org/33176 Reported by: mjo Ticket author(s): Michael Orlitzky Reviewer(s): Markus Wageringel, Marc Mezzarobba
sagemath · Oct 30, 2022 · bff11ac · bff11ac
2 parents 89af346 + 93f2e90
commit bff11ac
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Showing 6 changed files with 7 additions and 7 deletions.
diff --git a/src/sage/libs/gap/element.pyx b/src/sage/libs/gap/element.pyx
@@ -264,7 +264,7 @@ cdef Obj make_gap_string(sage_string) except NULL:
     try:
         GAP_Enter()
         b = str_to_bytes(sage_string)
-        C_NEW_STRING(result, len(b), b)
+        result = MakeStringWithLen(b, len(b))
         return result
     finally:
         GAP_Leave()

diff --git a/src/sage/libs/gap/gap_includes.pxd b/src/sage/libs/gap/gap_includes.pxd
@@ -182,4 +182,4 @@ cdef extern from "gap/stringobj.h" nogil:
     bint IS_STRING(Obj obj)
     bint IsStringConv(Obj obj)
     Obj NEW_STRING(Int)
-    void C_NEW_STRING(Obj new_gap_string, int length, char* c_string)
+    Obj MakeStringWithLen(const char* buf, size_t len)
diff --git a/src/sage/libs/ntl/ntl_ZZ.pyx b/src/sage/libs/ntl/ntl_ZZ.pyx
@@ -281,7 +281,7 @@ cdef class ntl_ZZ():
 
         AUTHOR: David Harvey (2006-08-05)
         """
-        cdef int ans
+        cdef int ans = 0
         ZZ_conv_to_int(ans, self.x)
         return ans
 

diff --git a/src/sage/libs/ntl/ntl_ZZ_pX.pyx b/src/sage/libs/ntl/ntl_ZZ_pX.pyx
@@ -278,7 +278,7 @@ cdef class ntl_ZZ_pX():
         """
         self.c.restore_c()
         cdef ZZ_p_c r
-        cdef long l
+        cdef long l = 0
         sig_on()
         r = ZZ_pX_coeff( self.x, i)
         ZZ_conv_to_long(l, ZZ_p_rep(r))
@@ -1154,7 +1154,7 @@ cdef class ntl_ZZ_pX():
         ZZ_pX_Modulus_build(mod, modulus.x)
         cdef ntl_ZZ_pX mod_prime
         cdef ntl_ZZ_pContext_class ctx
-        cdef long mini, minval
+        cdef long mini = 0, minval = 0
         if Integer(modulus[0].lift()).valuation(p) == 1:
             eisenstein = True
             for c in modulus.list()[1:-1]:

diff --git a/src/sage/libs/singular/groebner_strategy.pyx b/src/sage/libs/singular/groebner_strategy.pyx
@@ -536,7 +536,7 @@ cdef class NCGroebnerStrategy(SageObject):
         if unlikely(self._parent._ring != currRing):
             rChangeCurrRing(self._parent._ring)
 
-        cdef int max_ind
+        cdef int max_ind = 0
         cdef poly *_p = redNF(p_Copy(p._poly, self._parent._ring), max_ind, 0, self._strat)
         if likely(_p!=NULL):
             _p = redtailBba(_p, max_ind, self._strat)

diff --git a/src/sage/matrix/matrix_modn_dense_template.pxi b/src/sage/matrix/matrix_modn_dense_template.pxi
@@ -278,7 +278,7 @@ cdef inline celement linbox_det(celement modulus, celement* entries, Py_ssize_t
     cdef ModField *F = new ModField(<long>modulus)
     cdef celement *cpy = linbox_copy(modulus, entries, n, n)
 
-    cdef celement d
+    cdef celement d = 0
     cdef size_t nbthreads
     nbthreads = Parallelism().get('linbox')