From: Teemu Murtola <teemu.murtola@gmail.com>
Date: Sun, 10 Aug 2014 04:17:20 +0000 (+0300)
Subject: Make vec.h const-correct with both C and C++
X-Git-Url: http://biod.pnpi.spb.ru/gitweb/?a=commitdiff_plain;h=6f2a3703ee50529969a655aeec8bffd94c5dc8ab;p=alexxy%2Fgromacs.git

Make vec.h const-correct with both C and C++

C and C++ have different semantics for const if a function parameter has
multiple indirections (e.g., a double pointer or a 2D array).  If such a
parameter is not modified by the function, it is tricky to write
const-correct code using such functions:
 - If the parameter is declared const, then C will give a warning if a
   non-const value is passed.
 - If the parameter is not declared const, then C++ will give an error
   if a const value is passed.
Added a macro that allows using a single declaration in vec.h for
functions that take matrix values as input parameters, and still making
it possible to pass both non-const and const values to such parameters
in both C and C++.

Change-Id: Ifca3ff6842489c3a1040a8261ba429d96409fc21
---

diff --git a/src/gromacs/math/vec.h b/src/gromacs/math/vec.h
index f750f8fc02..307a9db118 100644
--- a/src/gromacs/math/vec.h
+++ b/src/gromacs/math/vec.h
@@ -331,7 +331,7 @@ static gmx_inline void copy_rvec(const rvec a, rvec b)
     b[ZZ] = a[ZZ];
 }
 
-static gmx_inline void copy_rvecn(rvec *a, rvec *b, int startn, int endn)
+static gmx_inline void copy_rvecn(gmx_cxx_const rvec *a, rvec *b, int startn, int endn)
 {
     int i;
     for (i = startn; i < endn; i++)
@@ -369,7 +369,7 @@ static gmx_inline void ivec_sub(const ivec a, const ivec b, ivec c)
     c[ZZ] = z;
 }
 
-static gmx_inline void copy_mat(matrix a, matrix b)
+static gmx_inline void copy_mat(gmx_cxx_const matrix a, matrix b)
 {
     copy_rvec(a[XX], b[XX]);
     copy_rvec(a[YY], b[YY]);
@@ -619,7 +619,7 @@ gmx_angle(const rvec a, const rvec b)
     return atan2(wlen, s);
 }
 
-static gmx_inline void mmul_ur0(matrix a, matrix b, matrix dest)
+static gmx_inline void mmul_ur0(gmx_cxx_const matrix a, gmx_cxx_const matrix b, matrix dest)
 {
     dest[XX][XX] = a[XX][XX]*b[XX][XX];
     dest[XX][YY] = 0.0;
@@ -632,7 +632,7 @@ static gmx_inline void mmul_ur0(matrix a, matrix b, matrix dest)
     dest[ZZ][ZZ] =                                        a[ZZ][ZZ]*b[ZZ][ZZ];
 }
 
-static gmx_inline void mmul(matrix a, matrix b, matrix dest)
+static gmx_inline void mmul(gmx_cxx_const matrix a, gmx_cxx_const matrix b, matrix dest)
 {
     dest[XX][XX] = a[XX][XX]*b[XX][XX]+a[XX][YY]*b[YY][XX]+a[XX][ZZ]*b[ZZ][XX];
     dest[YY][XX] = a[YY][XX]*b[XX][XX]+a[YY][YY]*b[YY][XX]+a[YY][ZZ]*b[ZZ][XX];
@@ -645,7 +645,7 @@ static gmx_inline void mmul(matrix a, matrix b, matrix dest)
     dest[ZZ][ZZ] = a[ZZ][XX]*b[XX][ZZ]+a[ZZ][YY]*b[YY][ZZ]+a[ZZ][ZZ]*b[ZZ][ZZ];
 }
 
-static gmx_inline void transpose(matrix src, matrix dest)
+static gmx_inline void transpose(gmx_cxx_const matrix src, matrix dest)
 {
     dest[XX][XX] = src[XX][XX];
     dest[YY][XX] = src[XX][YY];
@@ -658,7 +658,7 @@ static gmx_inline void transpose(matrix src, matrix dest)
     dest[ZZ][ZZ] = src[ZZ][ZZ];
 }
 
-static gmx_inline void tmmul(matrix a, matrix b, matrix dest)
+static gmx_inline void tmmul(gmx_cxx_const matrix a, gmx_cxx_const matrix b, matrix dest)
 {
     /* Computes dest=mmul(transpose(a),b,dest) - used in do_pr_pcoupl */
     dest[XX][XX] = a[XX][XX]*b[XX][XX]+a[YY][XX]*b[YY][XX]+a[ZZ][XX]*b[ZZ][XX];
@@ -672,7 +672,7 @@ static gmx_inline void tmmul(matrix a, matrix b, matrix dest)
     dest[ZZ][ZZ] = a[XX][ZZ]*b[XX][ZZ]+a[YY][ZZ]*b[YY][ZZ]+a[ZZ][ZZ]*b[ZZ][ZZ];
 }
 
-static gmx_inline void mtmul(matrix a, matrix b, matrix dest)
+static gmx_inline void mtmul(gmx_cxx_const matrix a, gmx_cxx_const matrix b, matrix dest)
 {
     /* Computes dest=mmul(a,transpose(b),dest) - used in do_pr_pcoupl */
     dest[XX][XX] = a[XX][XX]*b[XX][XX]+a[XX][YY]*b[XX][YY]+a[XX][ZZ]*b[XX][ZZ];
@@ -686,7 +686,7 @@ static gmx_inline void mtmul(matrix a, matrix b, matrix dest)
     dest[ZZ][ZZ] = a[ZZ][XX]*b[ZZ][XX]+a[ZZ][YY]*b[ZZ][YY]+a[ZZ][ZZ]*b[ZZ][ZZ];
 }
 
-static gmx_inline real det(matrix a)
+static gmx_inline real det(gmx_cxx_const matrix a)
 {
     return ( a[XX][XX]*(a[YY][YY]*a[ZZ][ZZ]-a[ZZ][YY]*a[YY][ZZ])
              -a[YY][XX]*(a[XX][YY]*a[ZZ][ZZ]-a[ZZ][YY]*a[XX][ZZ])
@@ -694,7 +694,7 @@ static gmx_inline real det(matrix a)
 }
 
 
-static gmx_inline void m_add(matrix a, matrix b, matrix dest)
+static gmx_inline void m_add(gmx_cxx_const matrix a, gmx_cxx_const matrix b, matrix dest)
 {
     dest[XX][XX] = a[XX][XX]+b[XX][XX];
     dest[XX][YY] = a[XX][YY]+b[XX][YY];
@@ -707,7 +707,7 @@ static gmx_inline void m_add(matrix a, matrix b, matrix dest)
     dest[ZZ][ZZ] = a[ZZ][ZZ]+b[ZZ][ZZ];
 }
 
-static gmx_inline void m_sub(matrix a, matrix b, matrix dest)
+static gmx_inline void m_sub(gmx_cxx_const matrix a, gmx_cxx_const matrix b, matrix dest)
 {
     dest[XX][XX] = a[XX][XX]-b[XX][XX];
     dest[XX][YY] = a[XX][YY]-b[XX][YY];
@@ -720,7 +720,7 @@ static gmx_inline void m_sub(matrix a, matrix b, matrix dest)
     dest[ZZ][ZZ] = a[ZZ][ZZ]-b[ZZ][ZZ];
 }
 
-static gmx_inline void msmul(matrix m1, real r1, matrix dest)
+static gmx_inline void msmul(gmx_cxx_const matrix m1, real r1, matrix dest)
 {
     dest[XX][XX] = r1*m1[XX][XX];
     dest[XX][YY] = r1*m1[XX][YY];
@@ -733,7 +733,7 @@ static gmx_inline void msmul(matrix m1, real r1, matrix dest)
     dest[ZZ][ZZ] = r1*m1[ZZ][ZZ];
 }
 
-static gmx_inline void m_inv_ur0(matrix src, matrix dest)
+static gmx_inline void m_inv_ur0(gmx_cxx_const matrix src, matrix dest)
 {
     double tmp = src[XX][XX]*src[YY][YY]*src[ZZ][ZZ];
     if (fabs(tmp) <= 100*GMX_REAL_MIN)
@@ -753,7 +753,7 @@ static gmx_inline void m_inv_ur0(matrix src, matrix dest)
     dest[YY][ZZ] = 0.0;
 }
 
-static gmx_inline void m_inv(matrix src, matrix dest)
+static gmx_inline void m_inv(gmx_cxx_const matrix src, matrix dest)
 {
     const real smallreal = (real)1.0e-24;
     const real largereal = (real)1.0e24;
@@ -779,7 +779,7 @@ static gmx_inline void m_inv(matrix src, matrix dest)
     dest[ZZ][ZZ] = c*(src[XX][XX]*src[YY][YY]-src[YY][XX]*src[XX][YY]);
 }
 
-static gmx_inline void mvmul(matrix a, const rvec src, rvec dest)
+static gmx_inline void mvmul(gmx_cxx_const matrix a, const rvec src, rvec dest)
 {
     dest[XX] = a[XX][XX]*src[XX]+a[XX][YY]*src[YY]+a[XX][ZZ]*src[ZZ];
     dest[YY] = a[YY][XX]*src[XX]+a[YY][YY]*src[YY]+a[YY][ZZ]*src[ZZ];
@@ -787,14 +787,14 @@ static gmx_inline void mvmul(matrix a, const rvec src, rvec dest)
 }
 
 
-static gmx_inline void mvmul_ur0(matrix a, const rvec src, rvec dest)
+static gmx_inline void mvmul_ur0(gmx_cxx_const matrix a, const rvec src, rvec dest)
 {
     dest[ZZ] = a[ZZ][XX]*src[XX]+a[ZZ][YY]*src[YY]+a[ZZ][ZZ]*src[ZZ];
     dest[YY] = a[YY][XX]*src[XX]+a[YY][YY]*src[YY];
     dest[XX] = a[XX][XX]*src[XX];
 }
 
-static gmx_inline void tmvmul_ur0(matrix a, const rvec src, rvec dest)
+static gmx_inline void tmvmul_ur0(gmx_cxx_const matrix a, const rvec src, rvec dest)
 {
     dest[XX] = a[XX][XX]*src[XX]+a[YY][XX]*src[YY]+a[ZZ][XX]*src[ZZ];
     dest[YY] =                   a[YY][YY]*src[YY]+a[ZZ][YY]*src[ZZ];
@@ -821,14 +821,14 @@ static gmx_inline void unitv_no_table(const rvec src, rvec dest)
     dest[ZZ] = linv*src[ZZ];
 }
 
-static void calc_lll(rvec box, rvec lll)
+static void calc_lll(const rvec box, rvec lll)
 {
     lll[XX] = 2.0*M_PI/box[XX];
     lll[YY] = 2.0*M_PI/box[YY];
     lll[ZZ] = 2.0*M_PI/box[ZZ];
 }
 
-static gmx_inline real trace(matrix m)
+static gmx_inline real trace(gmx_cxx_const matrix m)
 {
     return (m[XX][XX]+m[YY][YY]+m[ZZ][ZZ]);
 }
@@ -852,7 +852,7 @@ static gmx_inline int _mod(int a, int b, char *file, int line)
 }
 
 /* Operations on multidimensional rvecs, used e.g. in edsam.c */
-static gmx_inline void m_rveccopy(int dim, rvec *a, rvec *b)
+static gmx_inline void m_rveccopy(int dim, gmx_cxx_const rvec *a, rvec *b)
 {
     /* b = a */
     int i;
@@ -864,7 +864,7 @@ static gmx_inline void m_rveccopy(int dim, rvec *a, rvec *b)
 }
 
 /*computer matrix vectors from base vectors and angles */
-static gmx_inline void matrix_convert(matrix box, rvec vec, rvec angle)
+static gmx_inline void matrix_convert(matrix box, const rvec vec, rvec angle)
 {
     svmul(DEG2RAD, angle, angle);
     box[XX][XX] = vec[XX];
@@ -882,28 +882,6 @@ static gmx_inline void matrix_convert(matrix box, rvec vec, rvec angle)
 
 #ifdef __cplusplus
 }
-
-static gmx_inline real det(const matrix a)
-{
-    return ( a[XX][XX]*(a[YY][YY]*a[ZZ][ZZ]-a[ZZ][YY]*a[YY][ZZ])
-             -a[YY][XX]*(a[XX][YY]*a[ZZ][ZZ]-a[ZZ][YY]*a[XX][ZZ])
-             +a[ZZ][XX]*(a[XX][YY]*a[YY][ZZ]-a[YY][YY]*a[XX][ZZ]));
-}
-
-static gmx_inline void mvmul(const matrix a, const rvec src, rvec dest)
-{
-    dest[XX] = a[XX][XX]*src[XX]+a[XX][YY]*src[YY]+a[XX][ZZ]*src[ZZ];
-    dest[YY] = a[YY][XX]*src[XX]+a[YY][YY]*src[YY]+a[YY][ZZ]*src[ZZ];
-    dest[ZZ] = a[ZZ][XX]*src[XX]+a[ZZ][YY]*src[YY]+a[ZZ][ZZ]*src[ZZ];
-}
-
-static gmx_inline void tmvmul_ur0(const matrix a, const rvec src, rvec dest)
-{
-    dest[XX] = a[XX][XX]*src[XX]+a[YY][XX]*src[YY]+a[ZZ][XX]*src[ZZ];
-    dest[YY] =                   a[YY][YY]*src[YY]+a[ZZ][YY]*src[ZZ];
-    dest[ZZ] =                                     a[ZZ][ZZ]*src[ZZ];
-}
-
 #endif
 
 #endif
diff --git a/src/gromacs/utility/basedefinitions.h b/src/gromacs/utility/basedefinitions.h
index c8e65c2848..18a898cce5 100644
--- a/src/gromacs/utility/basedefinitions.h
+++ b/src/gromacs/utility/basedefinitions.h
@@ -159,9 +159,25 @@ typedef uint64_t gmx_uint64_t;
  */
 #define gmx_restrict __restrict
 
+/*! \def gmx_cxx_const
+ * \brief
+ * Keyword to work around C/C++ differences in possible const keyword usage.
+ *
+ * Some functions that do not modify their input parameters cannot declare
+ * those parameters as `const` and compile warning/error-free on both C and C++
+ * compilers because of differences in `const` semantics.  This macro can be
+ * used in cases where C++ allows `const`, but C does not like it, to make the
+ * same declaration work for both.
+ */
+#ifdef __cplusplus
+#define gmx_cxx_const const
+#else
+#define gmx_cxx_const
+#endif
+
 /*! \def gmx_unused
  * \brief
- * Attribute to suppres compiler warnings about unused function parameters.
+ * Attribute to suppress compiler warnings about unused function parameters.
  *
  * This attribute suppresses compiler warnings about unused function arguments
  * by marking them as possibly unused.  Some arguments are unused but