cpp conversion: fix One-Definition-Rule violations

Defining struct pj_opaque with different definitions is a violation
of the C++ One-Definition-Rule. When using link-time optimizations, this
could break badly.
The solution adopted here is to wrap those structures into a C++
anonymous namespace so they are considered different

82 files changed, 217 insertions, 11 deletions

diff --git a/src/PJ_aea.cpp b/src/PJ_aea.cpp
index e4d1dc4f..88929e3b 100644
--- a/src/PJ_aea.cpp
+++ b/src/PJ_aea.cpp
@@ -67,6 +67,7 @@ static double phi1_(double qs, double Te, double Tone_es) {
 }
 
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  ec;
     double  n;
@@ -80,6 +81,7 @@ struct pj_opaque {
     double  *en;
     int     ellips;
 };
+} // anonymous namespace
 
 
 static PJ *destructor (PJ *P, int errlev) {                        /* Destructor */
diff --git a/src/PJ_aeqd.cpp b/src/PJ_aeqd.cpp
index 72c7ae95..69bb76c3 100644
--- a/src/PJ_aeqd.cpp
+++ b/src/PJ_aeqd.cpp
@@ -32,13 +32,16 @@
 #include "projects.h"
 #include "proj_math.h"
 
+namespace { // anonymous namespace
 enum Mode {
     N_POLE = 0,
     S_POLE = 1,
     EQUIT  = 2,
     OBLIQ  = 3
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  sinph0;
     double  cosph0;
@@ -51,6 +54,7 @@ struct pj_opaque {
     enum Mode mode;
     struct geod_geodesic g;
 };
+} // anonymous namespace
 
 PROJ_HEAD(aeqd, "Azimuthal Equidistant") "\n\tAzi, Sph&Ell\n\tlat_0 guam";
 
diff --git a/src/PJ_affine.cpp b/src/PJ_affine.cpp
index b8fa4c68..c53d4e60 100644
--- a/src/PJ_affine.cpp
+++ b/src/PJ_affine.cpp
@@ -32,6 +32,7 @@
 PROJ_HEAD(affine, "Affine transformation");
 PROJ_HEAD(geogoffset, "Geographic Offset");
 
+namespace { // anonymous namespace
 struct pj_affine_coeffs {
     double s11;
     double s12;
@@ -44,7 +45,9 @@ struct pj_affine_coeffs {
     double s33;
     double tscale;
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque_affine {
     double xoff;
     double yoff;
@@ -53,6 +56,7 @@ struct pj_opaque_affine {
     struct pj_affine_coeffs forward;
     struct pj_affine_coeffs reverse;
 };
+} // anonymous namespace
 
 
 static PJ_COORD forward_4d(PJ_COORD obs, PJ *P) {
diff --git a/src/PJ_airy.cpp b/src/PJ_airy.cpp
index 037362b3..fa159bae 100644
--- a/src/PJ_airy.cpp
+++ b/src/PJ_airy.cpp
@@ -34,13 +34,16 @@
 PROJ_HEAD(airy, "Airy") "\n\tMisc Sph, no inv\n\tno_cut lat_b=";
 
 
+namespace { // anonymous namespace
 enum Mode {
     N_POLE = 0,
     S_POLE = 1,
     EQUIT  = 2,
     OBLIQ  = 3
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  p_halfpi;
     double  sinph0;
@@ -49,6 +52,7 @@ struct pj_opaque {
     enum Mode mode;
     int     no_cut; /* do not cut at hemisphere limit */
 };
+} // anonymous namespace
 
 
 # define EPS 1.e-10
diff --git a/src/PJ_aitoff.cpp b/src/PJ_aitoff.cpp
index 1af75469..ba1402a4 100644
--- a/src/PJ_aitoff.cpp
+++ b/src/PJ_aitoff.cpp
@@ -37,15 +37,19 @@
 #include "projects.h"
 
 
+namespace { // anonymous namespace
 enum Mode {
     AITOFF = 0,
     WINKEL_TRIPEL = 1
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  cosphi1;
     enum Mode mode;
 };
+} // anonymous namespace
 
 
 PROJ_HEAD(aitoff, "Aitoff") "\n\tMisc Sph";
diff --git a/src/PJ_axisswap.cpp b/src/PJ_axisswap.cpp
index d21eddb1..69edac8b 100644
--- a/src/PJ_axisswap.cpp
+++ b/src/PJ_axisswap.cpp
@@ -62,10 +62,12 @@ operation:
 
 PROJ_HEAD(axisswap, "Axis ordering");
 
+namespace { // anonymous namespace
 struct pj_opaque {
     unsigned int axis[4];
     int sign[4];
 };
+} // anonymous namespace
 
 static int sign(int x) {
     return (x > 0) - (x < 0);
diff --git a/src/PJ_bacon.cpp b/src/PJ_bacon.cpp
index f995e420..b00e1523 100644
--- a/src/PJ_bacon.cpp
+++ b/src/PJ_bacon.cpp
@@ -7,10 +7,12 @@
 #include "projects.h"
 
 
+namespace { // anonymous namespace
 struct pj_opaque {
 	int bacn;
 	int ortl;
 };
+} // anonymous namespace
 
 PROJ_HEAD(apian, "Apian Globular I") "\n\tMisc Sph, no inv";
 PROJ_HEAD(ortel, "Ortelius Oval") "\n\tMisc Sph, no inv";
diff --git a/src/PJ_bertin1953.cpp b/src/PJ_bertin1953.cpp
index 46420314..a551a6b2 100644
--- a/src/PJ_bertin1953.cpp
+++ b/src/PJ_bertin1953.cpp
@@ -21,9 +21,11 @@
 PROJ_HEAD(bertin1953, "Bertin 1953")
     "\n\tMisc Sph no inv.";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double cos_delta_phi, sin_delta_phi, cos_delta_gamma, sin_delta_gamma, deltaLambda;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {
diff --git a/src/PJ_bipc.cpp b/src/PJ_bipc.cpp
index 243ecccd..95cbcbb8 100644
--- a/src/PJ_bipc.cpp
+++ b/src/PJ_bipc.cpp
@@ -29,9 +29,11 @@ PROJ_HEAD(bipc, "Bipolar conic of western hemisphere") "\n\tConic Sph";
 # define R104   1.81514242207410275904
 
 
+namespace { // anonymous namespace
 struct pj_opaque {
     int noskew;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_bonne.cpp b/src/PJ_bonne.cpp
index 6c51af7c..0e979f64 100644
--- a/src/PJ_bonne.cpp
+++ b/src/PJ_bonne.cpp
@@ -9,6 +9,7 @@ PROJ_HEAD(bonne, "Bonne (Werner lat_1=90)")
     "\n\tConic Sph&Ell\n\tlat_1=";
 #define EPS10   1e-10
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double phi1;
     double cphi1;
@@ -16,6 +17,7 @@ struct pj_opaque {
     double m1;
     double *en;
 };
+} // anonymous namespace
 
 
 static XY e_forward (LP lp, PJ *P) {          /* Ellipsoidal, forward */
diff --git a/src/PJ_cass.cpp b/src/PJ_cass.cpp
index cc610940..2488f405 100644
--- a/src/PJ_cass.cpp
+++ b/src/PJ_cass.cpp
@@ -15,10 +15,12 @@ PROJ_HEAD(cass, "Cassini") "\n\tCyl, Sph&Ell";
 # define C5 .06666666666666666666
 
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double *en;
     double m0;
 };
+} // anonymous namespace
 
 
 
diff --git a/src/PJ_ccon.cpp b/src/PJ_ccon.cpp
index 6ff2d3b1..4ee53133 100644
--- a/src/PJ_ccon.cpp
+++ b/src/PJ_ccon.cpp
@@ -28,6 +28,7 @@
 
 #define EPS10   1e-10
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double phi1;
     double ctgphi1;
@@ -35,6 +36,7 @@ struct pj_opaque {
     double cosphi1;
     double *en;
 };
+} // anonymous namespace
 
 PROJ_HEAD(ccon, "Central Conic")
     "\n\tCentral Conic, Sph\n\tlat_1=";
diff --git a/src/PJ_cea.cpp b/src/PJ_cea.cpp
index ee7eebf5..3c9e128d 100644
--- a/src/PJ_cea.cpp
+++ b/src/PJ_cea.cpp
@@ -6,10 +6,12 @@
 #include "proj.h"
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double qp;
     double *apa;
 };
+} // anonymous namespace
 
 PROJ_HEAD(cea, "Equal Area Cylindrical") "\n\tCyl, Sph&Ell\n\tlat_ts=";
 # define EPS    1e-10
diff --git a/src/PJ_chamb.cpp b/src/PJ_chamb.cpp
index 8d8f05ee..0da3899b 100644
--- a/src/PJ_chamb.cpp
+++ b/src/PJ_chamb.cpp
@@ -7,6 +7,7 @@
 #include "projects.h"
 
 typedef struct { double r, Az; } VECT;
+namespace { // anonymous namespace
 struct pj_opaque {
     struct { /* control point data */
         double phi, lam;
@@ -18,6 +19,7 @@ struct pj_opaque {
     XY p;
     double beta_0, beta_1, beta_2;
 };
+} // anonymous namespace
 
 PROJ_HEAD(chamb, "Chamberlin Trimetric") "\n\tMisc Sph, no inv"
 "\n\tlat_1= lon_1= lat_2= lon_2= lat_3= lon_3=";
diff --git a/src/PJ_deformation.cpp b/src/PJ_deformation.cpp
index 1398f5fd..49f62c01 100644
--- a/src/PJ_deformation.cpp
+++ b/src/PJ_deformation.cpp
@@ -63,11 +63,13 @@ PROJ_HEAD(deformation, "Kinematic grid shift");
 #define TOL 1e-8
 #define MAX_ITERATIONS 10
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double t_obs;
     double t_epoch;
     PJ *cart;
 };
+} // anonymous namespace
 
 /********************************************************************************/
 static XYZ get_grid_shift(PJ* P, XYZ cartesian) {
diff --git a/src/PJ_eck3.cpp b/src/PJ_eck3.cpp
index 7993d781..beaf9357 100644
--- a/src/PJ_eck3.cpp
+++ b/src/PJ_eck3.cpp
@@ -10,9 +10,11 @@ PROJ_HEAD(putp1, "Putnins P1") "\n\tPCyl, Sph";
 PROJ_HEAD(wag6, "Wagner VI") "\n\tPCyl, Sph";
 PROJ_HEAD(kav7, "Kavraisky VII") "\n\tPCyl, Sph";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double C_x, C_y, A, B;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_eqc.cpp b/src/PJ_eqc.cpp
index b95471f7..f31da20a 100644
--- a/src/PJ_eqc.cpp
+++ b/src/PJ_eqc.cpp
@@ -6,9 +6,11 @@
 #include "proj.h"
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double rc;
 };
+} // anonymous namespace
 
 PROJ_HEAD(eqc, "Equidistant Cylindrical (Plate Carree)")
     "\n\tCyl, Sph\n\tlat_ts=[, lat_0=0]";
diff --git a/src/PJ_eqdc.cpp b/src/PJ_eqdc.cpp
index 468b16df..7e5cd0da 100644
--- a/src/PJ_eqdc.cpp
+++ b/src/PJ_eqdc.cpp
@@ -7,6 +7,7 @@
 #include "projects.h"
 #include "proj_math.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double phi1;
     double phi2;
@@ -17,6 +18,7 @@ struct pj_opaque {
     double *en;
     int     ellips;
 };
+} // anonymous namespace
 
 PROJ_HEAD(eqdc, "Equidistant Conic")
     "\n\tConic, Sph&Ell\n\tlat_1= lat_2=";
diff --git a/src/PJ_eqearth.cpp b/src/PJ_eqearth.cpp
index 34d85fa5..3547d683 100644
--- a/src/PJ_eqearth.cpp
+++ b/src/PJ_eqearth.cpp
@@ -31,11 +31,13 @@ PROJ_HEAD(eqearth, "Equal Earth") "\n\tPCyl, Sph&Ell";
 #define EPS 1e-11
 #define MAX_ITER 12
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  qp;
     double  rqda;
     double *apa;
 };
+} // anonymous namespace
 
 static XY e_forward (LP lp, PJ *P) {           /* Ellipsoidal/spheroidal, forward */
     XY xy = {0.0,0.0};
diff --git a/src/PJ_fouc_s.cpp b/src/PJ_fouc_s.cpp
index 8c223336..6f046b0a 100644
--- a/src/PJ_fouc_s.cpp
+++ b/src/PJ_fouc_s.cpp
@@ -11,9 +11,11 @@ PROJ_HEAD(fouc_s, "Foucaut Sinusoidal") "\n\tPCyl, Sph";
 #define MAX_ITER    10
 #define LOOP_TOL    1e-7
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double n, n1;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_geos.cpp b/src/PJ_geos.cpp
index ffe0771c..6bf7c3f3 100644
--- a/src/PJ_geos.cpp
+++ b/src/PJ_geos.cpp
@@ -36,6 +36,7 @@
 #include "projects.h"
 #include "proj_math.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double h;
     double radius_p;
@@ -46,6 +47,7 @@ struct pj_opaque {
     double C;
     int flip_axis;
 };
+} // anonymous namespace
 
 PROJ_HEAD(geos, "Geostationary Satellite View") "\n\tAzi, Sph&Ell\n\th=";
 
diff --git a/src/PJ_gn_sinu.cpp b/src/PJ_gn_sinu.cpp
index 2c7824ac..c9885012 100644
--- a/src/PJ_gn_sinu.cpp
+++ b/src/PJ_gn_sinu.cpp
@@ -15,10 +15,12 @@ PROJ_HEAD(mbtfps, "McBryde-Thomas Flat-Polar Sinusoidal") "\n\tPCyl, Sph";
 #define MAX_ITER 8
 #define LOOP_TOL 1e-7
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double *en;
     double m, n, C_x, C_y;
 };
+} // anonymous namespace
 
 
 static XY e_forward (LP lp, PJ *P) {          /* Ellipsoidal, forward */
diff --git a/src/PJ_gnom.cpp b/src/PJ_gnom.cpp
index 7313643f..27e5f925 100644
--- a/src/PJ_gnom.cpp
+++ b/src/PJ_gnom.cpp
@@ -11,18 +11,22 @@ PROJ_HEAD(gnom, "Gnomonic") "\n\tAzi, Sph";
 
 #define EPS10  1.e-10
 
+namespace { // anonymous namespace
 enum Mode {
     N_POLE = 0,
     S_POLE = 1,
     EQUIT  = 2,
     OBLIQ  = 3
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  sinph0;
     double  cosph0;
     enum Mode mode;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_goode.cpp b/src/PJ_goode.cpp
index 3f5a4f8c..14c78439 100644
--- a/src/PJ_goode.cpp
+++ b/src/PJ_goode.cpp
@@ -13,10 +13,12 @@ PROJ_HEAD(goode, "Goode Homolosine") "\n\tPCyl, Sph";
 
 C_NAMESPACE PJ *pj_sinu(PJ *), *pj_moll(PJ *);
 
+namespace { // anonymous namespace
 struct pj_opaque {
     PJ *sinu;
     PJ *moll;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_gstmerc.cpp b/src/PJ_gstmerc.cpp
index 6475f972..01ef796d 100644
--- a/src/PJ_gstmerc.cpp
+++ b/src/PJ_gstmerc.cpp
@@ -8,6 +8,7 @@
 PROJ_HEAD(gstmerc, "Gauss-Schreiber Transverse Mercator (aka Gauss-Laborde Reunion)")
     "\n\tCyl, Sph&Ell\n\tlat_0= lon_0= k_0=";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double lamc;
     double phic;
@@ -17,6 +18,7 @@ struct pj_opaque {
     double XS;
     double YS;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_hammer.cpp b/src/PJ_hammer.cpp
index 474d44ca..974bc813 100644
--- a/src/PJ_hammer.cpp
+++ b/src/PJ_hammer.cpp
@@ -11,10 +11,12 @@ PROJ_HEAD(hammer, "Hammer & Eckert-Greifendorff")
 
 #define EPS 1.0e-10
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double w;
     double m, rm;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_healpix.cpp b/src/PJ_healpix.cpp
index a7d42398..64b57a26 100644
--- a/src/PJ_healpix.cpp
+++ b/src/PJ_healpix.cpp
@@ -53,12 +53,14 @@ PROJ_HEAD(rhealpix, "rHEALPix") "\n\tSph&Ell\n\tnorth_square= south_square=";
 /* Fuzz to handle rounding errors: */
 # define EPS 1e-15
 
+namespace { // anonymous namespace
 struct pj_opaque {
     int north_square;
     int south_square;
     double qp;
     double *apa;
 };
+} // anonymous namespace
 
 typedef struct {
     int cn;         /* An integer 0--3 indicating the position of the polar cap. */
diff --git a/src/PJ_helmert.cpp b/src/PJ_helmert.cpp
index c19422cb..b2072a84 100644
--- a/src/PJ_helmert.cpp
+++ b/src/PJ_helmert.cpp
@@ -65,6 +65,7 @@ static LPZ helmert_reverse_3d (XYZ xyz, PJ *P);
 
 
 /***********************************************************************/
+namespace { // anonymous namespace
 struct pj_opaque_helmert {
 /************************************************************************
     Projection specific elements for the "helmert" PJ object
@@ -87,6 +88,7 @@ struct pj_opaque_helmert {
     int no_rotation, exact, fourparam;
     int is_position_vector; /* 1 = position_vector, 0 = coordinate_frame */
 };
+} // anonymous namespace
 
 
 /* Make the maths of the rotation operations somewhat more readable and textbook like */
diff --git a/src/PJ_hgridshift.cpp b/src/PJ_hgridshift.cpp
index 86c6cdee..9ed9ca02 100644
--- a/src/PJ_hgridshift.cpp
+++ b/src/PJ_hgridshift.cpp
@@ -10,10 +10,12 @@
 
 PROJ_HEAD(hgridshift, "Horizontal grid shift");
 
+namespace { // anonymous namespace
 struct pj_opaque_hgridshift {
     double t_final;
     double t_epoch;
 };
+} // anonymous namespace
 
 static XYZ forward_3d(LPZ lpz, PJ *P) {
     PJ_COORD point = {{0,0,0,0}};
diff --git a/src/PJ_horner.cpp b/src/PJ_horner.cpp
index 49e108c8..f2d8cb5a 100644
--- a/src/PJ_horner.cpp
+++ b/src/PJ_horner.cpp
@@ -92,13 +92,7 @@ PROJ_HEAD(horner, "Horner polynomial evaluation");
 #define horner_dealloc(x) pj_dealloc(x)
 #define horner_calloc(n,x) pj_calloc(n,x)
 
-
-struct horner;
-typedef struct horner HORNER;
-static UV      horner (const HORNER *transformation, PJ_DIRECTION direction, UV position);
-static HORNER *horner_alloc (size_t order, int complex_polynomia);
-static void    horner_free (HORNER *h);
-
+namespace { // anonymous namespace
 struct horner {
     int    uneg;     /* u axis negated? */
     int    vneg;     /* v axis negated? */
@@ -118,6 +112,12 @@ struct horner {
     UV *fwd_origin;  /* False longitude/latitude */
     UV *inv_origin;  /* False easting/northing   */
 };
+} // anonymous namespace
+
+typedef struct horner HORNER;
+static UV      horner_func (const HORNER *transformation, PJ_DIRECTION direction, UV position);
+static HORNER *horner_alloc (size_t order, int complex_polynomia);
+static void    horner_free (HORNER *h);
 
 /* e.g. degree = 2: a + bx + cy + dxx + eyy + fxy, i.e. 6 coefficients */
 #define horner_number_of_coefficients(order) \
@@ -181,7 +181,7 @@ static HORNER *horner_alloc (size_t order, int complex_polynomia) {
 
 
 /**********************************************************************/
-static UV horner (const HORNER *transformation, PJ_DIRECTION direction, UV position) {
+static UV horner_func (const HORNER *transformation, PJ_DIRECTION direction, UV position) {
 /***********************************************************************
 
 A reimplementation of the classic Engsager/Poder 2D Horner polynomial
@@ -297,12 +297,12 @@ summing the tiny high order elements first.
 
 
 static PJ_COORD horner_forward_4d (PJ_COORD point, PJ *P) {
-    point.uv = horner ((HORNER *) P->opaque, PJ_FWD, point.uv);
+    point.uv = horner_func ((HORNER *) P->opaque, PJ_FWD, point.uv);
     return point;
 }
 
 static PJ_COORD horner_reverse_4d (PJ_COORD point, PJ *P) {
-    point.uv = horner ((HORNER *) P->opaque, PJ_INV, point.uv);
+    point.uv = horner_func ((HORNER *) P->opaque, PJ_INV, point.uv);
     return point;
 }
 
diff --git a/src/PJ_igh.cpp b/src/PJ_igh.cpp
index 476d1c6b..60f5a4e8 100644
--- a/src/PJ_igh.cpp
+++ b/src/PJ_igh.cpp
@@ -32,10 +32,12 @@ static const double d180 = 180 * DEG_TO_RAD;
 
 static const double EPSLN = 1.e-10; /* allow a little 'slack' on zone edge positions */
 
+namespace { // anonymous namespace
 struct pj_opaque {
     struct PJconsts* pj[12]; \
     double dy0;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_imw_p.cpp b/src/PJ_imw_p.cpp
index 7bf9405a..a6e9d0bb 100644
--- a/src/PJ_imw_p.cpp
+++ b/src/PJ_imw_p.cpp
@@ -12,18 +12,22 @@ PROJ_HEAD(imw_p, "International Map of the World Polyconic")
 #define TOL 1e-10
 #define EPS 1e-10
 
+namespace { // anonymous namespace
 enum Mode {
     NONE_IS_ZERO  =  0, /* phi_1 and phi_2 != 0 */
     PHI_1_IS_ZERO =  1, /* phi_1 = 0 */
     PHI_2_IS_ZERO = -1  /* phi_2 = 0 */
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  P, Pp, Q, Qp, R_1, R_2, sphi_1, sphi_2, C2;
     double  phi_1, phi_2, lam_1;
     double  *en;
     enum Mode mode;
 };
+} // anonymous namespace
 
 
 static int phi12(PJ *P, double *del, double *sig) {
diff --git a/src/PJ_isea.cpp b/src/PJ_isea.cpp
index 6170b8a1..cc0ddf9e 100644
--- a/src/PJ_isea.cpp
+++ b/src/PJ_isea.cpp
@@ -46,10 +46,12 @@
 #define ISEA_STD_LAT 1.01722196792335072101
 #define ISEA_STD_LON .19634954084936207740
 
+namespace { // anonymous namespace
 struct hex {
         int iso;
         long x, y, z;
 };
+} // anonymous namespace
 
 /* y *must* be positive down as the xy /iso conversion assumes this */
 static void hex_xy(struct hex *h) {
@@ -124,12 +126,15 @@ static void hexbin2(double width, double x, double y, long *i, long *j) {
     *j = h.y;
 }
 
+namespace { // anonymous namespace
 enum isea_poly { ISEA_NONE, ISEA_ICOSAHEDRON = 20 };
 enum isea_topology { ISEA_HEXAGON=6, ISEA_TRIANGLE=3, ISEA_DIAMOND=4 };
 enum isea_address_form { ISEA_GEO, ISEA_Q2DI, ISEA_SEQNUM, ISEA_INTERLEAVE,
     ISEA_PLANE, ISEA_Q2DD, ISEA_PROJTRI, ISEA_VERTEX2DD, ISEA_HEX
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct isea_dgg {
     int polyhedron; /* ignored, icosahedron */
     double  o_lat, o_lon, o_az; /* orientation, radians */
@@ -143,29 +148,38 @@ struct isea_dgg {
     int quad; /* quad of last transformed point */
     unsigned long serial;
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct isea_pt {
     double x, y;
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct isea_geo {
     double lon, lat;
 };
+} // anonymous namespace
 
 /* ENDINC */
 
+namespace { // anonymous namespace
 enum snyder_polyhedron {
     SNYDER_POLY_HEXAGON, SNYDER_POLY_PENTAGON,
     SNYDER_POLY_TETRAHEDRON, SNYDER_POLY_CUBE,
     SNYDER_POLY_OCTAHEDRON, SNYDER_POLY_DODECAHEDRON,
     SNYDER_POLY_ICOSAHEDRON
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct snyder_constants {
     double          g, G, theta;
     /* cppcheck-suppress unusedStructMember */
     double ea_w, ea_a, ea_b, g_w, g_a, g_b;
 };
+} // anonymous namespace
 
 /* TODO put these in radians to avoid a later conversion */
 static const struct snyder_constants constants[] = {
@@ -974,9 +988,11 @@ static struct isea_pt isea_forward(struct isea_dgg *g, struct isea_geo *in)
 
 PROJ_HEAD(isea, "Icosahedral Snyder Equal Area") "\n\tSph";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     struct isea_dgg dgg;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_krovak.cpp b/src/PJ_krovak.cpp
index 7e0488f0..7728002a 100644
--- a/src/PJ_krovak.cpp
+++ b/src/PJ_krovak.cpp
@@ -90,6 +90,7 @@ PROJ_HEAD(krovak, "Krovak") "\n\tPCyl, Ell";
 /* Not sure at all of the appropriate number for MAX_ITER... */
 #define MAX_ITER 100
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double alpha;
     double k;
@@ -98,6 +99,7 @@ struct pj_opaque {
     double ad;
     int czech;
 };
+} // anonymous namespace
 
 
 static XY e_forward (LP lp, PJ *P) {                /* Ellipsoidal, forward */
diff --git a/src/PJ_labrd.cpp b/src/PJ_labrd.cpp
index e40bbcbd..c72aeb93 100644
--- a/src/PJ_labrd.cpp
+++ b/src/PJ_labrd.cpp
@@ -8,9 +8,11 @@
 PROJ_HEAD(labrd, "Laborde") "\n\tCyl, Sph\n\tSpecial for Madagascar";
 #define EPS 1.e-10
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  kRg, p0s, A, C, Ca, Cb, Cc, Cd;
 };
+} // anonymous namespace
 
 
 static XY e_forward (LP lp, PJ *P) {          /* Ellipsoidal, forward */
diff --git a/src/PJ_laea.cpp b/src/PJ_laea.cpp
index 02b34858..f1626a55 100644
--- a/src/PJ_laea.cpp
+++ b/src/PJ_laea.cpp
@@ -6,13 +6,16 @@
 
 PROJ_HEAD(laea, "Lambert Azimuthal Equal Area") "\n\tAzi, Sph&Ell";
 
+namespace { // anonymous namespace
 enum Mode {
     N_POLE = 0,
     S_POLE = 1,
     EQUIT  = 2,
     OBLIQ  = 3
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double sinb1;
     double cosb1;
@@ -25,6 +28,7 @@ struct pj_opaque {
     double *apa;
     enum Mode mode;
 };
+} // anonymous namespace
 
 #define EPS10   1.e-10
 
diff --git a/src/PJ_lagrng.cpp b/src/PJ_lagrng.cpp
index f5363287..30306db4 100644
--- a/src/PJ_lagrng.cpp
+++ b/src/PJ_lagrng.cpp
@@ -9,6 +9,7 @@ PROJ_HEAD(lagrng, "Lagrange") "\n\tMisc Sph\n\tW=";
 
 #define TOL 1e-10
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  a1;
     double  a2;
@@ -17,6 +18,7 @@ struct pj_opaque {
     double  rw;
     double  w;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_lcc.cpp b/src/PJ_lcc.cpp
index 5c430ea0..9483c085 100644
--- a/src/PJ_lcc.cpp
+++ b/src/PJ_lcc.cpp
@@ -9,6 +9,7 @@ PROJ_HEAD(lcc, "Lambert Conformal Conic")
 
 #define EPS10 1.e-10
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double phi1;
     double phi2;
@@ -16,6 +17,7 @@ struct pj_opaque {
     double rho0;
     double c;
 };
+} // anonymous namespace
 
 
 static XY e_forward (LP lp, PJ *P) {          /* Ellipsoidal, forward */
diff --git a/src/PJ_lcca.cpp b/src/PJ_lcca.cpp
index cbb18709..add6dcc7 100644
--- a/src/PJ_lcca.cpp
+++ b/src/PJ_lcca.cpp
@@ -59,11 +59,13 @@ PROJ_HEAD(lcca, "Lambert Conformal Conic Alternative")
 #define MAX_ITER 10
 #define DEL_TOL 1e-12
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double *en;
     double r0, l, M0;
     double C;
 };
+} // anonymous namespace
 
 
 static double fS(double S, double C) {        /* func to compute dr */
diff --git a/src/PJ_loxim.cpp b/src/PJ_loxim.cpp
index 28e955d9..fc412997 100644
--- a/src/PJ_loxim.cpp
+++ b/src/PJ_loxim.cpp
@@ -10,11 +10,13 @@ PROJ_HEAD(loxim, "Loximuthal") "\n\tPCyl Sph";
 
 #define EPS 1e-8
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double phi1;
     double cosphi1;
     double tanphi1;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_lsat.cpp b/src/PJ_lsat.cpp
index e3e7e026..ba829d42 100644
--- a/src/PJ_lsat.cpp
+++ b/src/PJ_lsat.cpp
@@ -12,10 +12,12 @@ PROJ_HEAD(lsat, "Space oblique for LANDSAT")
 
 #define TOL 1e-7
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double a2, a4, b, c1, c3;
     double q, t, u, w, p22, sa, ca, xj, rlm, rlm2;
 };
+} // anonymous namespace
 
 static void seraz0(double lam, double mult, PJ *P) {
     struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
diff --git a/src/PJ_misrsom.cpp b/src/PJ_misrsom.cpp
index 537172c1..3d8adbe9 100644
--- a/src/PJ_misrsom.cpp
+++ b/src/PJ_misrsom.cpp
@@ -33,10 +33,12 @@ PROJ_HEAD(misrsom, "Space oblique for MISR")
 
 #define TOL 1e-7
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double a2, a4, b, c1, c3;
     double q, t, u, w, p22, sa, ca, xj, rlm, rlm2;
 };
+} // anonymous namespace
 
 static void seraz0(double lam, double mult, PJ *P) {
     struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
diff --git a/src/PJ_mod_ster.cpp b/src/PJ_mod_ster.cpp
index ad5c9cdb..7ef34f0a 100644
--- a/src/PJ_mod_ster.cpp
+++ b/src/PJ_mod_ster.cpp
@@ -12,11 +12,13 @@ PROJ_HEAD(gs50, "Mod. Stereographic of 50 U.S.") "\n\tAzi(mod)";
 
 #define EPSLN 1e-12
 
+namespace { // anonymous namespace
 struct pj_opaque {
     const COMPLEX *zcoeff; \
     double  cchio, schio; \
     int     n;
 };
+} // anonymous namespace
 
 
 static XY e_forward (LP lp, PJ *P) {          /* Ellipsoidal, forward */
diff --git a/src/PJ_moll.cpp b/src/PJ_moll.cpp
index ed7e946d..aed16132 100644
--- a/src/PJ_moll.cpp
+++ b/src/PJ_moll.cpp
@@ -12,9 +12,11 @@ PROJ_HEAD(wag5, "Wagner V") "\n\tPCyl, Sph";
 #define MAX_ITER    10
 #define LOOP_TOL    1e-7
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  C_x, C_y, C_p;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_molodensky.cpp b/src/PJ_molodensky.cpp
index 6b231081..6ed8dd33 100644
--- a/src/PJ_molodensky.cpp
+++ b/src/PJ_molodensky.cpp
@@ -56,6 +56,7 @@ PROJ_HEAD(molodensky, "Molodensky transform");
 static XYZ forward_3d(LPZ lpz, PJ *P);
 static LPZ reverse_3d(XYZ xyz, PJ *P);
 
+namespace { // anonymous namespace
 struct pj_opaque_molodensky {
     double dx;
     double dy;
@@ -64,6 +65,7 @@ struct pj_opaque_molodensky {
     double df;
     int    abridged;
 };
+} // anonymous namespace
 
 
 static double RN (double a, double es, double phi) {
diff --git a/src/PJ_nsper.cpp b/src/PJ_nsper.cpp
index e6ecb852..beace3d9 100644
--- a/src/PJ_nsper.cpp
+++ b/src/PJ_nsper.cpp
@@ -4,13 +4,16 @@
 #include "projects.h"
 #include "proj_math.h"
 
+namespace { // anonymous namespace
 enum Mode {
     N_POLE = 0,
     S_POLE = 1,
     EQUIT  = 2,
     OBLIQ  = 3
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  height;
     double  sinph0;
@@ -27,6 +30,7 @@ struct pj_opaque {
     enum Mode mode;
     int     tilt;
 };
+} // anonymous namespace
 
 PROJ_HEAD(nsper, "Near-sided perspective") "\n\tAzi, Sph\n\th=";
 PROJ_HEAD(tpers, "Tilted perspective") "\n\tAzi, Sph\n\ttilt= azi= h=";
diff --git a/src/PJ_ob_tran.cpp b/src/PJ_ob_tran.cpp
index 1a9417b8..ee1dc465 100644
--- a/src/PJ_ob_tran.cpp
+++ b/src/PJ_ob_tran.cpp
@@ -7,11 +7,13 @@
 #include "proj.h"
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     struct PJconsts *link;
     double  lamp;
     double  cphip, sphip;
 };
+} // anonymous namespace
 
 PROJ_HEAD(ob_tran, "General Oblique Transformation") "\n\tMisc Sph"
 "\n\to_proj= plus parameters for projection"
diff --git a/src/PJ_ocea.cpp b/src/PJ_ocea.cpp
index 81c506fe..414c296f 100644
--- a/src/PJ_ocea.cpp
+++ b/src/PJ_ocea.cpp
@@ -8,6 +8,7 @@
 PROJ_HEAD(ocea, "Oblique Cylindrical Equal Area") "\n\tCyl, Sph"
     "lonc= alpha= or\n\tlat_1= lat_2= lon_1= lon_2=";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  rok;
     double  rtk;
@@ -16,6 +17,7 @@ struct pj_opaque {
     double  singam;
     double  cosgam;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_oea.cpp b/src/PJ_oea.cpp
index b39e8d5a..0b558f83 100644
--- a/src/PJ_oea.cpp
+++ b/src/PJ_oea.cpp
@@ -6,12 +6,14 @@
 
 PROJ_HEAD(oea, "Oblated Equal Area") "\n\tMisc Sph\n\tn= m= theta=";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  theta;
     double  m, n;
     double  two_r_m, two_r_n, rm, rn, hm, hn;
     double  cp0, sp0;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_omerc.cpp b/src/PJ_omerc.cpp
index 27b65cc7..dbf90230 100644
--- a/src/PJ_omerc.cpp
+++ b/src/PJ_omerc.cpp
@@ -33,11 +33,13 @@ PROJ_HEAD(omerc, "Oblique Mercator")
     "\n\tCyl, Sph&Ell no_rot\n\t"
     "alpha= [gamma=] [no_off] lonc= or\n\t lon_1= lat_1= lon_2= lat_2=";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  A, B, E, AB, ArB, BrA, rB, singam, cosgam, sinrot, cosrot;
     double  v_pole_n, v_pole_s, u_0;
     int no_rot;
 };
+} // anonymous namespace
 
 #define TOL 1.e-7
 #define EPS 1.e-10
diff --git a/src/PJ_ortho.cpp b/src/PJ_ortho.cpp
index 0e3641c0..4f5cf99a 100644
--- a/src/PJ_ortho.cpp
+++ b/src/PJ_ortho.cpp
@@ -7,18 +7,22 @@
 
 PROJ_HEAD(ortho, "Orthographic") "\n\tAzi, Sph";
 
+namespace { // anonymous namespace
 enum Mode {
     N_POLE = 0,
     S_POLE = 1,
     EQUIT  = 2,
     OBLIQ  = 3
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  sinph0;
     double  cosph0;
     enum Mode mode;
 };
+} // anonymous namespace
 
 #define EPS10 1.e-10
 
diff --git a/src/PJ_pipeline.cpp b/src/PJ_pipeline.cpp
index c20454df..bf28e93e 100644
--- a/src/PJ_pipeline.cpp
+++ b/src/PJ_pipeline.cpp
@@ -109,12 +109,14 @@ Thomas Knudsen, thokn@sdfe.dk, 2016-05-20
 PROJ_HEAD(pipeline,         "Transformation pipeline manager");
 
 /* Projection specific elements for the PJ object */
+namespace { // anonymous namespace
 struct pj_opaque {
     int steps;
     char **argv;
     char **current_argv;
     PJ **pipeline;
 };
+} // anonymous namespace
 
 
 
diff --git a/src/PJ_poly.cpp b/src/PJ_poly.cpp
index 3bf7a8dd..9eb97467 100644
--- a/src/PJ_poly.cpp
+++ b/src/PJ_poly.cpp
@@ -9,10 +9,12 @@
 PROJ_HEAD(poly, "Polyconic (American)")
     "\n\tConic, Sph&Ell";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double ml0; \
     double *en;
 };
+} // anonymous namespace
 
 #define TOL 1e-10
 #define CONV    1e-10
diff --git a/src/PJ_putp3.cpp b/src/PJ_putp3.cpp
index 6e85d35f..c55a1732 100644
--- a/src/PJ_putp3.cpp
+++ b/src/PJ_putp3.cpp
@@ -2,9 +2,11 @@
 #include <errno.h>
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  A;
 };
+} // anonymous namespace
 
 PROJ_HEAD(putp3, "Putnins P3") "\n\tPCyl, Sph";
 PROJ_HEAD(putp3p, "Putnins P3'") "\n\tPCyl, Sph";
diff --git a/src/PJ_putp4p.cpp b/src/PJ_putp4p.cpp
index 77a18651..2ad20d1b 100644
--- a/src/PJ_putp4p.cpp
+++ b/src/PJ_putp4p.cpp
@@ -5,9 +5,11 @@
 
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double C_x, C_y;
 };
+} // anonymous namespace
 
 PROJ_HEAD(putp4p, "Putnins P4'") "\n\tPCyl, Sph";
 PROJ_HEAD(weren, "Werenskiold I") "\n\tPCyl, Sph";
diff --git a/src/PJ_putp5.cpp b/src/PJ_putp5.cpp
index d73e9368..41849f33 100644
--- a/src/PJ_putp5.cpp
+++ b/src/PJ_putp5.cpp
@@ -5,9 +5,11 @@
 
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  A, B;
 };
+} // anonymous namespace
 
 PROJ_HEAD(putp5, "Putnins P5") "\n\tPCyl, Sph";
 PROJ_HEAD(putp5p, "Putnins P5'") "\n\tPCyl, Sph";
diff --git a/src/PJ_putp6.cpp b/src/PJ_putp6.cpp
index fcd8146f..bfa7d908 100644
--- a/src/PJ_putp6.cpp
+++ b/src/PJ_putp6.cpp
@@ -5,9 +5,11 @@
 
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double C_x, C_y, A, B, D;
 };
+} // anonymous namespace
 
 PROJ_HEAD(putp6, "Putnins P6") "\n\tPCyl, Sph";
 PROJ_HEAD(putp6p, "Putnins P6'") "\n\tPCyl, Sph";
diff --git a/src/PJ_qsc.cpp b/src/PJ_qsc.cpp
index 767ed4a8..bca7c4fb 100644
--- a/src/PJ_qsc.cpp
+++ b/src/PJ_qsc.cpp
@@ -46,6 +46,7 @@
 #include "projects.h"
 
 /* The six cube faces. */
+namespace { // anonymous namespace
 enum Face {
     FACE_FRONT  = 0,
     FACE_RIGHT  = 1,
@@ -54,7 +55,9 @@ enum Face {
     FACE_TOP    = 4,
     FACE_BOTTOM = 5
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
         enum Face face;
         double a_squared;
@@ -62,18 +65,21 @@ struct pj_opaque {
         double one_minus_f;
         double one_minus_f_squared;
 };
+} // anonymous namespace
 PROJ_HEAD(qsc, "Quadrilateralized Spherical Cube") "\n\tAzi, Sph";
 
 #define EPS10 1.e-10
 
 /* The four areas on a cube face. AREA_0 is the area of definition,
  * the other three areas are counted counterclockwise. */
+namespace { // anonymous namespace
 enum Area {
     AREA_0 = 0,
     AREA_1 = 1,
     AREA_2 = 2,
     AREA_3 = 3
 };
+} // anonymous namespace
 
 /* Helper function for forward projection: compute the theta angle
  * and determine the area number. */
diff --git a/src/PJ_robin.cpp b/src/PJ_robin.cpp
index 19bdc2dc..987977ae 100644
--- a/src/PJ_robin.cpp
+++ b/src/PJ_robin.cpp
@@ -18,9 +18,11 @@ http://article.gmane.org/gmane.comp.gis.proj-4.devel/6039
 http://trac.osgeo.org/proj/ticket/113
 */
 
+namespace { // anonymous namespace
 struct COEFS {
     float c0, c1, c2, c3;
 };
+} // anonymous namespace
 
 static const struct COEFS X[] = {
     {1.0f, 2.2199e-17f, -7.15515e-05f, 3.1103e-06f},
diff --git a/src/PJ_rpoly.cpp b/src/PJ_rpoly.cpp
index 24360965..a3b07c45 100644
--- a/src/PJ_rpoly.cpp
+++ b/src/PJ_rpoly.cpp
@@ -5,12 +5,14 @@
 
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  phi1;
     double  fxa;
     double  fxb;
     int     mode;
 };
+} // anonymous namespace
 
 PROJ_HEAD(rpoly, "Rectangular Polyconic")
     "\n\tConic, Sph, no inv\n\tlat_ts=";
diff --git a/src/PJ_sch.cpp b/src/PJ_sch.cpp
index 4a0b1fb8..23b6c4c2 100644
--- a/src/PJ_sch.cpp
+++ b/src/PJ_sch.cpp
@@ -39,6 +39,7 @@
 #include "projects.h"
 #include "geocent.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double plat; /*Peg Latitude */
     double plon; /*Peg Longitude*/
@@ -50,6 +51,7 @@ struct pj_opaque {
     GeocentricInfo sph;
     GeocentricInfo elp_0;
 };
+} // anonymous namespace
 
 PROJ_HEAD(sch, "Spherical Cross-track Height") "\n\tMisc\n\tplat_0= plon_0= phdg_0= [h_0=]";
 
diff --git a/src/PJ_sconics.cpp b/src/PJ_sconics.cpp
index 4efec86f..788bdb02 100644
--- a/src/PJ_sconics.cpp
+++ b/src/PJ_sconics.cpp
@@ -5,6 +5,7 @@
 #include "proj_math.h"
 
 
+namespace { // anonymous namespace
 enum Type {
     EULER  = 0,
     MURD1  = 1,
@@ -14,7 +15,9 @@ enum Type {
     TISSOT = 5,
     VITK1  = 6
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  n;
     double  rho_c;
@@ -23,6 +26,7 @@ struct pj_opaque {
     double  c1, c2;
     enum Type type;
 };
+} // anonymous namespace
 
 
 #define EPS10   1.e-10
diff --git a/src/PJ_somerc.cpp b/src/PJ_somerc.cpp
index 6a98f76f..b82f1a58 100644
--- a/src/PJ_somerc.cpp
+++ b/src/PJ_somerc.cpp
@@ -8,9 +8,11 @@
 
 PROJ_HEAD(somerc, "Swiss. Obl. Mercator") "\n\tCyl, Ell\n\tFor CH1903";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double K, c, hlf_e, kR, cosp0, sinp0;
 };
+} // anonymous namespace
 
 #define EPS 1.e-10
 #define NITER 6
diff --git a/src/PJ_stere.cpp b/src/PJ_stere.cpp
index 94e7f91d..58d5858d 100644
--- a/src/PJ_stere.cpp
+++ b/src/PJ_stere.cpp
@@ -8,13 +8,16 @@ PROJ_HEAD(stere, "Stereographic") "\n\tAzi, Sph&Ell\n\tlat_ts=";
 PROJ_HEAD(ups, "Universal Polar Stereographic") "\n\tAzi, Sph&Ell\n\tsouth";
 
 
+namespace { // anonymous namespace
 enum Mode {
     S_POLE = 0,
     N_POLE = 1,
     OBLIQ  = 2,
     EQUIT  = 3
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double phits;
     double sinX1;
@@ -22,6 +25,7 @@ struct pj_opaque {
     double akm1;
     enum Mode mode;
 };
+} // anonymous namespace
 
 #define sinph0  static_cast<struct pj_opaque*>(P->opaque)->sinX1
 #define cosph0  static_cast<struct pj_opaque*>(P->opaque)->cosX1
diff --git a/src/PJ_sterea.cpp b/src/PJ_sterea.cpp
index 4c2fe2a3..05a6e5e3 100644
--- a/src/PJ_sterea.cpp
+++ b/src/PJ_sterea.cpp
@@ -29,12 +29,14 @@
 #include "proj_math.h"
 
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double phic0;
     double cosc0, sinc0;
     double R2;
     void *en;
 };
+} // anonymous namespace
 
 
 PROJ_HEAD(sterea, "Oblique Stereographic Alternative") "\n\tAzimuthal, Sph&Ell";
diff --git a/src/PJ_sts.cpp b/src/PJ_sts.cpp
index 4aece68e..bc56ed81 100644
--- a/src/PJ_sts.cpp
+++ b/src/PJ_sts.cpp
@@ -11,10 +11,12 @@ PROJ_HEAD(fouc,    "Foucaut")             "\n\tPCyl, Sph";
 PROJ_HEAD(mbt_s,   "McBryde-Thomas Flat-Polar Sine (No. 1)") "\n\tPCyl, Sph";
 
 
+namespace { // anonymous namespace
 struct pj_opaque {
 	double C_x, C_y, C_p;
 	int tan_mode;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_tmerc.cpp b/src/PJ_tmerc.cpp
index 55f878c9..ac6319ff 100644
--- a/src/PJ_tmerc.cpp
+++ b/src/PJ_tmerc.cpp
@@ -9,11 +9,13 @@
 PROJ_HEAD(tmerc, "Transverse Mercator") "\n\tCyl, Sph&Ell";
 
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  esp;
     double  ml0;
     double  *en;
 };
+} // anonymous namespace
 
 #define EPS10   1.e-10
 #define FC1 1.
diff --git a/src/PJ_tpeqd.cpp b/src/PJ_tpeqd.cpp
index 5691cd7b..a1c049aa 100644
--- a/src/PJ_tpeqd.cpp
+++ b/src/PJ_tpeqd.cpp
@@ -8,10 +8,12 @@
 PROJ_HEAD(tpeqd, "Two Point Equidistant")
     "\n\tMisc Sph\n\tlat_1= lon_1= lat_2= lon_2=";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double cp1, sp1, cp2, sp2, ccs, cs, sc, r2z0, z02, dlam2;
     double hz0, thz0, rhshz0, ca, sa, lp, lamc;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_unitconvert.cpp b/src/PJ_unitconvert.cpp
index 7476620e..09eb3ae8 100644
--- a/src/PJ_unitconvert.cpp
+++ b/src/PJ_unitconvert.cpp
@@ -78,19 +78,23 @@ PROJ_HEAD(unitconvert, "Unit conversion");
 
 typedef double (*tconvert)(double);
 
+namespace { // anonymous namespace
 struct TIME_UNITS {
     char        *id;        /* units keyword */
     tconvert     t_in;      /* unit -> mod. julian date function pointer */
     tconvert     t_out;     /* mod. julian date > unit function pointer */
     char        *name;      /* comments */
 };
+} // anonymous namespace
 
+namespace { // anonymous namespace
 struct pj_opaque_unitconvert {
     int     t_in_id;        /* time unit id for the time input unit   */
     int     t_out_id;       /* time unit id for the time output unit  */
     double  xy_factor;      /* unit conversion factor for horizontal components */
     double  z_factor;       /* unit conversion factor for vertical components */
 };
+} // anonymous namespace
 
 
 /***********************************************************************/
diff --git a/src/PJ_urm5.cpp b/src/PJ_urm5.cpp
index 6a208647..f16d1534 100644
--- a/src/PJ_urm5.cpp
+++ b/src/PJ_urm5.cpp
@@ -8,9 +8,11 @@
 
 PROJ_HEAD(urm5, "Urmaev V") "\n\tPCyl, Sph, no inv\n\tn= q= alpha=";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double m, rmn, q3, n;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_urmfps.cpp b/src/PJ_urmfps.cpp
index 1d147b9c..848ba4f9 100644
--- a/src/PJ_urmfps.cpp
+++ b/src/PJ_urmfps.cpp
@@ -9,9 +9,11 @@
 PROJ_HEAD(urmfps, "Urmaev Flat-Polar Sinusoidal") "\n\tPCyl, Sph\n\tn=";
 PROJ_HEAD(wag1, "Wagner I (Kavraisky VI)") "\n\tPCyl, Sph";
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double  n, C_y;
 };
+} // anonymous namespace
 
 #define C_x 0.8773826753
 #define Cy 1.139753528477
diff --git a/src/PJ_vandg2.cpp b/src/PJ_vandg2.cpp
index 588366cf..f414f1ef 100644
--- a/src/PJ_vandg2.cpp
+++ b/src/PJ_vandg2.cpp
@@ -5,9 +5,11 @@
 
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     int vdg3;
 };
+} // anonymous namespace
 
 PROJ_HEAD(vandg2, "van der Grinten II") "\n\tMisc Sph, no inv";
 PROJ_HEAD(vandg3, "van der Grinten III") "\n\tMisc Sph, no inv";
diff --git a/src/PJ_vgridshift.cpp b/src/PJ_vgridshift.cpp
index 8aad3777..bf1300c7 100644
--- a/src/PJ_vgridshift.cpp
+++ b/src/PJ_vgridshift.cpp
@@ -10,11 +10,13 @@
 
 PROJ_HEAD(vgridshift, "Vertical grid shift");
 
+namespace { // anonymous namespace
 struct pj_opaque_vgridshift {
     double t_final;
     double t_epoch;
     double forward_multiplier;
 };
+} // anonymous namespace
 
 static XYZ forward_3d(LPZ lpz, PJ *P) {
     struct pj_opaque_vgridshift *Q = (struct pj_opaque_vgridshift *) P->opaque;
diff --git a/src/PJ_wag3.cpp b/src/PJ_wag3.cpp
index 0eeb73df..f0443688 100644
--- a/src/PJ_wag3.cpp
+++ b/src/PJ_wag3.cpp
@@ -9,9 +9,11 @@ PROJ_HEAD(wag3, "Wagner III") "\n\tPCyl, Sph\n\tlat_ts=";
 
 #define TWOTHIRD 0.6666666666666666666667
 
+namespace { // anonymous namespace
 struct pj_opaque {
 	double	C_x;
 };
+} // anonymous namespace
 
 
 static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
diff --git a/src/PJ_wink1.cpp b/src/PJ_wink1.cpp
index 6640f995..e466988f 100644
--- a/src/PJ_wink1.cpp
+++ b/src/PJ_wink1.cpp
@@ -7,9 +7,11 @@
 
 PROJ_HEAD(wink1, "Winkel I") "\n\tPCyl, Sph\n\tlat_ts=";
 
+namespace { // anonymous namespace
 struct pj_opaque {
 	double	cosphi1;
 };
+} // anonymous namespace
 
 
 
diff --git a/src/PJ_wink2.cpp b/src/PJ_wink2.cpp
index 9da65eaa..3935372a 100644
--- a/src/PJ_wink2.cpp
+++ b/src/PJ_wink2.cpp
@@ -7,7 +7,11 @@
 
 PROJ_HEAD(wink2, "Winkel II") "\n\tPCyl, Sph, no inv\n\tlat_1=";
 
-struct pj_opaque { double	cosphi1; };
+namespace { // anonymous namespace
+struct pj_opaque {
+    double	cosphi1;
+};
+} // anonymous namespace
 
 #define MAX_ITER    10
 #define LOOP_TOL    1e-7
diff --git a/src/gie.cpp b/src/gie.cpp
index 74d78db5..77c21083 100644
--- a/src/gie.cpp
+++ b/src/gie.cpp
@@ -1020,6 +1020,7 @@ static int dispatch (const char *cmnd, const char *args) {
 
 
 
+namespace { // anonymous namespace
 struct errno_vs_err_const {const char *the_err_const; int the_errno;};
 static const struct errno_vs_err_const lookup[] = {
     {"pjd_err_no_args"                  ,  -1},
@@ -1084,6 +1085,7 @@ static const struct errno_vs_err_const lookup[] = {
     {"pjd_err_unknown"                  ,  9999},
     {"pjd_err_enomem"                   ,  ENOMEM},
 };
+} // anonymous namespace
 
 static const struct errno_vs_err_const unknown = {"PJD_ERR_UNKNOWN", 9999};
 
diff --git a/src/pj_gauss.cpp b/src/pj_gauss.cpp
index 4520bb39..45b93f59 100644
--- a/src/pj_gauss.cpp
+++ b/src/pj_gauss.cpp
@@ -32,12 +32,14 @@
 
 #define MAX_ITER 20
 
+namespace { // anonymous namespace
 struct GAUSS {
     double C;
     double K;
     double e;
     double ratexp;
 };
+} // anonymous namespace
 #define DEL_TOL 1e-14
 
 static double srat(double esinp, double ratexp) {
diff --git a/src/proj_etmerc.cpp b/src/proj_etmerc.cpp
index 0ba710d7..b521c329 100644
--- a/src/proj_etmerc.cpp
+++ b/src/proj_etmerc.cpp
@@ -47,6 +47,7 @@
 #include "proj_math.h"
 
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double    Qn;    /* Merid. quad., scaled to the projection */ \
     double    Zb;    /* Radius vector in polar coord. systems  */ \
@@ -55,6 +56,7 @@ struct pj_opaque {
     double    utg[6]; /* Constants for transv. merc. -> geo */ \
     double    gtu[6]; /* Constants for geo -> transv. merc. */
 };
+} // anonymous namespace
 
 PROJ_HEAD(etmerc, "Extended Transverse Mercator")
     "\n\tCyl, Sph\n\tlat_ts=(0)\nlat_0=(0)";
diff --git a/src/proj_mdist.cpp b/src/proj_mdist.cpp
index 777f704d..c645d117 100644
--- a/src/proj_mdist.cpp
+++ b/src/proj_mdist.cpp
@@ -37,12 +37,14 @@
 #define MAX_ITER 20
 #define TOL 1e-14
 
+namespace { // anonymous namespace
 struct MDIST {
 	int nb;
 	double es;
 	double E;
 	double b[1];
 };
+} // anonymous namespace
 	void *
 proj_mdist_ini(double es) {
 	double numf, numfi, twon1, denf, denfi, ens, T, twon;
diff --git a/src/proj_rouss.cpp b/src/proj_rouss.cpp
index f39e0a15..f4fa084f 100644
--- a/src/proj_rouss.cpp
+++ b/src/proj_rouss.cpp
@@ -31,6 +31,7 @@
 #include "proj.h"
 #include "projects.h"
 
+namespace { // anonymous namespace
 struct pj_opaque {
     double s0;
     double A1, A2, A3, A4, A5, A6;
@@ -39,6 +40,7 @@ struct pj_opaque {
     double D1, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11;
     void *en;
 };
+} // anonymous namespace
 PROJ_HEAD(rouss, "Roussilhe Stereographic") "\n\tAzi, Ell";
 
 
diff --git a/src/projinfo.cpp b/src/projinfo.cpp
index 89b42e12..d604365a 100644
--- a/src/projinfo.cpp
+++ b/src/projinfo.cpp
@@ -56,6 +56,7 @@ using namespace NS_PROJ::internal;
 
 // ---------------------------------------------------------------------------
 
+namespace { // anonymous namespace
 struct OutputOptions {
     bool quiet = false;
     bool PROJ5 = false;
@@ -69,6 +70,7 @@ struct OutputOptions {
     bool c_ify = false;
     bool singleLine = false;
 };
+} // anonymous namespace
 
 // ---------------------------------------------------------------------------